Homework Assignment 5
Design and Analysis of the Mechanical Part of a Postal Scale
Due Date: 8:00 am, Monday, October 21, 1998

Description: When you go to a local post office, you may notice that a postal scale is used to determine the postage needed. In general, the postage is electronically displayed. The weight of a package to be mailed is one of the several factors to be considered. This assignment is asking you working as a team to design the mechanical part of a postal scale. Your design is limited to use strain gages as sensors. Each team will be given four strain gages as the maximum number. Your team is also responsible for making a prototype of the key component so that strain gages can be installed on it. A calibration curve should be obtained, indicating the relationship between the weight and the readings from a strain gage meter. It is very important that you know that the raw material is available to you. You need to think about the testing environment. Otherwise, you may experience difficulties at the time you test your design.

This is a two-week assignment. In the first week, each team should complete the design and analysis. ANSYS is required to perform analyses of stress and strain of the component. Using Pro/MECHANICA is also required to perform the analysis. Compare the two FEA systems. In your team report, state the merits and drawbacks of each system. In the second week, making the prototype, testing your prototype, and writing the final report.

For your reference, product specification of a postal scale prepared by an instructor who is teaching ENES 100 this fall is attached. Some of initial results from a feasibility study are also attached.