Shear Constitutive Behavior of Closed-Cell PVC Foams at Varied Loading Rates

Abstract Closed-cell polymeric foams are increasingly being used in the sandwich composite construction of marine and transportation industry, due to their lightweight, good resistance to moisture absorption and better energy dissipation capacity. During their use in sandwich structures these cellular materials are subjected to compression and shear deformation due to transverse loading. Thus, understanding the shear constitutive behavior of these polymeric foams is important for practical applications. The shear constitutive behavior of the closed-cell PVC foam (in foam rise direction) was experimentally evaluated at three different loading rates, varying from $${10}^{-3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> to $${10}^{3}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mn>3</mml:mn> </mml:msup> </mml:math> /s for different grades of foam (H45, H80, and H130). Quasi-static and intermediate loading rates were achieved through a Universal Testing Machine (UTM) and high loading rate was applied using modified Split Hopkinson Pressure Bar (SHPB) apparatus. For shear behavior, 2D Digital Image Correlation (DIC) technique was used to measure the full-field strain on the specimen surface. The results showed that the shear strength as well as the crushing strength of the closed-cell PVC foams increases with increase in the loading rate. However, the rate of increase in strength shows contrasting trends for the shear and crushing behavior. Also, the shear strength of the PVC closed-cell foam along the foam rise direction is less than 50% of the crushing strength, at respective loading rate.