Determining effective interface fracture properties of 3D fiber reinforced foam core sandwich structures

Abstract

Foam core sandwich composites are finding a wider use in aerospace, automotive, and construction applications. These structures present unique challenges in terms of material failure and interaction and are sensitive to damage and imperfections introduced during manufacturing. An emerging class of 3D fiber reinforced foam core aims to replace monolithic foams used in sandwich structure cores particularly in demanding high-performance aerospace applications. This research is focused on investigating the development of testing methods capable of measuring the effective interface fracture properties between the facesheet and the core in 3D fiber reinforced foam cores. Double cantilever beam and end-notched flexure specimens are developed to evaluate the mode I and mode II fracture properties of a 3D fiber reinforced foam core. The design, development, and initial failure of a mode I interface fracture test for 3D fiber reinforced foam cores are presented. The digital image correlation results on the failed tests allowed for a different approach to be utilized in designing a new bonded double cantilever beam specimen for testing the mode I fracture of a 3D fiber reinforced foam core sandwich structure that resulted in a successful interface fracture test. The bonded DCB specimens exhibited relatively smooth crack propagation and produced GIc values similar to honeycomb sandwich structures and significantly higher than comparable foam structures.

Experimental and numerical study of delamination phenomenon in sandwich structures with hybrid corrugated core in the mode II of crack growth

“…Kier and Waas 11 studied the effects of a three-dimensional fiber-reinforced foam core (3DFRFC) on the fracture and delamination of sandwich panels. They performed DCB and three-point bending tests in the mode I and mode II failure.…”

Experimental and theoretical research on four-point bending performance of Nomex honeycomb sandwich panels

“…[19][20][21] The theoretical prediction models of each failure mode have also been constructed. 22,23 With the increasing requirements for lightweight and designability in various industries, composite sandwich panels are expected to be widely used. Nomex honeycomb sandwich panels (NHSP), as a typical representative, have been extensively analysed and studied.…”

Preparation and Properties of a Novel High-Strength Foam

“…In general, the compressive strength and thermal stability of usual foams are low, which limits their applications. With the development of technology, like the increase of the speed of spacecraft in the aerospace field, the requirements of mechanical property and thermal stability for foam material are higher [10].…”