Advances in composite forming through 25 years of ESAFORM

Abstract

The increase in the number of structural applications of composite materials, especially in the aerospace and automotive industries, has led to a demand for robust models to simulate composite forming processes. The mechanical behaviour of composite materials during forming is relatively complex due to their fibre-matrix composition. Many research studies have been conducted in the past 25-plus years into experimental methods for the characterization of the mechanical behaviours that are exhibited by textile-reinforced composite material systems during forming and into the development of material models to be used in computer codes for forming simulations. These studies have been presented and discussed in the ESA-FORM conferences since 1997 and especially in the 'Composite Forming Processes' mini-symposium launched in 2001. This article presents a survey of the research carried out in this context. Mechanical characterization tests specific to composite forming are presented as well as recent analysis techniques such as digital image correlation and X-ray tomography. Threedimensional mechanical behaviour laws, in particular hypo-and hyperelastic, have been developed and extended to second gradient models. Specific shell approaches have been presented and their application to wrinkling analysis. Resin flow and permeability analysis is another area of research in composite forming processes which are discussed in this article. Research on certain processes is also presented, in particular thermoforming of thermoplastic composites, wet compression moulding, pultrusion, automated fibre placement and three-dimensional printing. This comprehensive review of the works of multiple research groups is a recognition of the breadth and depth of efforts that have been invested into the understanding of the manufacturability of textile-reinforced composite materials.

Surrogate model of the thermoforming of fiber reinforced thermoplastics

“…A disadvantage of the material card is the lack of options for implementing bending stiffnesses. For numerical models using shell elements, the stiffness is unrealistically high, due to the fact that in classical approaches such as the Kirchhoff theory, the bending stiffness is given by the tensile stiffness and thickness while slippage between fibers leading to lower bending stiffness is not considered [11]. Therefore, the bending behaviour is adjusted through the position and number of integration points to the neutral axis of the sheet [12].…”

Investigation on the pultrusion of thermoplastic preimpregnated polypropylene-glass tapes

“…Pultrusion is a widely consolidated process for the manufacturing of constant cross-section profiles in continuous fibers reinforced thermoset [1]. The success of this process is related to several factors: i) the high tensile properties due to the orientation and the volume fraction of the reinforcement; ii) the continuous nature of the process, which in turn guarantee high productivity, repeatability, and automation; iii) the low energy and human intervention required; iv) low or null waste of raw materials [2,3].…”

Automated programming for the robotic layup process

“…Advantages properties of fiber reinforced polymers (FRPs) have promoted their wide usage in several applicative sectors, ranging from aerospace, automotive, through to naval and construction industries [1] to improve the performance and reduce the weight of their components [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Advanced FRPs are multi-phase materials made of continuous reinforcing fibers, oriented in one or more specific direction, embedded within a polymeric matrix.…”