Several thin sandwich panels (thickness close to 3 mm) of different configurations were studied to explore an alternative material for the outer body of various machines and appliances such as automobile, refrigerator, washing machine, lathe machine, drill press, cupboards, light furniture, etc. Three types of sandwich panels with the outer face sheets made of glass fabric/epoxy were fabricated for the present study: (1) XM-Core panel was made of polyester foam Coremat XM/epoxy as core material, (2) Xi-Core panel was made of polyester foam Coremat Xi/epoxy as core material, and (3) J-Core Panel was made of layers of Jute fabric/epoxy as core material. A very thin transition layer of glass chopped strand mat/epoxy was provided between the face sheets and the core to improve their bonding strength. The sandwich panels were analyzed for low velocity normal impact loading under a drop weight impact test set up and transverse static loading under universal testing machine. Damage area, indentation depth and permanent depression over damage area, and failure modes were observed under incident impact loading. The transverse static test was performed to observe load versus deflection relation and to characterize the flexural strength and stiffness.

Glass fabric reinforced thin sandwich panel and carbon fabric reinforced thin sandwich panel of thickness close to 2.5 mm were studied to explore an alternative skin material for the outer body of various machines and appliances. The polyester foam Coremat XM of 2 mm thickness was used as core material in the thin sandwich panels. The panels were fabricated by vacuum bagging process and characterized through two plate tests: (i) low-velocity normal impact loading under a drop weight impact test set up and (ii) transverse static loading of a plate. The damage area, indentation depth and permanent depression over damage area, energy absorption capability, load-deflection relation and failure modes were observed under the test. The impact drop test was simulated by LS-DYNA. The properties of glass fabric reinforced thin sandwich panel and carbon fabric reinforced thin sandwich panel were compared with those of 0.8-mm-thick MS sheet, a widely used skin material for the outer body of various machines and appliances.

The present study is an attempt to take an overview of the work done in the area of characterization of polymer composite materials, different constituent materials used in polymer composites, failure mechanism and manufacturing process of polymer composite. Based on comprehensive literature review of various aspects in developing polymer composite materials, it is observed that extensive work has been done related to monocoque structure and thick polymer sandwich panels, whereas studies carried out to analyse static and dynamic strength of thin polymer sandwich panels are limited. The behaviour under flexural loading and impact loading, and interlaminar fracture toughness of laminated polymer composite are the main areas of interest of researchers.