Papers by Keyword: Progressive Damage

Abstract: The burst strength is the key parameter to the design of glass-fibre reinforced composite (GFRC) pipes with good performance and security. In this paper, the burst strength and the optimized winding angle of the GFRC pipes are derived by the theoretical analysis, experiment and simulation considering the progressive damage. The effects of the winding angle on the burst strength and failure modes are fully discussed. The results show that, the burst strengths obtained by the proposed theoretical formulas and simulation agree well with the experiment results. There is a critical winding angle for the GFRC pipes demarcating the burst modes of axial burst or circular burst. With the increase of the diameter, the critical winding angle decreases, but never less than 55^° . With the increase of the winding angle, the burst strength firstly increases, and then decreases. The winding angle of the GFRC pipes should be optimized between 55^° and 60^° to derive the best burst strength.

Abstract: Over the last few decades research advances provided a couple of different modeling techniques for progressive damage simulation in composite materials. Among them, the eXtended Finite Element Method (XFEM) is a new, but powerful tool for progressive damage simulation. In this work common modeling techniques are reviewed, and then a particular focus is placed on XFEM. The standard implementation of XFEM in Abaqus is reviewed and assessed within an FE simulation of an FRP specimen including manufacturing imperfections. Good agreement is found between simulation results and experimental data. In order to consider the specific damage behavior of the fiber reinforced composite materials within the XFEM frame, an additional implementation of the user subroutine UDMGINI is used, and results are further improved.

Abstract: Spin-blind-riveting (SBR) is a newly developed joining process, which combines the advantages of conventional blind riveting and flow drilling screws. With this technology, it is possible to join two different materials by one-sided accessibility without the need of pre-drilling holes. This complex process cannot be simulated by 2D finite element method. Therefore, a more realistic 3D finite element model for the SBR process is developed using the commercial software package ABAQUS. The applicability of this work is demonstrated for joining magnesium alloy AZ31B and carbon-fibre reinforced plastics. Dynamic effects, thermomechanical coupling, material damage laws, and contact criterion were taken into account in the model. The Johnson–Cook material constitutive equation was used, considering the effects of strain, strain rate, and temperature on material properties. Finally, through simulation, the joint formation, stress distribution and riveting temperature were obtained. Furthermore, a series of experiments were carried out to validate the simulation results. The numerical results are in a good agreement with the experimental results and confirm the promising properties of SBR joints between metal and fibre-reinforced plastics.

Abstract: This paper proposes an efficient analytical failure analysis approach for multilayered composite risers used in the offshore oil industry. This approach is based on a layer-by-layer progressive damage model and a homogenization stress analysis method from which the discontinuous stresses through layers can be efficiently calculated. Different failure theories can be easily integrated into the approach to determine failure initiation in layers with different materials. Progressive failure analysis is based on layer-by-layer material degradation schemes, taking into consideration different failure modes such as yielding, fracture, matrix cracking, fiber broken, etc., in layers with different materials. In this approach, progressive failure information involving failed layers and their failure sequences as well as failure modes can be efficiently predicted for multilayered composite risers under given loading conditions. Failure envelopes of composite risers are generated for either initial failure or ultimate failure in different load spaces, and strengths of composite risers can be predicted under given load ratios. This analytical approach is efficient for failure analysis or strength prediction of composite risers with many layers because stress redistributions in all layers during failure progression can be easily and quickly calculated. A user-friendly interface based on Excel sheets is used to carry out this analytical failure analysis approach. Failure analyses of a 22-layer composite riser under several typical loading conditions are presented to demonstrate the application of the proposed approach. Initial and ultimate failure envelopes of the composite riser are shown in different force spaces. This failure analysis approach provides an efficient way for design of composite risers in the offshore oil and gas industry.

Abstract: The paper deals with progressive and fatigue damage of long fiber E-glass epoxy composite, its residual stiffness degradation and corresponding transverse matrix crack density induced by load-controlled tension. Constant-amplitude fatigue tests in repeated tension of plain [±60]_S; [±30]_S; [0]₈ and [0/90₂/±45/90]_S samples were performed. Sudden onset of transverse matrix cracking and consequent gradual increase of its density has been observed in off-axis plies. The crack density increases with increasing number of cycles or load. Consequently, residual stiffness of the laminate decreases. It has been concluded that progressive/fatigue damage of the laminate is not a continuous homogenous process but the series of discrete sudden events emerging at ply level.

Abstract: A three dimensional analysis model is developed on the fatigue life prediction of composite laminates based on a progressive damage analysis. This model consists of stress analysis, fatigue failure analysis and material property degradation. Teserpe’s failure criteria is used to fatigue damage analysis. Fiber tensile/compressive breakage, matrix tensile/compressive cracking, matrix/fiber shear failure and tension/compression delamination are considered in fatigue damage analysis. The methodologies of sudden degradation and gradual degradation are both applied in the material property degradation. The stiffness and strength gradual degradation is based on the Shokrieh fatigue model, which is based on fatigue test for unidirectional laminates. In order to consider the scatter of the material in the practical structures, the stiffness and strength of the material are randomly distributed using normal distribution in the numerical model. The progressive fatigue damage model is developed in finite element code ABAQUS through user subroutine UMAT, which can simulate the fatigue damage process. Fatigue life of different ply stacking sequences and geometries composite laminates under different cycle loading are predicted. The predicted fatigue life is in good agreement with the experimental results.

Abstract: A progressive damage method of predicting the fatigue life of mechanically fastened joints in fiber-reinforced plastics was established, which is integrated fatigue material property degradation models. The equations of virtual work based on the theory of time increment were deduced to analyze stress-strain states under fatigue loading conditions. The three-dimensional Hashin-type fatigue failure criteria were introduced into the method to detect damage for diverse damage modes. The criteria of the structure catastrophe and the sudden material property degradation rules including the correlation among four basic damage mechanisms were also established. A software module of progressive damage analyses for bolted composite laminates is compiled, which is convenient for the application in engineering. The fatigue life, failure initiation, propagation and catastrophic failure of composite bolted joints under tension-tension fatigue loading conditions are predicted by using the fatigue progressive damage method established in the paper. An excellent agreement is found between data obtained from this study and the experiment.

Abstract: The paper presents the numerical studies of two different tubes under axial impact loading structures. The cylindrical tubes filled with closed-cell polymeric foam. The deformation and failure mechanism of this new structure were observed and analyzed numerically using the finite element method. It is revealed that the stress distribution and fracture of the foam-filled tube structure are different from those of foam-filled tube. In comparison with double cell foam-filled tubes, the load-carrying capacity of this new structure is much steadier, the collapse behavior resistance is enhanced, and the weight efficiency of energy absorption is higher. Parameters affecting the performance of the foam-filled tube structures are also studied. Comparison were carried out with load versus displacement curve and also dynamic mean load as well as dynamic absorbed energy versus deformation of tubular collapse modeling failure mode using finite element analysis.

Abstract: Aimed at the lack of research about damage mechanism, a 3-D progressive impact damage analysis method was applied to analyze the low-energy impact damage process of T300/BMP-316 laminates with three different ply stacking sequences. The influences of ply parameters on the impact damage of laminates were researched. The impact damage mechanism was analyzed combined with the figure of impact stress in laminates. It is showed that the matrix cracking is caused by the inconsistent distortion of the matrix and fiber when the tensile stress that perpendicular to the fiber direction reaches a given value, and the delamination near to the impacted back face and front face are caused individually by the matrix cracking and the inconsistent bend stiffness between two laminas.

Abstract: 2.5D woven composites has been used broadly. But its failure reason and process has not been researched clearly. To describe whole the tensile process in weft direction exactly, Based on the yield criteria ,yield criteria and elastic mould reduced rule are consummated to analyze the process of yield process; Meantime, Hoffman failure criteria is used to analyze the broken process and the corresponding elastic mould reduced rules is given. FEA method is adopted to simulate and analyze the whole tensile process of 2.5D woven composites in weft load at last. To verify the failure criteria and the corresponding elastic mould reduced rule, weft –tensile tests of six kind of 2.5D composites have been done. Results of contrast show that failure criteria and the corresponding elastic mould reduced rule is very suit for 2.5D woven composites. The whole failure progress for a sample with hole are simulated at the end of this paper.