This was a project done for a Solid Mechanics class. ANSYS was utilized to design a bracket that could withstand a linearly applied pressure of 2000 psi in the cutaway located on the top right edge. The shape and overall design of the bracket had to meet certain criteria.

1. University of New Haven
Department of Mechanical Engineering
ME 307 Solid Mechanics
Fall semester 2001
Design Project
Done by:
Paul Gibson
Fahad Khan
Instructor: Dr. Stanley

2. Table of Contents
I. Abstract 3
II. Introduction 4
III. Design approach 5
IV. Design Prototype 6
V. Design Prototype Specifications 10
VI. Failed Design Prototype 11
VII. Conclusion 13
VIII. Appendix of ANSYS Plots
i. Line Plot (with dimensions) 14
ii. Area Plot 15
iii. Elements Plot 16
iv. Von Mises Stress 17
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3. Abstract
The purpose of this project was to design a bracket that could withstand a 2000 psi
linearly applied pressure located in a circular cutaway. Only two dimensions were to remain
constant, the radius of the cutaway and the distance the center of that cutaway was from the left
side of the bracket. The final dimensions of the bracket are provided on the line plot in the
appendix. The final area of the bracket was 14.636 with a maximum Von Mises stress of 22112
psi. The file for the project itself is located on the M drive under the name project2. Further
results and details are provided later in this report.
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4. Introduction
In this project a bracket has to be designed using the program ANSYS. The bracket has
the following criteria:
• Made of steel with modules of elasticity of E=30x106
psi.
• Poisson’s ratio, ν , of 0.3.
• Yield stress of 40,000 psi
• Has to be designed to carry a pressure that carries linearly from 0 to 2000 psi on a
180° circular cut out.
• Max Von Misses stress mσ ≤ 60% yield stress. That number is found to be 24000
psi.
The bracket dimensions are given to be:
Height H ≤ 8”
Width W1 = 8 “
Radius R = 1.0”
The minimum width for any section is ≥ 0.25”. Also, cross sectional area should be as
small as possible. Figure 1 depicts the preliminary design requirements. The physical shape of
the bracket is in no means restricted to this exact shape. A design is valid so long as dimension
requirements are met and the mσ ≤ 24000 psi.
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5. Figure 1
Design Approach
As a start, the shape of the bracket shown on the handout was manipulated in nearly
every conceivable manner to achieve the smallest possible surface area. It was soon discovered
that the model shape was not the best one to use if surface area is to be kept at a minimum.
Many failed modifications to the existing shape resulted in a search for a better shape to start
with. Plant hangers are surprisingly sturdy despite their physical appearance, and perhaps, with
a few design alterations, a similar shape could be used for this design. The design criterion calls
for the bracket to be built into a solid surface from the left side, and for a linearly dependent
pressure to be applied to the cutaway on the right side. Although surface area was to be at a
minimum, manufacturing time must also be considered. If the design has multiple holes or
cuttings that need to be made, this can make the design impractical. This need only be a
concern if the bracket is being manufactured by hand. If the bracket is being made form a pre-
made die , then complicated hole cut outs are not a problem. However, since it not specifically
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6. stated in the handout how this bracket is being manufactured, one must take that into account as
a variable. To summarize the basic design approach:
• Basic design and shape was determined.
• Alterations were made on the design to minimize area.
• A check was made to verify that design did not exceed the maximum mσ of
24000 psi.
Design Prototype
Figure 2 shows a line plot of the final design of the bracket. Figure 3 shows the area plot
of the bracket. These screens were captured directly from ANSYS.
Figure 2
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7. It was quickly discovered that stress tends to be high in areas where a sharp or defined
corner was. Nearly every corner in this design was filleted to reduce that tendency for stress
accumulation in those areas.
Figure 4 is an element plot. A mesh size of .05 was used for all final meshes. It was also
found that as mesh size got smaller, the stress got more accurate. Some designs passed the
Von Mises test with a mesh size of .25, but failed when a smaller mesh was used. Figure 5 is a
nodal plot.
Of course, this design would amount to nothing if it failed the Von Mises stress test.
Figure 6 is a Von Mises plot of the deformed shape after loading. It is shown with raster graphics
and 144 contours. Note that the maximum value reached by the mσ is 22112 psi. This is 8.54%
lower than the maximum allowed value of 24000 psi. With the SMX value of 22112 and the
SMXB value of 24108, an error of 9.03% is obtained. Figure 7 is an element solution of the
deformed shape. Slightly different values of stress are obtained. Approximate dimensions of the
bracket are provided on the line plot located in the appendix of this report.
Figure 3
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8. Figure 4
Figure 5
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9. Figure 6
Figure 7
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10. Design Prototype Specifications
What follows below in this section are the geometric properties of the prototype. The final
area was found to be 14.636 sq. inches. The original unaltered design had an area of 28.429.
The final design for the bracket cut area down by 48.52%, nearly half the original.
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PRINT GEOMETRY ITEMS ASSOCIATED WITH THE CURRENTLY SELECTED AREAS
*** NOTE *** CP= 256.379 TIME= 18:04:40
Density not associated with all selected areas. Geometry items are
based on a unit density.
TOTAL NUMBER OF AREAS SELECTED = 1 (OUT OF 1 DEFINED)
TOTAL SURFACE AREA OF ALL SELECTED AREAS = 14.636
TOTAL VOLUME OF ALL SELECTED AREAS = 14.636
CENTROID: XC= 4.4570 YC= 5.4648 ZC= 0.0000
*** MOMENTS OF INERTIA ***
(BASED ON A UNIT DENSITY AND A UNIT THICKNESS)
ABOUT ORIGIN ABOUT CENTROID PRINCIPAL
IXX = 514.87 77.790 49.805
IYY = 375.67 84.933 112.92
IZZ = 890.53 162.72 162.72
IXY = -387.83 -31.354
IYZ = 0.0000 0.0000
IZX = 0.0000 0.0000
PRINCIPAL ORIENTATION VECTORS (X,Y,Z):
0.746 0.666 0.000 -0.666 0.746 0.000 0.000 0.000 1.000
(THXY= 41.751 THYZ= 0.000 THZX= 0.000)

11. Failed Design Prototype
The final design bracket was not the first design that was considered. A similarly shaped
rectangular bracket resembling a magnet was also considered. However, the design was not
efficient. It had a large area and also always had high levels of stress. It was soon learned that
having a bracket made of two parallel sections was poor at minimizing stress. This is why the
final design has one section at an angle to the other. Even though this design failed the Von
Mises stress test, it was also rejected for its large area an general crudeness. Its inclusion in this
report is strictly for comparison purposes. Figure 8 shows the element plot of this design while
Figure 9 is an ordinary line plot. . Figures 10 and 11 are raster and vector plots, respectively, of
the Von Mises stress.
Figure 8
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12. Figure 9
Figure 10
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13. Figure 11
Conclusion
The final design prototype in this report in by no means the absolute best design
possible, nor is it the only one. There are an infinite number of other possibilities. Perhaps
making both sections at angles to each other (rather than have one at an angle and the other
straight) would have lowered the maximum stress slightly, thus allowing for more area to be
subtracted. Whatever the case, it was definitely essential to round all essential corners. The only
areas that had very high stress levels were usually located at sharp, non-rounded corners. By
rounding corners, stress concentrations are less likely to occur. Also, drilled holes were kept to a
minimum in case this bracket is to be manufactured by hand. In conclusion, this design passed
all design requirements established for the project.
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