Induction melt thermoforming of advanced multi-axial thermoplastic composite laminates

The viability of using induction heating to facilitate the wrinkle-free forming of multi-axial pre-consolidated advanced thermoplastic composites over complex geometries is explored. The research focuses on the use of tin as a medium to both heat and lubricate the forming laminate. Initial tests demonstrate the viability of the fundamental ideas of the process; induction heating is used to melt the tin sheet, which is then shown to melt the matrix phase of carbon-nylon composite laminates when stacked in a hybrid composite/tin layup. A novel low-cost reconfigurable multi-step forming tool is used to demonstrate how most of the tin can be squeezed out of the layup prior to consolidation. The multi-step tool can be augmented with segmented tooling to rapidly manufacture composite parts of high geometric complexity. In this investigation, a 'ripple' geometry containing three 'cavities' is used to demonstrate the technique. Tests demonstrated that at least three sheets of inter-laminar tin can be simultaneously melted using the induction heating system. Initial results indicate complex geometries can be formed with minimal wrinkling while removing interlaminar tin

Jahresbericht 1980 der Informatik

SIGLEDEGerman

Measurements of pressure and area dependent tangential contact stiffness between rough surfaces using digital image correlation

The present paper describes an experimental technique to accurately measure the tangential contact stiffness between two rough contacting surfaces manufactured from the titanium alloy Ti–6Al–4V. The digital image correlation method is employed to measure the local displacement field. The effect of normal contact pressure, nominal contact area and fretting wear on tangential contact stiffness is investigated. The experiments indicate that the tangential contact stiffness is approximately proportional to the nominal contact area and the normal pressure raised to the power of 0.64. Multiple experiments with the same parameters show good repeatability given the number of variables involved