In this paper, a 3D finite element model is established in ABAQUS/Explicit based on a modified progressive damage model to study the dynamic mechanical response and damage development in cross-ply composite laminates subjected to low-velocity impact. The 3D Hashin criterion and the damage evolution model with the through-thickness normal stress component σ 33 are applied to predict the intra-laminar damage initiation and evolution. The cohesive elements with the bilinear traction-separation relationship are inserted between layers to predict the inter-laminar delamination induced by impact loading. A user-material subroutine VUMAT involving the modified progressive damage model of intra-laminar and inter-laminar damage is coded and implemented in the finite element package ABAQUS/Explicit. The numerical results of three different impact energies (7.35, 11.03 and 14.70 J) are analyzed by the impact force-time, force-displacement and energy-time histories curves as well as different damage modes. The respectable relationship between numerical simulation and experimental result indicates that the proposed modified method is more suitable for low-velocity impact on composite laminates under different impact energies than the previous method without σ 33. Moreover, the effects of S mt and S mc on global mechanical response and local damage predictions for laminates are discussed in detail. It can be concluded that both of the coefficients should be adopted between 0.93 and 0.96 when using this damage model to simulate composite laminates under low-velocity impact.
The dynamic mechanical responses and damage development of cross-ply composite laminates under repeated low-velocity impact are investigated through finite element simulations with ABAQUS/Explicit. A progressive damage model for laminates, consisting of the continuum damage model, the 3D Hashin failure criterion and the damage evolution model based on equivalent displacement, is integrated with the bilinear traction-separation relationship cohesive model to simulate the damage initiation, evolution and propagation behavior of different damage modes in composite laminates. Compared with the experimental results, the established finite element model was validated through the global mechanical response and damage distribution contous. Besides, a mesh refinement study was performed by using three different element sizes. The validated model was adopted to investigate the repeated impact behaviors of composite laminates under three different energies. The qualitative conclusions about the effects of repeated impact on global mechanical response were summarized by the changes of impact force, displacement, contact time and energy absorption. Moreover, the effects of repeated impact on the damage characteristics and expansions of matrix and delamination were discussed in detail.
This paper describes an analytical model for predicting trapezoid tearing strength of flexible woven composites. The analytical model was established based on the tearing damage behavior of the flexible woven composite sample during experimental tests. It was observed during the test that the tearing force increased gradually with the increase of the tearing delta zone. The analytical model involves the formulation of the strength sustained by the fiber bundles (warp yarns and weft yarns) and coatings, respectively. Based on the analytical model, the tearing deformation at different tearing delta zones has been calculated to derive the tearing strength at different displacements. The model was validated from the good agreement between the calculated results and the experimental results. From the model, it was found that the failure strain and the elastic modulus of the yarn as well as the weaving density of the fabric are the key factors affecting the tearing strength of flexible woven composites. It is expected that the analytical model could be extended to the design of flexible woven composites with a high tearing resistance, such as flexible pipelines and architecture membranes.
2016)Thermal-structural analysis of large deployable space antenna under extreme heat loads, Journal of Thermal Stresses, 39:8, 887-905, ABSTRACT Large deployable space antennas may be exposed to severe thermal environments in future space missions; extreme heat loads will result in considerable thermal stresses and deformations which seriously a ects the accuracy of the antenna's parabolic surface. In this study, thermal-structural nite element analysis of a deployable AstroMesh antenna under extreme heat loads was presented. Considering position and orientation with respect to the Sun and Earth, the antenna's temperature changing law under orbital heat uxes was rst evaluated to nd the worst condition as loading point. Analyses for the antenna under di erent levels of extreme heat loads were then performed to obtain the temperature distributions utilizing an equivalent quarter antenna model. Based on the temperature calculation results and prestress designs, structural analyses were nally made to gain the resulting stresses and deformations. The analysis results show that the existing antenna may generate signi cant performance distortion under extreme thermal environments; so attentions for reliability and safety under such conditions should be taken seriously in future antenna works. Modeling and analysis method proposed in this article was validated to be contributive in antenna's thermal and precompensation designs. ARTICLE HISTORY
In this work, an improved computational method for the prediction of the vibration and noise of a gearbox that considers the flexibility of the shaft is developed. Based on the finite element method (FEM), a coupled dynamic model of a spur gear-shaft-bearing system is established, and the time-varying mesh stiffness (TVMS), the time-varying bearing stiffness (TVBS), and the flexibility of the shaft are considered. The Newmark integration method (NIM) is utilized to obtain the dynamic load of the bearing. Furthermore, the proposed model is validated by experiments. The bearing load is then considered to be the excitation of the housing, and the radiated noise is calculated via the finite element method/boundary element method (FEM/BEM). The effects of the shaft flexibility on the bearing response and radiated noise are discussed based on the proposed method. The results demonstrate that, when the shaft flexibility is considered, the system undergoes the bending vibration of the shaft, and the vibration amplitude and excitation frequency components of the bearing load decrease significantly. Additionally, the main resonance mode of the gearbox is changed, and the radiated noise is enhanced. The effects of the input speed and shaft stiffness on the bearing response and radiated noise are also investigated. The results provide a theoretical basis for the further development of the vibration and noise reduction of gearboxes. INDEX TERMS Finite element method, gearbox, radiated noise, shaft flexibility, vibration response.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.