Semester 2Â 2021
Project Progress
CAD Designs
A number of different clamp jaw designs and operating mechanisms have been investigated. See our repository for the modified CAD design files, images and a some insight into our concept generation process.
Review of Sensor Technologies
Literature on different mechanical and electrical sensors was surveyed, particularly those that have been used in medical applications, to inform the team's sensor design, concept generation & evaluation. See our repository for a summary of this research.
Torque Wrench Working Principle
A design based upon the working principles of a torque wrench was explored by the team, which received a very positive reception by the client. The mechanical set-up of this problem and some preliminary torque calculations have been devised. See the literature review for further detail on how mechanical beam and dial torque wrenches operate, and click here to see our initial formulation of the problem.
Instrumented Clamp CAD Model
After formulating the deflecting beam design mechanically, the next step was to integrate the scale and needle elements into the existing clamp model to generate a prototype of the concept (shown in the image at right). See the CAD model here.
Bone Contact Stress Finite Element Analysis
One of the most important considerations for this project is patient safety. For this reason, the team performed FEA on the contact points under healthy, osteopenic and osteoporotic conditions to determine the range of safety limits for the current design. Using the original clamp jaw structure, this was evaluated to be 100N if aiming for a factor of safety of 3. See our results here.
Clamp Deflection Finite Element Analysis
FEA was also used to demonstrate how the developed concept would work in practice. A 20 Nm torque at the knee and 1800N force at the handle produced the reading shown in the top image, while a 700N force produced the bottom deflection. This analysis shed light on further considerations that need to be made with regard to geometry and material choice to ensure the desired results are achieved. See the results here.
Arduino Programming for Piezoelectric Sensor
To get a head-start on the testing & validation of electronic sensor options, the team programmed an Arduino to display the pressure recorded by a piezoelectric long bar sensor on an LED screen. See the code here.