Difference between revisions of "Boom Construction Competition"

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<h2>OBJECTIVES</h2>
+
=Objective=
  
<p>The experimental objective of this lab is to design and construct a boom, following
+
The experimental objective of this lab is to design and construct a boom following the specifications provided. The boom will be entered in a competition against other booms in the section. The competition will be judged by a ratio that uses boom weight and length, weight held, and anchor time. The highest ratio wins.
the specifications provided. Your boom will be entered in a competition against
 
the other students' booms in your section. You will learn how booms are used and what
 
factors engineers consider when designing them.</p>
 
  
<h2>OVERVIEW</h2>
+
=Overview=
  
<p>A <b><i>boom</i></b> is
+
A <b>boom</b> is used to lift and move heavy objects, often objects that are much heavier than the boom itself. Distributing the weight of the object, or the load, being lifted over the length of the boom is the main problem in boom design. The design must consider the maximum load the boom will be required to lift, how high the load will be lifted, and whether the boom will be moved or remain stationary while loaded.
used to help lift and move heavy objects; objects much heavier than the boom
 
itself. Distributing the weight of the object (the load) being lifted over the
 
length of the boom is the main problem in boom design. The engineer must
 
consider the maximum load the boom will be required to lift, how high the load
 
will need to be lifted, and whether the boom will be moved around while loaded or
 
not.</p>
 
  
<p>Examples of booms that you may not have thought of are certain types of bridges.
+
== Examples of Booms ==
A cantilever bridge is actually two booms extending from a common base. One type of
 
cantilever bridge is a cable-stayed bridge, with a concept of one shown in Figure 1.</p>
 
  
[[Image:Lab_boom_13.png|frame|center|Figure 1: A cable-stayed (cantilever) bridge]]
+
Certain types of bridges use booms. A cantilever bridge uses two booms extending from a common base. One type of cantilever bridge is a cable-stayed bridge (Figure 1).
  
<p>The Queensboro Bridge is an example of a double cantilever bridge, and is shown in
+
[[Image:Lab_boom_13.png|650px|thumb|center|Figure 1: A Cable-Stayed (Cantilever) Bridge]]
Figure 2. If youlook carefully at the figure, you'll see two bases, and the two
 
booms extending from each base, with the cantilevers placed end to end.</p>
 
  
[[Image:lab_boom_10.jpg|frame|center|Figure 2: Queensboro Bridge (double cantilever)]]
+
The Ed Koch Queensboro Bridge is a double cantilever bridge (Figure 2). It has two bases with two booms extending from each base and the cantilevers placed end to end.
  
<p>The Grand Bridge over Newtown Creek is an example of a swing bridge, also known as
+
[[Image:lab_boom_10.jpg|frame|center|Figure 2: Ed Koch Queensboro Bridge (Double Cantilever)]]
a rotating bridge, and is shown in Figure 3. In this case, the bridge is two booms
 
mounted on a base that rotates.</p>
 
  
[[Image:lab_boom_11.jpg|frame|center|Figure 3: Grand Bridge (swing bridge)]]
+
The Grand Bridge over Newtown Creek is a swing bridge, also known as a rotating bridge (Figure 3). This bridge has two booms mounted on a base that rotates.
  
<p>Finally, Figure 4 shows a bascule bridge, more commonly known as a drawbridge, where
+
[[Image:lab_boom_11.jpg|650px|thumb|center|Figure 3: Grand Bridge (Swing Bridge)]]
it's clear that the bridge is a big very flat boom.</p>
 
  
[[Image:lab_boom_12.jpg|frame|center|Figure 4: A typical buscule bridge]]
+
Figure 4 shows a bascule bridge, more commonly known as a drawbridge, where it is clear that the bridge uses a big, very flat boom.
  
<p>Note that not all bridges are booms. For example, suspension bridges, where the deck
+
[[Image:lab_boom_12.jpg|650px|thumb|center|Figure 4: Bascule Bridge]]
is supported by steel cables, are not booms. Examples of suspension bridges are the
 
Brooklyn Bridge, Manhattan Bridge, Verrazano-Narrows Bridge, and George Washington Bridge.</p>
 
  
<p>Cranes are the most common example of booms in action. The crane pictured
+
Not all bridges are booms. Suspension bridges use a deck that is supported by steel cables, not booms. Examples of suspension bridges are the Brooklyn Bridge, Manhattan Bridge, Verrazano-Narrows Bridge, and the George Washington Bridge.
in Figure 5 is a tower crane. These cranes are a
 
fixture on construction sites across the country and around the world. A tower
 
crane can lift a staggering 40,000 pound load of construction material and
 
machinery. It is attached to the ground by anchor bolts driven through a
 
400,000-pound concrete pad poured a few weeks before the crane is erected.<sup>1</sup></p>
 
  
[[Image:lab_boom_6.jpg|frame|center|Figure 5: A tower crane (from www.howstuffworks.com)]]
+
Cranes are the most common example of booms. The crane pictured in Figure 5 is a tower crane. These cranes are a fixture on construction sites around the world. A tower crane can lift a 40,000-pound load. It is attached to the ground by anchor bolts driven through a 400,000-pound concrete pad poured a few weeks before the crane is erected (Howstuffworks.com, 2003).
  
<p><b>FYI:</b>
+
[[Image:Tower Crane.jpg|650px|thumb|center|Figure 5: A Tower Crane (Jennings, 2015)]]
<ul>
+
 
<li>A Dead Load is a stationary load</li>
+
== Stress and Strain ==
<li>A Live Load is a moving or mobile load</li>
 
<li>A Cyclic Load is a load that changes periodically</li>
 
</ul>
 
  
When you work on the design for your boom, you must take into account the properties
+
The design of a boom must consider the properties of the materials used to build the boom. The mechanical properties and deformation of solids are explained by stress and strain. When an external force is applied to a material, it changes shape (e.g. changes length and cross-section perpendicular to the length). Understanding how deformation will affect materials is a critical consideration in boom design.
of the materials you will use. To discuss the mechanical properties and
 
deformation of solids, we must first understand stress and strain. When an
 
external force is applied to a piece of material, it changes shape (e.g.,
 
changes length and cross section perpendicular to the length). Understanding how such deformations will
 
affect materials is critical information for an engineer.</p>
 
  
<p>There are three basic types of stresses; tensile (pulling or stretching), compressive
+
According to Serway and Beichner in “Physics for Scientists and Engineers,” <b>stress</b> is the external force acting on an object per unit cross sectional area. <b>Strain</b> is the measure of deformation resulting from an applied stress (Figure 6).
(squeezing or squashing) and shear (bending or cleaving).  If a rod of material is put under tensile
 
stress, its length increases slightly in the direction of the applied force and
 
its cross-section perpendicular to the force decreases.  If the rod is placed under compressive
 
stress, its length in the direction of the force will decrease and its cross-section
 
perpendicular to the force will increase.  
 
If the rod is place under shear stress it will bend in the direction of
 
the applied force and its length and cross-section will be distorted, see
 
Figure 6.</p>
 
  
[[Image:Lab_boom_7.gif|frame|center|Figure 6: Rods of Material being stressed.]]
+
[[Image:lab_boom_1.jpg|frame|center|Figure 6: Material Under Tension]]
  
<p>According to Serway and Beichner in <i>Physics for Scientists and Engineers,<sup>2</sup></i>
+
The expression (1) for tensile stress shows the relationship between an applied force and the cross-sectional area.
<b><i>stress </i></b>is
 
the external force acting on an object per unit cross sectional area. <b><i>Strain </i></b>is the measure of
 
deformation resulting from an applied <b><i>stress</i></b>.
 
</p>
 
  
[[Image:lab_boom_1.jpg|frame|center|Figure 7: A piece of material under tension.]]
+
<center><math>\sigma = \frac{F}{A}\,</math></center>
 +
<p style="text-align:right">(1)</p>
  
<p>The expression for tensile stress is:</p>
+
In (1), &sigma; is the stress, F is the applied force, and A is the cross-sectional area of the object perpendicular to the force. The resulting strain (2) is calculated by dividing the change in length of the object by the original length.
  
<math>\sigma = \frac{F}{A}\,</math>
+
<center><math>\varepsilon = \frac{\Delta L}{L_{\text{0}}}\,</math></center>
 +
<p style="text-align:right">(2)</p>
  
<p>where <i>s</i> is the stress, <i>F</i><i> </i>is the applied force and <i>A </i>is
+
In (2), &Delta;L is the change in length and L<sub>0</sub> is the object's original length.
the cross-sectional area of the object perpendicular to the force. The expression for the
 
resulting strain <i>e</i> is:</p>
 
  
<math>\varepsilon = \frac{\Delta L}{L_{\text{0}}}\,</math>
+
There are three basic types of stresses; tensile (pulling or stretching), compressive (squeezing or squashing), and shear (bending or cleaving). If a rod of material is put under <b>tensile stress</b>, its length increases slightly in the direction of the applied force and its cross-section perpendicular to the force decreases. If the rod is placed under <b>compressive stress</b>, its length in the direction of the force will decrease and its cross-section perpendicular to the force will increase. If the rod is place under <b>shear stress</b>, it will bend in the direction of the applied force and its length and cross-section will be distorted (Figure 7).
  
<p>where <math>\Delta L\,</math>is the change in length and <i>L</i><i><sub>0</sub></i><i> </i>is
+
[[Image:Lab_boom_7.gif|frame|center|Figure 7: Rods of Material Under Stress]]
the object's original length.</p>
 
  
<p>Strain is proportional to stress for small values of strain, and the proportionality
+
Strain is proportional to stress for small values of strain. The proportionality constant depends on the material being deformed and on the type of deformation. The proportionality constant is called the <b>elastic modulus</b>, or Young’s modulus. The moduli for different materials vary considerably and the various moduli for a particular material may also vary significantly. Concrete, for example, is very strong in compression, but less so in tension, and wood breaks quite easily when bent because its natural grain is anisotropic (properties depend on the direction of the material).
constant depends on the material being deformed and on the type of
 
deformation. The proportionality
 
constant is called an elastic modulus.  
 
The moduli for different materials vary
 
considerably and the various moduli for a particular
 
material may also vary significantly, e.g., concrete is very strong in
 
compression but less so in tension; wood breaks quite easily when bent, and
 
because of its natural grain is anisotropic (properties depend on direction in
 
the material).</p>
 
  
[[Image:lab_boom_2.jpg|frame|center|Figure 8: Stress-Strain relation for a piece of material under tension]]
+
== Stress-Strain Curve ==
  
<p>Figure 8 shows the effects of tensile stress on a typical rod of material. In the
+
A <b>stress-strain curve</b> graphically shows the relationship between the stress and strain of a material under load (Figure 8). In the <b>elastic region</b>, the material will regain its original shape once the stress or load is removed. In the <b>plastic region</b>, the material loses its elasticity and is permanently deformed.
elastic region, the material will regain its original shape once the stress (or
 
load) is removed. In the plastic region,
 
the material loses its elasticity and is permanently deformed.</p>
 
  
<p>The <b><i>elastic limit</i></b> for
+
[[Image:lab_boom_2.jpg|frame|center|Figure 8: Stress-Strain Curve of a Material Under Tension]]
a material is the maximum strain it can sustain before it becomes permanently
 
deformed (i.e. if you decrease the stress, the object no longer relaxes back to
 
its original size and shape).  If you
 
increase the stress past the elastic limit, the material will plastically
 
deform and for sufficiently large stress ultimately fail. The ultimate tensile strength<b><i> </i></b>is
 
the maximum amount of stress a material can undergo. The fracture stress<b><i> </i></b>is
 
the point at which the material breaks under tension.  Fracture
 
stress<b><i> </i></b>is lower than the ultimate tensile strength<b><i> </i></b>because
 
as strain increases, the material becomes thinner and thinner.  As this necking down process continues, the
 
amount of load that can be supported decreases and the material breaks.</p>
 
  
<p>In addition to these intrinsic materials factors, an
+
The <b>elastic limit</b> for a material is the maximum strain it can sustain before it becomes permanently deformed (i.e. if the stress is decreased, the object no longer returns to its original size and shape). If the stress is greater than the elastic limit, the material will plastically deform and for sufficiently large stress ultimately fail. The <b>ultimate tensile strength</b> is the maximum stress a material can undergo. The <b>fracture stress</b> is the point at which the material breaks under tension. Fracture stress is lower than the ultimate tensile strength because as strain increases, the material becomes thinner and thinner. As this necking down process continues, the load that can be supported decreases and the material breaks.
engineer must consider the behavior of materials as they age and are used in
 
service. These factors do not relate
 
directly to the design of your "one-time-use" boom, but they need to be taken
 
into consideration when deciding what material to use for an actual
 
design. The loss of desirable properties through use, called fatigue, is
 
often an important issue. Non-static
 
loads, repeated loading and unloading, or loads that include vibrations,
 
oscillations etc., may lead to failure in service.  Special care must be taken with live loads
 
and situations where small motions may be magnified by design features.</p>
 
  
<p>The first aging factor is chemical degradation and, in particular, <b><i>corrosion</i></b>.  Light and  
+
In addition to these intrinsic materials factors, the behavior of materials as they age and are used in service must be considered in boom design. These factors do not relate directly to the boom design in this lab, but they must be considered when deciding what material to use for an actual design. The loss of desirable properties through use, called <b>fatigue</b>, is important. Non-static loads, repeated loading and unloading, or loads that include vibrations or oscillations may lead to failure in service. Special care must be taken with live loads and situations where small motions may be magnified by design features.
 +
<!--<p>The first aging factor is chemical degradation and, in particular, <b><i>corrosion</i></b>.  Light and  
  
 
chemicals present in the
 
chemicals present in the
Line 150: Line 76:
 
rust results when iron or simple steel is exposed to water, or just even humid
 
rust results when iron or simple steel is exposed to water, or just even humid
 
air.  Rust is particularly damaging
 
air.  Rust is particularly damaging
because it flakes off, thinning and weakening the underlying material.  Careful choice of material will minimize the effects of chemical degradation.  However
+
because it flakes off, thinning and weakening the underlying material.  Careful choice of material will minimize the effects of chemical degradation.  However,
cost is often limiting factor and cheap counter measures like paint and other
+
the cost is often limiting factor and cheap countermeasures like paint and other
 
coatings are often employed.</p>
 
coatings are often employed.</p>
  
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process.  Care in the design process can
 
process.  Care in the design process can
 
help minimize the effect of erosion.  
 
help minimize the effect of erosion.  
Again cost is often the limiting factor and coatings are often employed
+
Again the cost is often the limiting factor and coatings are often employed
 
to protect an object.</p>
 
to protect an object.</p>
  
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cycling</i></b>.  Materials in an object
 
cycling</i></b>.  Materials in an object
 
will routinely warm up and cool down while in use (especially device that
 
will routinely warm up and cool down while in use (especially device that
generate heat internally), over the course of a normal day, or even over a
+
generates heat internally), over the course of a normal day, or even over a
 
year.  This thermal cycling is
 
year.  This thermal cycling is
 
accompanied by physical expansion and contraction of the object.  Different materials expand and contract by
 
accompanied by physical expansion and contraction of the object.  Different materials expand and contract by
 
different amounts and this can lead to internal stress and strains, and
 
different amounts and this can lead to internal stress and strains, and
 
ultimately failure.  Careful choice and
 
ultimately failure.  Careful choice and
matching of materials can minimize the effects of thermal cycling, but cost may
+
matching of materials can minimize the effects of thermal cycling, but the cost may
 
limit the choices.  Accumulations of
 
limit the choices.  Accumulations of
 
water, which can freeze and thaw, can be very damaging and coatings are often
 
water, which can freeze and thaw, can be very damaging and coatings are often
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treatment (annealing) and in general, material properties can be improved
 
treatment (annealing) and in general, material properties can be improved
 
significantly through heat treatment and mechanical working.  For example, the familiar Pyrex<sup>TM</sup>
 
significantly through heat treatment and mechanical working.  For example, the familiar Pyrex<sup>TM</sup>
glass is specially treated to avoid thermal shock.</p>
+
glass is specially treated to avoid thermal shock.</p>-->
  
<p>There are many factors to consider in any design project. When designing and
+
There are many factors to consider in any design project. When designing and constructing the boom for this competition, remember to consider the materials being used and what might cause those materials to fail under a load.
constructing your boom for this competition, remember to consider the materials
 
you are using and what might cause those materials to fail under a load.</p>
 
  
<h2>COMPETITION RULES</h2>
+
=Competition Rules=
  
<p>The competition rules must be followed at all times during the competition.
+
The competition rules must be followed at all times during the competition.
Violation of any of these rules will result in the disqualification of your
+
Violation of any of these rules will result in the disqualification of the
team.</p>
+
design.
  
 
<ul>
 
<ul>
<li>Your boom must extend at least 1.5 meters horizontally from the front edge of
+
<li>The boom is to be secured (i.e. anchored) to the white plastic anchorage provided at the front of the lab
the anchorage.</li>
+
<li>The boom must extend at least 1.5 meters horizontally from the front edge of
 +
the anchorage</li>
 +
<li>The boom must be anchored in two minutes or less</li>
 +
<li>The boom may not touch anything but the anchorage</li>
 +
<li>The <b>basic weight ratio</b> (3) for the competition uses the weight supported divided by the boom weight</li><br>
  
<li>You have 2 minutes to anchor your boom.</li>
+
<center><math>Weight\ Ratio = \frac{Weight\ Supported}{Boom\ Weight}\,</math></center>
 +
<p style="text-align:right">(3)</p>
  
<li>Your boom may not touch anything but the anchorage.</li>
+
<li>The winning design will be determined by the <b>weighted design ratio</b> (4), which uses the weight ratio, anchor time, and boom length</li>
 
 
<li>The
 
basic weight ratio for the competition is:</li>
 
 
 
<math>Weight\ Ratio = \frac{Weight\ Supported}{Boom\ Weight}\,</math>
 
 
 
<li>The winning design will be determined based on the following weighted design ratio:</li>
 
 
</ul>
 
</ul>
  
<math>Design\ Ratio = \frac{Weight\ Supported}{Boom\ Weight} \times \frac{60\left[\text{s}\right]}{Anchor\ Time\left[\text{s}\right]+30\left[\text{s}\right]} \times \frac{Boom\ Length\left[\text{m}\right]}{1.5\left[\text{m}\right]}\,</math>
+
<center><math>Design\ Ratio = \frac{Weight\ Supported}{Boom\ Weight} \times \frac{60\left[\text{s}\right]}{Anchor\ Time\left[\text{s}\right]+30\left[\text{s}\right]} \times \frac{Boom\ Length\left[\text{m}\right]}{1.5\left[\text{m}\right]}\,</math></center>
 +
<p style="text-align:right">(4)</p>
  
<h2>Design Considerations</h2>
+
=Design Considerations=
* Which aspects of the competition formula are most advantageous?
+
* Which aspects of the competition ratio are most advantageous?
 
* How can the boom be built and/or reinforced to prevent as much deflection as possible?
 
* How can the boom be built and/or reinforced to prevent as much deflection as possible?
  
<p>Note: You and your partner are to design a boom.
+
=Materials and Equipment=
The boom is to be secured (i.e., anchored) to the white plastic
 
anchorage provided at the front of the lab.
 
The boom must extend at least 1.5 m from the front edge of the anchorage
 
and deflect as little as possible when loaded.</p>
 
 
 
<h2>MATERIALS AND EQUIPMENT</h2>
 
 
<ul>
 
<ul>
<li>2 Thick Dowels (1.1cm x 122cm)</li>
+
<li>Two thick dowels (1.1 cm &times; 122 cm)</li>
<li>2 Thin Dowels (0.8cm x 122cm)</li>
+
<li>Two thin dowels (0.8 cm &times; 122 cm)</li>
<li>6 Bamboo Skewers (30.5cm)</li>
+
<li>Six bamboo skewers (30.5 cm)</li>
<li>3D Printed Dowel Connectors</li>
+
<li>3D printed dowel connectors</li>
<li>Cellophane Tape</li>
+
<li>Cellophane tape</li>
<li>Kevlar String</li>
+
<li>Kevlar string</li>
 
</ul>
 
</ul>
  
<br /><font color="red"><b>'''NOTE: A saw is available to cut the dowels. Ask your TA for assistance, as students are not allowed to use the saw.'''</b></font>
+
<font color="red"><b>'''Note: A saw is available to cut the dowels. Ask a TA for assistance, as only TAs may use the saw.'''</b></font>
 
 
 
 
 
 
[[Image:lab_boom_15.jpg|thumb|400px|frame|center|Figure 9: 3D Printed Dowel Connectors]]
 
  
<h2>PROCEDURE</h2>
+
=Procedure=
  
 
<h3>Boom Design and Construction</h3>
 
<h3>Boom Design and Construction</h3>
  
<ol>
+
# Assess the materials and consider the design options, keeping in mind the competition specifications. Preliminary sketches must be completed during this process</li>
<li>Assess your materials and consider your design options, keeping in mind the
+
# Sketch the basic design in pencil using the lab notes paper provided by a TA or on the EG1003 website. Label the design clearly and have a TA sign and date it
competition specifications. Make sure you make preliminary
+
# Construct the boom based on the completed sketch and the available materials. A TA will provide the materials allowed for the design. If the design is modified during the construction phase, make sure to note the changes and describe the reasons for them
sketches during this process.</li>
+
# A TA will weigh the boom and record the weight in the competition spreadsheet for the section
 
 
<li>Now sketch your actual basic design in pencil using the graph paper sample
 
provided on the EG website. Label your design clearly and have your TA <b>sign and date </b>it.</li>
 
 
 
<li>Construct your boom based on the sketch you just completed and the available
 
materials. Your TA will provide the materials allowed for your design. If you
 
decide to modify your design during the construction phase of your boom, make
 
sure to note the changes and describe your reasons for them.</li>
 
 
 
<li>Your TA will weigh your boom and record the weight in the competition
 
spreadsheet for your section.</li>
 
</ol>
 
  
 
<h3>Competition</h3>
 
<h3>Competition</h3>
  
<p><b>Note: </b><i>Attaching your boom to the
+
<p><b>Note: </b>Attaching the boom to the anchorage is a critical phase of the competition. Anchoring will be timed. Making sure there is a plan to anchor the boom quickly will improve its standing in the competition. Practice anchoring before the trial begins. The boom will be disqualified if anchoring the boom takes more than two minutes.
anchorage is a critical phase of the competition. You will be timed. Making
 
sure you have a plan before you start will help you anchor the boom quickly and
 
improve your standing in the competition. You may want to practice before your
 
trial begins. Remember you will be disqualified if anchoring your boom takes
 
more than two minutes.</i></p>
 
  
<ol>
+
# When the TA says "go," attach the boom to the anchorage and shout "done" when the boom is anchored. The TA will only stop the timer once there are no more hands touching the boom. The TA will give the anchoring time. This value will be used to compute the boom's design ratio
<li>When the TA says "go," attach your boom to the anchorage and shout "done" when
+
# A TA will measure the boom and record the length in the competition spreadsheet for the section
your team is finished. The TA will give you your anchoring time. You will use this
+
# A TA will attach a basket to the end of the boom and add weights until the boom deflects (bends) 0.2 m vertically. The load supported will be weighed on the lab scale and recorded in the competition spreadsheet for the section (Figure 10)
number to compute your boom's design ratio. </li>
 
 
 
<li>Your TA will measure your boom and record the length in the
 
competition spreadsheet for your section.</li>
 
 
 
<li>Your TA will attach a basket to the end of your boom and add weights until the
 
boom deflects (bends) 0.2 m. The load supported will be weighed on the lab
 
scale and the weight recorded in the competition spreadsheet for your section.
 
See Figure 9.</li>
 
</ol>
 
 
[[Image:lab_boom_5.jpg|frame|center|Figure 10: Sample Competition Spreadsheet]]
 
[[Image:lab_boom_5.jpg|frame|center|Figure 10: Sample Competition Spreadsheet]]
  
<p>Your TA has prepared an Excel file with your section's results. Go to the [http://eg.poly.edu/documents.php Lab Documents] section of the EG Website. This chart must be included in your
+
<p>A TA has prepared an Excel file with the section's results. It can be accessed in the [http://eg.poly.edu/documents.php Lab Documents] section of the EG1003 website. This chart must be included in the PowerPoint presentation and in the Data/Observations section of the lab report. The lab work is now complete. Please clean up the workstation. Return all unused materials to a TA. Refer to the Assignment section for the instructions to prepare the lab report.
PowerPoint presentation and in the data section of your lab report. Your lab work is now complete. Please clean  
 
 
 
up your workstation. Return all unused materials to your TA. Refer to section <b><i>3 Your Assignment</i></b>
 
for the instructions you need to prepare your lab report.</p>
 
 
 
<h2>ASSIGNMENT</h2>
 
  
<h3>Team Lab Report</h3>
+
=Assignment=
<!--
 
* For EG1003: This is a REQUIRED TEAM Lab Report
 
*: <b>Note:</b> You will be writing a team lab report rather than an individual one. See the [[Team Authoring Strategies]] page in the <i>Technical Communication</i> of this online manual for guidance of how to do this.
 
* For EGED I: This is a BONUS INDIVIDUAL Lab Report
 
-->
 
  
<b>Note:</b> Since this lab is a competition, you will be writing a team lab report rather than an
+
{{Labs:Lab Report}}
individual one. See the [[Team Authoring Strategies]] page in the <i>Technical Communication</i> of
 
this online manual for guidance of how to do this.
 
 
 
<p>Follow the lab report guidelines laid out in the page called [[Specifications for Writing Your Lab Reports]]
 
in the <i>Technical Communication</i> section of this manual.
 
As you write, the following discussion points should be addressed in the appropriate
 
section of your lab report:</p>
 
  
 
<ul>
 
<ul>
<li>Describe the rules of the competition in your introduction. What consequences did the rules have for
+
<li> Describe the rules of the competition in the Introduction. What consequences did the rules have for any design decisions? Use the appropriate equations in the answer.</li>
your design decisions? Use the appropriate equations in your answer.</li>
+
<li>What factors were considered in designing the boom? Was any of the
 
+
background information used?</li>
<li>What factors did you consider in designing your boom? Did you use any of the
+
<li>What was the basic weight ratio and weighted design ratio for the design?</li>
background information?</li>
+
<li>Describe how the components chosen functioned in the design, and describe its height/length/shape</li>
 
+
<li>Describe the advantages and disadvantages of the boom design</li>
<li>What was the weight ratio and design ratio for your design?</li>
+
<li>Discuss design improvements. How can the design be optimized (i.e. improve the ratio) based on experience?</li>
 
 
<li>What do you think would be the maximum design ratio for this project? Compare
 
your results with this ideal ratio.</li>
 
 
 
<li>What important design characteristics should a winning boom include to achieve
 
the highest possible weighted ratio?</li>
 
 
 
<li>Describe how the components you have chosen function in your design, and describe its overall height/length/shape/etc.</li>
 
 
 
<li>Discuss design improvements. How would you optimize the design (i.e. improve the ratio)
 
based on experience?</li>
 
 
 
 
<li>Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?
 
<li>Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?
 
+
<li>Include the spreadsheet with every boom's results. Describe the results and talk about other designs in the class
<li>Include spreadsheet with every team's results. Describe the results and talk about other designs in the class.
 
  
 
</ul>
 
</ul>
  
{{Lab notes}}
+
{{Labs:Lab Notes}}
  
 
<h3>Team PowerPoint Presentation</h3>
 
<h3>Team PowerPoint Presentation</h3>
  
<p>Follow the presentation guidelines laid out in the page called [[EG1003 Lab Presentation Format]]
+
{{Labs:Team Presentation}}
in the <i>Introduction to Technical Presentations</i> section of this manual.
 
When you are preparing your presentation, consider the following points:</p>
 
  
 
<ul>
 
<ul>
<li>How would you improve your boom design?</li>
+
<li>How can the boom design be improved?</li>
 
<li>Other than the examples given in this lab, what are other examples of booms?</li>
 
<li>Other than the examples given in this lab, what are other examples of booms?</li>
 
<li>Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?
 
<li>Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?
 
</ul>
 
</ul>
  
<h2>Footnotes</h2>
+
= References =
 +
 
 +
<i>How Stuff Works</i> website. 2003. SHW Media Network. Retrieved July 28, 2003.
 +
http://science.howstuffworks.com/tower-crane3.htm
  
<p><sup>1</sup> <i>How Stuff Works </i>website. 2003. SHW Media Network. Retrieved July 28<sup>th</sup>, 2003.
+
Jennings, James. 2015. “Up, UP in a Crane: What Life is Like as a Tower Crane Operator.” Philadelphia. Accessed 14 January 2020 from www.phillymag.com
<i>http://science.howstuffworks.com/tower-crane3.htm</i></p>
 
  
<p><sup>2</sup> Serway, R., Beichner, R., <i>Physics for Scientists and Engineers with Modern Physics, 5</i><i><sup>th</sup></i>
+
Serway, R., Beichner, R., <i>Physics for Scientists and Engineers with Modern Physics, 5</i><i><sup>th</sup></i> Edition. Fort Worth, TX: Saunders College Publishing, 2000
<i>Edition</i>. Fort Worth, TX: Saunders College Publishing, 2000</p>
 
  
[[Main_Page | Return to Table of Contents]]
+
{{Laboratory Experiments}}

Latest revision as of 16:58, 25 March 2020

Objective

The experimental objective of this lab is to design and construct a boom following the specifications provided. The boom will be entered in a competition against other booms in the section. The competition will be judged by a ratio that uses boom weight and length, weight held, and anchor time. The highest ratio wins.

Overview

A boom is used to lift and move heavy objects, often objects that are much heavier than the boom itself. Distributing the weight of the object, or the load, being lifted over the length of the boom is the main problem in boom design. The design must consider the maximum load the boom will be required to lift, how high the load will be lifted, and whether the boom will be moved or remain stationary while loaded.

Examples of Booms

Certain types of bridges use booms. A cantilever bridge uses two booms extending from a common base. One type of cantilever bridge is a cable-stayed bridge (Figure 1).

Figure 1: A Cable-Stayed (Cantilever) Bridge

The Ed Koch Queensboro Bridge is a double cantilever bridge (Figure 2). It has two bases with two booms extending from each base and the cantilevers placed end to end.

Figure 2: Ed Koch Queensboro Bridge (Double Cantilever)

The Grand Bridge over Newtown Creek is a swing bridge, also known as a rotating bridge (Figure 3). This bridge has two booms mounted on a base that rotates.

Figure 3: Grand Bridge (Swing Bridge)

Figure 4 shows a bascule bridge, more commonly known as a drawbridge, where it is clear that the bridge uses a big, very flat boom.

Figure 4: Bascule Bridge

Not all bridges are booms. Suspension bridges use a deck that is supported by steel cables, not booms. Examples of suspension bridges are the Brooklyn Bridge, Manhattan Bridge, Verrazano-Narrows Bridge, and the George Washington Bridge.

Cranes are the most common example of booms. The crane pictured in Figure 5 is a tower crane. These cranes are a fixture on construction sites around the world. A tower crane can lift a 40,000-pound load. It is attached to the ground by anchor bolts driven through a 400,000-pound concrete pad poured a few weeks before the crane is erected (Howstuffworks.com, 2003).

Figure 5: A Tower Crane (Jennings, 2015)

Stress and Strain

The design of a boom must consider the properties of the materials used to build the boom. The mechanical properties and deformation of solids are explained by stress and strain. When an external force is applied to a material, it changes shape (e.g. changes length and cross-section perpendicular to the length). Understanding how deformation will affect materials is a critical consideration in boom design.

According to Serway and Beichner in “Physics for Scientists and Engineers,” stress is the external force acting on an object per unit cross sectional area. Strain is the measure of deformation resulting from an applied stress (Figure 6).

Figure 6: Material Under Tension

The expression (1) for tensile stress shows the relationship between an applied force and the cross-sectional area.

(1)

In (1), σ is the stress, F is the applied force, and A is the cross-sectional area of the object perpendicular to the force. The resulting strain (2) is calculated by dividing the change in length of the object by the original length.

(2)

In (2), ΔL is the change in length and L0 is the object's original length.

There are three basic types of stresses; tensile (pulling or stretching), compressive (squeezing or squashing), and shear (bending or cleaving). If a rod of material is put under tensile stress, its length increases slightly in the direction of the applied force and its cross-section perpendicular to the force decreases. If the rod is placed under compressive stress, its length in the direction of the force will decrease and its cross-section perpendicular to the force will increase. If the rod is place under shear stress, it will bend in the direction of the applied force and its length and cross-section will be distorted (Figure 7).

Figure 7: Rods of Material Under Stress

Strain is proportional to stress for small values of strain. The proportionality constant depends on the material being deformed and on the type of deformation. The proportionality constant is called the elastic modulus, or Young’s modulus. The moduli for different materials vary considerably and the various moduli for a particular material may also vary significantly. Concrete, for example, is very strong in compression, but less so in tension, and wood breaks quite easily when bent because its natural grain is anisotropic (properties depend on the direction of the material).

Stress-Strain Curve

A stress-strain curve graphically shows the relationship between the stress and strain of a material under load (Figure 8). In the elastic region, the material will regain its original shape once the stress or load is removed. In the plastic region, the material loses its elasticity and is permanently deformed.

Figure 8: Stress-Strain Curve of a Material Under Tension

The elastic limit for a material is the maximum strain it can sustain before it becomes permanently deformed (i.e. if the stress is decreased, the object no longer returns to its original size and shape). If the stress is greater than the elastic limit, the material will plastically deform and for sufficiently large stress ultimately fail. The ultimate tensile strength is the maximum stress a material can undergo. The fracture stress is the point at which the material breaks under tension. Fracture stress is lower than the ultimate tensile strength because as strain increases, the material becomes thinner and thinner. As this necking down process continues, the load that can be supported decreases and the material breaks.

In addition to these intrinsic materials factors, the behavior of materials as they age and are used in service must be considered in boom design. These factors do not relate directly to the boom design in this lab, but they must be considered when deciding what material to use for an actual design. The loss of desirable properties through use, called fatigue, is important. Non-static loads, repeated loading and unloading, or loads that include vibrations or oscillations may lead to failure in service. Special care must be taken with live loads and situations where small motions may be magnified by design features.

There are many factors to consider in any design project. When designing and constructing the boom for this competition, remember to consider the materials being used and what might cause those materials to fail under a load.

Competition Rules

The competition rules must be followed at all times during the competition. Violation of any of these rules will result in the disqualification of the design.

  • The boom is to be secured (i.e. anchored) to the white plastic anchorage provided at the front of the lab
  • The boom must extend at least 1.5 meters horizontally from the front edge of the anchorage
  • The boom must be anchored in two minutes or less
  • The boom may not touch anything but the anchorage
  • The basic weight ratio (3) for the competition uses the weight supported divided by the boom weight

  • (3)

  • The winning design will be determined by the weighted design ratio (4), which uses the weight ratio, anchor time, and boom length

(4)

Design Considerations

  • Which aspects of the competition ratio are most advantageous?
  • How can the boom be built and/or reinforced to prevent as much deflection as possible?

Materials and Equipment

  • Two thick dowels (1.1 cm × 122 cm)
  • Two thin dowels (0.8 cm × 122 cm)
  • Six bamboo skewers (30.5 cm)
  • 3D printed dowel connectors
  • Cellophane tape
  • Kevlar string

Note: A saw is available to cut the dowels. Ask a TA for assistance, as only TAs may use the saw.

Procedure

Boom Design and Construction

  1. Assess the materials and consider the design options, keeping in mind the competition specifications. Preliminary sketches must be completed during this process
  2. Sketch the basic design in pencil using the lab notes paper provided by a TA or on the EG1003 website. Label the design clearly and have a TA sign and date it
  3. Construct the boom based on the completed sketch and the available materials. A TA will provide the materials allowed for the design. If the design is modified during the construction phase, make sure to note the changes and describe the reasons for them
  4. A TA will weigh the boom and record the weight in the competition spreadsheet for the section

Competition

Note: Attaching the boom to the anchorage is a critical phase of the competition. Anchoring will be timed. Making sure there is a plan to anchor the boom quickly will improve its standing in the competition. Practice anchoring before the trial begins. The boom will be disqualified if anchoring the boom takes more than two minutes.

  1. When the TA says "go," attach the boom to the anchorage and shout "done" when the boom is anchored. The TA will only stop the timer once there are no more hands touching the boom. The TA will give the anchoring time. This value will be used to compute the boom's design ratio
  2. A TA will measure the boom and record the length in the competition spreadsheet for the section
  3. A TA will attach a basket to the end of the boom and add weights until the boom deflects (bends) 0.2 m vertically. The load supported will be weighed on the lab scale and recorded in the competition spreadsheet for the section (Figure 10)
Figure 10: Sample Competition Spreadsheet

A TA has prepared an Excel file with the section's results. It can be accessed in the Lab Documents section of the EG1003 website. This chart must be included in the PowerPoint presentation and in the Data/Observations section of the lab report. The lab work is now complete. Please clean up the workstation. Return all unused materials to a TA. Refer to the Assignment section for the instructions to prepare the lab report.

Assignment

Follow the lab report guidelines laid out in the EG1003 Writing Style Guide in the Technical Writing section of the manual. The following points should be addressed in the appropriate section of the lab report.

  • Describe the rules of the competition in the Introduction. What consequences did the rules have for any design decisions? Use the appropriate equations in the answer.
  • What factors were considered in designing the boom? Was any of the background information used?
  • What was the basic weight ratio and weighted design ratio for the design?
  • Describe how the components chosen functioned in the design, and describe its height/length/shape
  • Describe the advantages and disadvantages of the boom design
  • Discuss design improvements. How can the design be optimized (i.e. improve the ratio) based on experience?
  • Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?
  • Include the spreadsheet with every boom's results. Describe the results and talk about other designs in the class

Remember: Lab notes must be taken. Experimental details are easily forgotten unless written down. EG1003 Lab Notes paper can be downloaded and printed from the EG1003 Website. Use the lab notes to write the Procedure section of the lab report. At the end of each lab, a TA will scan the lab notes and upload them to the Lab Documents section of the EG1003 Website. One point of extra credit is awarded if the lab notes are attached at the end of the lab report. Keeping careful notes is an essential component of all scientific practice.

Team PowerPoint Presentation

Follow the presentation guidelines laid out in the EG1003 Lab Presentation Format in the Technical Presentations section of the manual. When preparing the presentation, consider the following points.

  • How can the boom design be improved?
  • Other than the examples given in this lab, what are other examples of booms?
  • Which elements of the boom (e.g., wooden dowels, 3D printed dowel connectors, Kevlar string, etc.,) were stressed by the load, in what directions, and contributed to the failure?

References

How Stuff Works website. 2003. SHW Media Network. Retrieved July 28, 2003. http://science.howstuffworks.com/tower-crane3.htm

Jennings, James. 2015. “Up, UP in a Crane: What Life is Like as a Tower Crane Operator.” Philadelphia. Accessed 14 January 2020 from www.phillymag.com

Serway, R., Beichner, R., Physics for Scientists and Engineers with Modern Physics, 5th Edition. Fort Worth, TX: Saunders College Publishing, 2000