Force‐transducer‐design Optimization for the Measurement of Die‐wall Stress in a Compaction Simulator

A novel slotted-web transducer design concept for the measurement of die-wall stress in a compaction simulator has been developed and optimized by use of computer-aided design procedures. The optimized design was then built and tested. Geometric optimization of the novel design configuration and determination of strain-gauge placement were performed so that the transducer could withstand the high die-wall pressures encountered in a compaction simulator. Stress analysis was performed with Algor, a finite-element analysis software package. A model prototype was constructed with 4140 alloy steel and heat treated to a hardness of 43 Rockwell C. This prototype had a linear calibration curve (r2 = 0.99) at three different punch settings with no hysteresis. Radial stress versus axial stress transmission curves, and results from measurement of residual die-wall stress for dibasic calcium phosphate dihydrate, mannitol, sodium chloride, paracetamol and starch were consistent with literature data, which indicates satisfactory transducer performance.