Axial crush simulation of composites using continuum damage mechanics: FE software and material model independent considerations
TL;DR: In this paper, the authors investigate three different material models based on continuum damage mechanics (CDM) within two commercial finite element (FE) software packages, ABAQUS/EXPLICIT and LS-DYNA, to identify FE-code and material model-independent capabilities, limitations and challenges of physically-based axial crush simulation of composite structures without the use of non-physical parameters for model calibration.
Abstract: The finite element (FE) simulation of industrial size composite structures under crush loading is a challenging task. Currently, the vast majority of these simulations employ non-physical “tweaking” parameters that are undesirable and limit the confidence in their predictive capabilities. This paper investigates three different material models based on continuum damage mechanics (CDM) within two commercial FE software packages, ABAQUS/EXPLICIT and LS-DYNA, to identify FE-code and material model-independent capabilities, limitations and challenges of physically-based axial crush simulation of composite structures without the use of non-physical parameters for model calibration. In particular, we show that the commonly applied crack band scaling in CDM-based material models is not suitable for the simulation of axial crushing where the dominant mode of failure is fragmentation.
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TL;DR: In this paper , high-fidelity computational modeling of the dynamic impact response was performed using explicit finite element analysis in LS-DYNA, and the numerical predictions showed excellent correlation with experimental measurements in terms of both the damage mechanisms and macroscopic material behaviour of the drop weight.
Abstract: Angle-ply carbon fibre reinforced polymer (CFRP) crush tubes were tested in drop weight impact experiments. High-fidelity computational modelling of the dynamic impact response was performed using explicit finite element analysis in LS-DYNA. Ply-by-ply and fibre-aligned meshing was used for the composite lamina wherein the intralaminar damage was treated with a 3D rate- and pressure-dependent continuum damage mechanics (CDM) model, implemented as a user material. Delamination was modelled using cohesive tiebreak contacts to deal with the mis-matched nodes caused by the use of a structured, fibre-aligned mesh. The material aligned meshing scheme was shown to be required to capture the intralaminar splits observed in the ±45∘ plies. The numerical predictions showed excellent correlation with experimental measurements in terms of both the damage mechanisms and macroscopic material behaviour of the drop weight. In the simulation, interlaminar friction between delaminated plies seemed to be a main contributor of energy dissipation. Parameter sensitivity analysis showed that the interaction between the delamination fracture energy and friction can substantially influence the results and stable crushing load, in particular. For the scenario studied here, a regular structured mesh (unaligned) was shown to be insufficient for simulating realistic crack paths despite producing reasonable predictions of the force–displacement and absorbed energy.
7 citations
TL;DR: In this paper , a novel approach to physically motivate the damage evolution parameters in LS-DYNA material model *MAT_058 for numerical predictions of strain-rate-dependent damage in composites is presented.
5 citations
TL;DR: In this paper , a systemic calibration methodology is presented to efficiently simulate progressive damage evolution in four different pultruded glass fiber reinforced polymer (GFRP) composites using the strain-based COMposite DAMage Model (CODAM2) in the commercial finite element software LS-DYNA.
Abstract: This paper presents a systemic calibration methodology to efficiently simulate progressive damage evolution in four different pultruded glass fiber reinforced polymer (GFRP) composites using the strain-based COMposite DAMage Model (CODAM2) in the commercial finite element software LS-DYNA. In particular, Compact Tension (CT), scaled-up CT, and wide CT tests are simulated to find the best set of input parameters by considering four distinct indicators obtained from experimental and numerical load vs displacement data. By combining these indicators into a physically meaningful equivalent deviation value via a linear weighted-sum method, the results show that the most suited input damage variables yield physically accurate crack length predictions which underlines the robustness and accuracy of the proposed method. Furthermore, it is shown that the incorporation of bi-linear softening laws improves CODAM2 simulation results by up to 90%, however it also increases the number of parameters to be calibrated.
4 citations
TL;DR: In this paper , a review analyzes the important factors affecting the static and dynamic performance optimization of composite helical springs from the perspectives of theory, finite element method (FEM), and experiment.
Abstract: Composite helical springs (CHSs) are mainly used in transportation and aerospace fields, such as automobile suspension, railway bogie and aircraft engine systems. It has become a trend to replace the traditional metal helical springs with CHSs with the advantage of energy conservation during service and emission reduction during manufacturing. The advantages of CHSs such as low weight, high specific strength, high specific modulus, corrosion resistance, fatigue resistance and high strain energy storage capacity mean that it has great development potential. The static and dynamic performances of CHSs together determine whether they can be used on a large scale in the engineering field. The static performance of the CHS determines their service-load range and the dynamic performance determines the service life and safety performance of CHSs under dynamic load environmental conditions. Therefore, it is an important task to optimize the static and dynamic performance of CHSs. To provide a reliable reference for the development of CHSs, this review analyzes the important factors affecting the static and dynamic performance optimization of CHSs from the perspectives of theory, finite element method (FEM), and experiment. In addition, the outlook in the research of CHSs are discussed.
4 citations
TL;DR: In this article , thin quasi-isotropic [90/45/0/−45]s Beech veneer laminates were subjected to a range of mechanical tests derived from fibre-reinforced counterparts.
3 citations
References
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01 May 1983
TL;DR: In this article, a fracture theory for a heterogenous aggregate material which exhibits a gradual strain-softening due to microcracking and contains aggregate pieces that are not necessarily small compared to structural dimensions is developed.
Abstract: A fracture theory for a heterogenous aggregate material which exhibits a gradual strain-softening due to microcracking and contains aggregate pieces that are not necessarily small compared to structural dimensions is developed. Only Mode I is considered. The fracture is modeled as a blunt smeard crack band, which is justified by the random nature of the microstructure. Simple triaxial stress-strain relations which model the strain-softening and describe the effect of gradual microcracking in the crack band are derived. It is shown that it is easier to use compliance rather than stiffness matrices and that it suffices to adjust a single diagonal term of the complicance matrix. The limiting case of this matrix for complete (continuous) cracking is shown to be identical to the inverse of the well-known stiffness matrix for a perfectly cracked material. The material fracture properties are characterized by only three parameters—fracture energy, uniaxial strength limit and width of the crack band (fracture process zone), while the strain-softening modulus is a function of these parameters. A method of determining the fracture energy from measured complete stres-strain relations is also given. Triaxial stress effects on fracture can be taken into account. The theory is verified by comparisons with numerous experimental data from the literature. Satisfactory fits of maximum load data as well as resistance curves are achieved and values of the three material parameters involved, namely the fracture energy, the strength, and the width of crack band front, are determined from test data. The optimum value of the latter width is found to be about 3 aggregate sizes, which is also justified as the minimum acceptable for a homogeneous continuum modeling. The method of implementing the theory in a finite element code is also indicated, and rules for achieving objectivity of results with regard to the analyst's choice of element size are given. Finally, a simple formula is derived to predict from the tensile strength and aggregate size the fracture energy, as well as the strain-softening modulus. A statistical analysis of the errors reveals a drastic improvement compared to the linear fracture theory as well as the strength theory. The applicability of fracture mechanics to concrete is thus solidly established.
3,102 citations
TL;DR: In this article, an operationally simple strength criterion for anisotropic materials is developed from a scalar function of two strength tensors, which satisfies the invariant requirements of coordinate transforma tion, takes into account the difference in strengths due to positive and negative stresses, and can be specialized to account for different material symmetries, multi-dimensional space, and multi-axial stresses.
Abstract: An operationally simple strength criterion for anisotropic materials is developed from a scalar function of two strength tensors. Differing from existing quadratic approximations of failure surfaces, the present theory satisfies the invariant requirements of coordinate transforma tion, treats interaction terms as independent components, takes into account the difference in strengths due to positive and negative stresses, and can be specialized to account for different material symmetries, multi-dimensional space, and multi-axial stresses. The measured off-axis uniaxial and pure shear data are shown to be in good agreement with the predicted values based on the present theory.
3,030 citations
TL;DR: In this article, a progressive damage model for notched laminated composites subjected to tensile loading is presented, which is capable of assessing damage in laminates with arbitrary ply-orientations and of predicting the ultimate tensile strength of the notched Laminates.
Abstract: A progressive damage model is presented for notched laminated composites subjected to tensile loading. The model is capable of assessing damage in laminates with arbitrary ply-orientations and of predicting the ultimate tensile strength of the notched laminates. The model consists of two parts, namely, the stress analysis and the failure analysis. Stresses and strains in laminates were analyzed on the basis of classical lamination theory with the consideration of material nonlinearity. Damage accumulation in laminates was evaluated by proposed failure criteria combined with a proposed property degradation model. A nonlinear finite element program, based on the model, was developed for lami nates containing a circular hole. Numerical results were compared with the experimental data on laminates containing an open circular hole. An excellent agreement was found be tween the analytical prediction and the experimental data.
1,162 citations
TL;DR: In this paper, a constitutive model for anisotropic damage is developed to describe the elastic-brittle behavior of fiber-reinforced composites and the corresponding rate-equations are subjected to the laws of thermomechanics.
1,099 citations
TL;DR: In this article, a model of fibrous composite laminate damage is modelled at the elementary-ply scale, where damage mechanics are used to describe the matrix microcracking and fiber/matrix debonding.
839 citations