Fracture toughness and crack resistance curves for fiber compressive failure mode in polymer composites under high rate loading

Abstract

Koerber, H. (2017). Fracture toughness and crack resistance curves for fiber compressive failure mode in polymer composites under high rate loading. Composite Structures, 182,[164][165][166][167][168][169][170][171][172][173][174][175] This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. The results show that the steady state fracture toughness of the fiber compressive failure mode of the unidirectional carbon-epoxy composite material IM7-8552 is 165.6 kJ/m 2 and 101.6 kJ/m 2 under dynamic and quasi-static loading, respectively. Therefore the intralaminar fracture toughness in compression is found to increase with increasing strain rate.

Determination of the crack resistance curve for intralaminar fiber tensile failure mode in polymer composites under high rate loading

“…The calculated R-curves for fiber tensile failure show, that the steady-state 460 value of the fracture toughness and the length of the fracture process zone increases with increasing strain rate, therefore exhibiting the same tendency as found for the fiber compressive failure mode [38]. Along with experimental data presented in [38,51,54,59,60], the results obtained in the present study complete a comprehensive dynamic material data set for the carbon-epoxy material 465 IM7-8552, which may be used for simulations of dynamic load scenarios and the further development of composite material models.…”

“…3, the R-curve is the envelope of the energy release rate curves for different specimen sizes, w k , at the corresponding peak loads, P uk . Figure 3: Energy release rate curves G Ik for different specimen sizes at respective peak load P uk and R-curve (after [38]).…”

“…A methodology to measure the mode I dynamic intralaminar R-curve for compressive fiber failure was recently proposed by Kuhn et al [38]. Using a split-Hopkinson pressure bar (SHPB), which is a widely-used setup for dynamic 40 fracture tests [39], the R-curve for fiber compressive failure was determined for the carbon-epoxy material IM7-8552 by testing double-edge notched compression (DENC) specimens of different sizes at a strain rate of about 100 s −1 .…”

Experimental characterization and constitutive modeling of the non-linear stress–strain behavior of unidirectional carbon–epoxy under high strain rate loading

“…The presented test data complements static and dynamic experimental results from earlier and recent studies for the same material system, namely [2], where off-axis compression and transverse compression tests were performed [3,4], where the longitudinal compressive response was studied and [5], where the effect of dynamic loading was investigated for the intralaminar fracture toughness associated with fiber compressive failure.…”

Determination of mode I dynamic fracture toughness of IM7-8552 composites by digital image correlation and machine learning

“…The CT specimen ( [9] [10] [11], among others) and the size effect method [12] have been used to measure the R-curve associated with the propagation of a kinkband. Despite the work performed so far only one paper [13] has been published on the determination of dynamic compressive failure for fiber-reinforced composites.…”