Shear stress during manufacturing of structural composite materials

Characterization and modeling of shear stress during manufacturing and thermal properties of structural composite materials: An experimental methodology is presented to determine tool-part frictional interaction of composite parts and the structural integrity of sandwich structures when subjected to temperatures and pressures similar to those of autoclave processing. This methodology includes the development of a testing rig that mimics the deformation mismatch between tools and parts, and quantifies shear stress-that is, tool-part friction or shear stress of sandwich structures. Discrete and continuous friction characterization was performed to validate this testing methodology, and a semiempirical mathematical model was obtained to predict the tool-part frictional interaction as a function of different manufacturing variables including temperature, pressure, and part length. Moreover, a characterization of the shear strength of sandwich structures is presented where results indicate a strength decrease when temperature and pressure increase following an inverse-exponential trend for both cases.