A mixed strain rate and energy based fatigue criterion for short fiber reinforced thermoplastics

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. This is an author-deposited version published in: https://sam.ensam.eu Handle IDMultiple parameters influence the durability of reinforced thermoplastics under fatigue loading. Having models unifying as many of these parameters, while providing an accurate estimation of the fatigue lifetime, is thus key. This investigation on the evolution of multiple mechanical parameters under cyclic loading, and based on a large experimental database (more than 200 uniaxial fatigue tests over a wide range of load ratios), two cyclic strainrate based criteria are proposed. The second is more elaborated, introducing anelastic energy, to better account for mean stress effect and unify fatigue life predictions within scatter bands of factor two.

Temperature effect on the mechanical properties and damage mechanisms of a glass/thermoplastic laminate

“…Technical thermoplastic polymers are being developed more and more as an alternative to non-recyclable thermosetting polymers. They are used as a matrix for composite materials mainly in the automobile [1][2][3] and energy 4 fields. Due to loading conditions such as dropped tools during assembly and maintenance, lowvelocity impact (LVI) or indentations are one of the major solicitations encountered by the composites throughout their service life.…”

Effect of severe thermo-oxidative aging on the mechanical behavior and fatigue durability of short glass fiber reinforced PA6/6.6

“…One of them is the loading rate, studied in fatigue and tensile testing, through the cycle frequency [9][10][11][12] and the stress-strain imposed rates [13], respectively. The load ratio also plays a major role in the fatigue behavior of such materials, particularly for extreme values [5,[14][15][16][17]. One of the consequences seen in tests performed under positive load ratio (tensile-tensile), is the so-called ratcheting effect, during which strain accumulates until complete failure of the specimens [9].…”

“…Recent studies compared both single-variable criteria (power-law) and multi-variable ones in a wide range of conditions including several load ratios (from -0.5 to 0.7) and different conditions (23 to 80 °C and 50 to 80% of relative humidity). Both Raphael et al [16] and Santharam et al [17] proposed criteria based on several fatigue indicator parameters (FIP): the hysteresis energy density, 𝑊 , the cyclic energy density, 𝑊 and the cyclic mean strain rate involved in the creep energy density, 𝑊 . Hence, following the same strategies as these studies, criteria based on imposed stresses [1,33] and derived energies [16,17,[34][35][36][37][38][39] were selected for comparison in a harsher environment.…”

Fatigue life assessment in notched injection-molded specimens of a short-glass fiber reinforced Polyamide 6 with different injection gate locations

“…This effect was widely evidenced in flat dogbone samples machined out of injected plates, in which the core-skin microstructure allows to define a major fiber orientation. Along with the better understanding of deformation and damage micromechanisms in uniaxially stretched samples in tension and fatigue [1][2][3][4][5][6][7][8], many efforts have been paid to improve lifetime estimation from criteria-based approaches [9][10][11][12][13][14][15][16]. On the other hand, composites fatigue lifetime is known to depend on stress concentrations too.…”