Experimental investigation of thermal effects in foam cored sandwich beams

Abstract

Polymer foam cored sandwich structures are commonly used in applications where mechanical loads and elevated temperatures form the normal service conditions. The temperature sensitivity of the mechanical properties of the polymer foam cores leads to compromised mechanical performance of the overall sandwich structure at elevated temperatures. So far this phenomenon has primarily been investigated using analytical techniques. The present paper provides a basis for experimental studies of the temperature sensitivity of sandwich structures through the design of a test rig that can simulate the mechanical and thermal conditions experienced in service. The sandwich structure is modelled as a simple beam specimen with the mechanical load introduced using a standard servo-hydraulic test machine. A fixture has been specially designed that can apply a variety of constraints. A through thickness temperature gradient is introduced to the beam via an infrared (IR) radiator applied to one face sheet. The rig is designed to accommodate non-contact full-field techniques. An infrared detector is used to obtain the temperature field and high resolution white light cameras to capture the displacement using digital image correlation (DIC). An arrangement of mirrors enables both the face sheet and through-thickness surfaces to be viewed. The paper presents the design and evaluation of the rig, together with initial data obtained from a PVC foam cored sandwich specimen with aluminium face sheets.