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Effects of Density and Cell Rise Ratio on 3D Failure Strengths of Rigid PVC Foam in Different Loading Modes and Loading Directions



A study was conducted to investigate the important effects of foam density and cell rise ratio on failure strength of rigid closed-cell PVC foams. Experiments were performed on test samples made from an as-received Divinycell H100 PVC foam panel which had relatively large density variations in both planar and through thickness directions. With the inherent foam density variation that existed in the foam panel, tension, compression and shear specimens with different foam densities were prepared, which eliminated the possible effect of variation in processing conditions on foam strength. Recently developed accurate 3D foam test methods by the authors were employed in the study for the foam strength determination. Foam failure strengths in both out-of-plane and in-plane directions were determined. The effects of foam density and foam cell rise ratio on the foam in-plane and out-of-plane strength properties are found to be significantly different. To augment the experimental study a recently developed predictive models for foam compression, tension and shear strengths were used to further investigate the effects of foam density (r) and foam cell rise ratio (b) on the measured foam failure strengths. Good agreements are found between the experimentally determined and theoretically predicted foam strengths for all loading modes in different loading directions. The importance of the combined effects of foam density and cell rise ratio on foam failure strengths is clearly demonstrated. The results of the present study on foam strength and our earlier results on foam stiffness show that for in-plane and outof- plane foam shear strengths, foam density r is the governing parameter. For out-ofplane and foam compression and tensile strengths, (=br) is the key parameter that must be used to provide accurate description of closed-cell PVC foam strength and stiffness.


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