Design, development, and testing of load cell accelerometers

As part of an instrumentation and measurement theory course for third-year Mechanical Engineering students, accelerometers were produced using a mini load cell beam (100 grams max) as the sensing element. The students worked in small teams to design, develop, and test a custom accelerometer with a measurement range of ±4 g. Although using a load cell does not represent a practical approach to modern accelerometer design, it does provide a means for investigating many of the design considerations and concepts required to understand accelerometer operation. The students were given specifications for the accelerometer and made design tradeoffs and decisions to meet the requirements. Students were also required to develop and implement a test procedure to verify specification compliance. A modest budget was provided to allow the design teams to purchase materials. The campus machine shop is very well equipped and staffed and was available to help fabricate custom parts. 3-D printing of parts was also an option for the teams to use. An instrumentation amplifier circuit board kit was available for the students to integrate into their design. The project provided a very good means of unifying many aspects of the course. The fabrication experience gained through this project is also a valuable component of the mechanical engineering curriculum. This paper presents examples of student accelerometer designs and data from prototype testing. Equipment and methods used to test the prototypes are also presented and discussed.