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Design I

ME 353 - Engineering Design I - this course introduced the design/selection of mechanical components including bolts and nuts, springs, screws, and welded joints. Some topics covered are:

  • Strain energy methods
  • Static material failure criteria
  • Fatigue failure criteria
  • Linear elastic finite element formulations
  • ANSYS general finite element program
  • Selection of screws and bolts - design of bolted connections
  • Design and selection of mechanical springs and their applications

Finite element analysis is a relatively new method to analyze forces and stresses on beams because it was specifically developed to be programmed into a computer. In this class, we analyzed forces on simple cantilever beams, both by calculating all of the information by hand and also using the finite element program ANSYS. Once I understood the basic theory behind this analysis and working out a few computations by hand, I was able to use ANSYS to solve very complicated models.

In one homework assignment using ANSYS, we modeled a simple beam that was attached a a wall at one end and had a force pushing down at the other end. With ANSYS we can specify the type of material we are using (aluminum, steel, wood, etc.), the exact dimensions, any constraints (such as a wall holding one end fixed), and any forces on the beam. After this information is inputted into the program, we can have the computer calculate any information about the beam we want such as the max strain, max stress, and total deformation. One nice feature about this program is that we can create animations of how the beam deforms and display the magnitude of the stress.
Click here to view my short animation.

Even though ANSYS is very powerful in computing stress and strain on an object, we did not use it for all topics in this course. When studying bolts and springs, much of the analysis was done by hand. This is because we had to analyze more than just strain and stress, such as if the bolt or spring were long enough or thick enough and a computer program could not do that for us. For an example of how much analysis goes into designing and selecting proper bolts and springs:
Click here to view the solution to one of my exams (Adobe Acrobat required).