Analysis of fatigue phenomena on Composite core Sandwich Panels life under Three-point Bending Loading

The use of sandwich panels has become very popular in recent engineering designs when the weight of the piece or structure is important and we want to reduce weight. Mechanical properties of these types of structures, including yield stress, fatigue behaviour and life estimation, failure modes, natural frequencies and resonance phenomena, etc., are influenced by various factors, including geometric and environmental factors. In this study, influences of geometric factors, loading frequencies and initial crack position on the fatigue life of composite sandwich panels and their failure modes are investigated using numerical and experimental methods. The research consists of two parts including numerical analysis using finite element software and experimental tests in which the samples are under three-point bending loads. Experimental specimens consisted of an XPS-foam core and fibre-glass were used as face sheets. The results showed that by reducing the width of the beam, final life of the samples reduced linearly and crack propagation and final failure mode of different samples were different with each other. Reducing width of beams from ۱۰cmm to ۸cm and ۶ cm, caused a ۲۳% and ۴۸% reduction in sample’s life. By enhancing distance of the initial crack from the centre of the beam, the life of the samples increased and apparently within a different final fracture mode in specimens. A ۲.۵cm and ۵cm distance in crack’s location from beam’s centre caused ۱۰% and ۱۶% enhancement in sample’s life, respectively compared with the sample which the initial crack was in the centre of the beam.

Keywords:

Sandwich Panel , Finite Element , Fatigue , Composite , Three-point Bending