This paper presents a progressive damage model, which is sufficiently general to predict the ultimate load-bearing ability and complex failure behaviors of the aluminum–carbon fiber/epoxy composite ...vessel structure. The model is implemented in the commercial finite element software ABAQUS based on the integration of material property degradation method (MPDM) and cohesive element (CE) method. The MPDM is implemented by ABAQUS user subroutine UMAT to model the intralaminar failure of composite laminates, while CEs are employed to simulate the delamination initiation and evolution at the interfaces. The progression of damage is controlled by a linear damage evolution law, which is based on the fracture energy dissipating during the process. In addition, the predictions of the model are also compared with experiments and reasonably good agreements are obtained.
High pressure hydrogen storage vessels are the key equipment in hydrogen charge stations. Hydrogen environment embrittlement (HEE) is always the associated problem that is inescapable and difficult ...to be solved completely. In order to decrease the harmfulness of HEE, a unique flat steel ribbon wound pressure vessel (FSRWPV) is designed, whose inner shell material is austenitic stainless steels 0Cr18Ni9 (304) and the steel ribbon material is 16MnR (SA516Gr70). The residual stresses in FSRWPV are analyzed and a stress controlling model is put forward. Through this model, the stress distribution in the FSRWPV wall can be controlled by adjusting the pretension in flat steel ribbons. After optimal designing, the stresses in flat steel ribbon layers are uniform, and that in the inner shell is low or negative. This kind of stress distribution can effectively prevent HEE and stress corrosion cracking (SCC), therefore the FSRWPV has good properties of bearing HEE and SCC. Furthermore, as flat steel ribbon layers are a discrete structure, the online monitoring of FSRWPVs can be conveniently realized, so they have performance of “leak only no bursting”. At the end, an applied example of high pressure hydrogen FSRWPV is given.
•The impact of the preceding layer stacking on rear filament winding is considered.•An improved cubic spline function approach and a novel parabola method were proposed.•The strength analysis of gas ...cylinders based on the parabola method was carried out.•The parabola method adapts well to cylinders with varied sizes and ply schemes.
Due to the characteristics of changing angle and thickness, predicting the outer contour of the vessel dome has been a challenging task in composite pressure vessel design. The impact of preceding layer fiber stacking on subsequent filament winding has never been considered in existing methods of dome thickness calculation. So we developed an improved cubic spline function approach and a novel parabola method that takes preceding layer fiber stacking into account. The example findings show that the improved cubic spline function approach has a weakness in that the selection of several critical parameters is not clearly described and heavily reliant on actual engineering knowledge. The parabola approach described in our study is not only simple in design, but also adapts well to dome contour of gas cylinders with varied sizes and ply schemes. Moreover, the strength analysis of composite gas cylinders was carried out by finite element method. The results show high consistency with hydraulic burst test results, which clearly demonstrates that the parabola method we proposed can effectively realize the precise modeling of composite pressure vessels and will be very beneficial in the design of composite pressure vessels.
This paper presents a multi-scale progressive damage modeling strategy to investigate the damage and failure behaviors of 2D woven composites. The micro-scale and meso-scale RVEs are identified to ...sequentially consider the fiber/matrix scale and the tow architecture scale. The micromechanics failure criterion is then introduced to facilitate analysis of the damage initiation and evolution at the constituent level. An anisotropic damage model is also constructed based on the Murakami-Ohno damage tensor, and the damage evolution is governed by the material fracture energy during failure. The proposed multi-scale strategy is carried out by a user-material subroutine (UMAT) in ABAQUS, which predicts the detailed local responses and complex failure mechanisms of the woven composites. Moreover, experimental tensile and compressive tests are conducted to further validate the proposed model.
A progressive failure analysis algorithm based on micromechanics of failure (MMF) theory and material property degradation method (MPDM) is developed, wherein the MMF is used to predict the failure ...initiation at constituent level and the MPDM is employed to account for the post failure behavior of the damaged materials. The progress of damage is controlled by a linear damage evolution law, which is based on the fracture energy dissipating during the process. This micromechanics-based approach is implemented by a user-material subroutine (UMAT) in ABAQUS, which is sufficiently general to predict the ultimate strength and complex failure behaviors of the composite vessel subject to both high pressure and thermal loading. In addition, the predictions of the model are also compared with those by experiment and traditional finite element analysis.
A life prediction method for the CFRP composite hydrogen storage vessel under cyclic fatigue loading and high temperature conditions was proposed based on the integration of micromechanics of failure ...(MMF) and time-temperature superposition principle (TTSP) method. As a first step, the elastic solution of the cylindrical laminates subjected to internal pressure is obtained based on the classical laminate theory. Then, the MMF is used to calculate the constituent strength from ply strength at various temperatures, and the matrix fatigue master curves are constructed accordingly by using TTSP. Finally, a life prediction procedure using the constituent master curves is described and applied in the MATLAB software to predict the long-term fatigue life of the composite vessel. The reliability of MMF based methodology is also discussed by comparing the predicted results with the experimental ones.
The fast refueling process of hydrogen results in a significant temperature rise within the composite hydrogen storage cylinder, which may decrease the cylinder state of charge and cause complicated ...thermo-mechanical behaviors of the composite structure. This study presents an analytical model, as validated by computational fluid dynamics (CFD) simulations, to study the thermal properties of composite hydrogen storage cylinder during fast filling process. A simple analytical formula for the gas temperature within cylinder and the temperature distribution in solid walls are obtained, which show intuitively the effects of different material and geometry parameters on thermal properties of the cylinder. Furthermore, a 3D finite element analysis (FEA) model, using the analytical results of temperature distribution, is proposed to investigate the coupled thermo-mechanical behaviors of the cylinder. FEA results reflect that the plastic behavior of aluminum liner effectively isolate the thermal stress, and helps to relieve the thermal effects on the whole cylinder in a large extent.
•Theoretical model to study the temperature rise characters of the composite cylinder.•CFD model to predict the thermal behaviors of the 70 MPa fast filling process.•Finite element analysis of the coupled thermo-mechanical properties.•The aluminum liner deforms plastically so as to relieve the thermal stress effectively.
Micro failure analysis of fiber metal laminates Lin, Jiao; Zheng, Chuanxiang; Dai, Yuchen ...
Journal of reinforced plastics and composites,
05/2022, Letnik:
41, Številka:
9-10
Journal Article
Recenzirano
In the failure analysis of composite materials, the damage of fiber and matrix is always noticed rather than the debonding of interface which is responsible for transferring the load between matrix ...and fiber. The stress amplification factors of fiber, matrix, and interface were extracted by establishing representative volume element model with interface and the strength of corresponding constituent is calculated in our work. Micro mechanics of failure served as the initial failure criterion of material components, and user-material subroutine (UMAT) was applied to realize progressive damage analysis of fiber metal laminate (FML) under different loading angles. The analysis results show that it is not strictly correct to directly use the stress on the matrix to calculate interface stress, and the damage trend of interface is consistent with that of fiber. The strain hardening phenomenon of FML decreases with larger loading angle, and the mechanical response of FML is about 45° symmetric due to its structure symmetry. The simulation results are in good agreement with the experiment results.
This study introduces a novel two-stage optimization framework combining deep learning and genetic algorithms for the design of composite grid/skin structures. Firstly, an image dataset of 131,022 ...potential design configurations based on the Double-Double (DD) layup strategy is created. Subsequently, a deep-learning based Auto-encoder model is employed to extract the structural genes from this dataset. These structure genes are then used to establish a surrogate model using transfer learning, which yields accurate predictions of the buckling loads for various grid/skin structures. Finally, the Genetic Algorithm (GA) is employed to explore the optimal design configuration based on the surrogate model, with the objective of maximizing the buckling load while minimizing the weight. Results show that the optimized structure surpasses the traditional Ortho-grid and Iso-grid designs in terms of buckling load by 145 % and 72 %, respectively. Additionally, it improves the structure efficiency by 31 % and 56 %, respectively. These findings emphasize the effectiveness of the two-stage optimization method in addressing complex, multi-objective challenges, offering valuable insights and promising prospects for the optimization design of composite grid/skin structures.
Experimental and numerical studies are carried out to investigate the failure behavior of grid stiffeners under tension and flexural loadings. The grid stiffeners with three different typical layup ...schemes at the intersection were manufactured and tested. A 3D anisotropic damage model based on continuum damage mechanics is developed to modeling the progressive failure behaviors of the grid stiffeners. Besides, the digital image correlation (DIC) technique was adopted to capture the complex deformation and failure process. Results show that introducing discontinuous plies at the intersection could change the failure mechanism and hence improve the mechanical performance of the grid structure. The tensile and flexural strength are improved by 21% and 23% respectively by properly introducing 25% of discontinuous plies at the intersection. This work provides insights on the failure mechanisms of the composite grid stiffeners, and results can be further used towards the optimization design of the grid structure.
•Progressive failure behaviors were captured by 3D anisotropic damage model.•Introducing discontinuous ply at intersection improve the mechanical performance.•Digital image correlation technique was adopted to explore flexural failure modes.
