Design and validation of new testing apparatus for testing helical compression springs under combined axial, shear, torsion, and bending loads.

Helical compression springs are normally used to provide a linear force response to compressive displacement. However, compression springs can be used to provide lateral force and rotational torque responses to lateral and angular displacements. The purpose of this thesis is to take advantage of improvements in mechanical testing equipment to develop a testing apparatus that can mechanically test helical compression springs under varying amounts of complex three-dimensional displacements. A testing apparatus was constructed using a custom six axis load cell and a commercial MTS system. The calibration and validation of the custom load cell is presented. One compression spring was tested under different combinations of axial, shear, and torsional displacements to validate the design of the jig. The results indicated varying levels of interdependence between the loading modes on the spring’s net force response; however, the spring’s compressive response appears to be independent of torsion and shear displacement.