Multi-scale experimental investigation of the viscous nature of damage in Advanced Sheet Molding Compound (A-SMC) submitted to high strain rates

Abstract

This paper aims to present an experimental multi-scale analysis of quasi-static and high strain rate damage behavior of a new formulation of SMC composite (Advanced SMC). In order to study its capability to absorb energy through damage accumulation, Randomly Oriented (RO) and High oriented (HO) A-SMC composites damage has been investigated at both microscopic and macroscopic scales. A specific device has been developed in order to perform Interrupted Dynamic Tensile Tests (IDTT) which allows analyzing the evolution of the microscopic damage mechanisms occurring during rapid tensile tests. Several damage micro-mechanisms have been pointed out. The relative influences of these micro-damage events and their interactions have been related to the macroscopic damage behavior through the definition of microscopic and macroscopic damage indicators. Damage threshold and kinetic have been quantified at various strain rate for different microstructures and loading cases (RO, HO-0 and HO-90). It has been shown at both scales that increasing strain rate leads to an onset of damage initiation together with a reduction of the damage accumulation kinetic. Moreover, the influence of the fiber orientation has been studied in order to emphasize the anisotropic strain rate effect at the fiber-matrix interface scale. The latter was related to the influence of the microstructure of A-SMC composites. Finally, on the basis of the whole experimental results, the microscopic origin of the viscous nature of the damage behavior of A-SMCs composites have been discussed and related to the influence of the strain rate and microstructure.

Multiscale damage analysis of the tension‐tension fatigue behavior of a low‐density sheet molding compound

“…To formulate the equation of SMC composites, it is necessary to have enough information about mechanical properties and especially damage phenomena under different modes of loading such as monotonic or fatigue. 10,11 Fatigue response of composites is usually characterized by the Wöhler curve, which is a curve giving the value of cyclic stress/strain amplitude versus the number of cycles to failure, N. 2,[12][13][14][15][16] The parameters that can affect the cyclic behavior are fiber orientations, applied stress/ strain, temperature, frequency, and self-heating. 2,[14][15][16] Strain rate and temperature are two important parameters, which effect on material behavior under different solicitation modes such as tension, compression, shear, and torsion.…”

“…In SMCs, the bestknown damage mechanisms are matrix cracking, interfacial debonding: the interface between fibers and matrix, pull out or tearing, fiber breakage and delamination between layers for laminated composites. 10,17,[22][23][24] The risk of these damages is that they are sometimes undetectable to the naked eye as their location internal to the structure. Depending on the distribution and the geometry of the components in the matrix, the SMC composite will exhibit anisotropic behavior.…”

Experimental and numerical multi-scale approach for Sheet-Molding-Compound composites fatigue prediction based on fiber-matrix interface cyclic damage

“…On the other hand, for discontinuous fiber reinforced polymers, a lot T of studies have revealed that the fiber-matrix interface failure can be defined as the predominant local damage mechanism [13][14][15][16][17][18][19][20][21][22]. The experimental analysis has revealed that local damage generally begins by debonding the most misoriented fibers when the local normal stress reaches a critical value.…”

“…Then, it progressively propagates to less misoriented fibers by coupling normal and shear interface stresses [15]. Under tension, damage initiation is generally observed for 20% to 30% of the failure stress [14][15][16][17][18][19][20][21][22]. For short fiber reinforced thermoplastic, the ductility of the matrix around the fibers leads to diffuse microcracking.…”

Proposal for a composite structure and graphic design for a parking barrier

“…Many researchers studied the mechanical behavior of a glass fiber reinforced composite and presented their connection with the fiber strength and modulus, fiber weight fraction, orientation, type, chemical stability, matrix strength and the interface bonding between the fiber and the matrix [12][13][14][15][16][17][18].…”