Progressive Failure Analysis Method Research Articles

Multi-scale analysis of ultimate bearing capacity in composite hull joints: failure mechanism and numerical simulation

ABSTRACT Progressive failure analysis method is the main method to analyse the ultimate bearing capacity and failure mode of composite structures. Multi-scale method can effectively reduce the dependence of damage mode and stiffness degradation analysis on material parameters. Based on the multi-scale method, from micro-scale to mesoscale and then to macro-scale, the equivalent modulus and equivalent strength of fibre bundles, single-layer laminates and multi-directional laminates were predicted respectively, and the prediction method of ultimate bearing capacity of large-scale composite structures from material level to structure level was constructed. The mechanical properties of standard composite materials and the ultimate bearing capacity of full-scale composite joints were tested respectively, and the ultimate bearing capacity and failure mode of L-joints were predicted by numerical method. The results show that the numerical simulation method based on multi-scale can accurately predict the ultimate bearing capacity and failure mode of large-scale joints of the hull.

Determination and Verification of Repair Tolerance of Patch Repaired T700SC/EC240A Composite Laminates Based on Progressive Failure Analysis Method

Determination and Verification of Repair Tolerance of Patch Repaired T700SC/EC240A Composite Laminates Based on Progressive Failure Analysis Method

Thermal-fluid-structure coupling progressive failure analysis for the type III composite cylinder under localized fire

Predicting the failure characteristics of composite cylinders under fire is the key to improve the fire resistance and safety of cylinders. However, the current thermal-mechanical coupled failure analysis methods for composite cylinders under fire have several limitations such as oversimplification of the cylinder dome's geometric model and the fire source. To solve these problems, a comprehensive three-dimensional thermal-fluid-structure coupling progressive failure analysis method is developed. This method encompasses a fully coupled conjugate heat transfer model, a FLUENT-ABAQUS data transfer method, and a progressive failure analysis model integrates the Hashin failure criterion and nonlinear damage evolution for fiber reinforced composites. The method is adopted to analyze the fire-resistant performance of a type Ⅲ cylinder to obtain the fire-resistant time, failure pressure and burst location of the cylinder, finding that the pattern of failure pressure depreciation correlates with the burst location of cylinder under localized fire. Besides, the influence of the glass-fiber/epoxy layer on the fire-resistant performance of the cylinder is discussed, demonstrating that even a thin layer of glass-fiber epoxy can significantly increase the fire resistance time of the cylinder.

A Multi-Scenario analysis method for collapse risks due to initial local failure of building structures

Traditional progressive failure analysis is usually computationally expensive and can only be used to analyze a limited number of cases. The resulting mechanical data on structural components are not suitable for displaying collapses or providing an intuitive reference for emergency management. In addition, numerical models do not incorporate uncertain factors in failure development, which makes it difficult to deduce multiple scenarios of future. This paper proposes a multi-scenario progressive failure analysis method based on a sub-region model for emergency management. Firstly, the material model is augmented with a possibility factor to evaluate the failure of components based on internal forces, and thereby deduce different progressive collapse scenarios. Secondly, the building structure is divided into several sub-regions based on the damage correlation of components, so that the degree of regional collapse can be demonstrated at a more macroscopic scale, which is more suitable for emergency management. By analyzing typical failure scenarios, the collapse evolution rules at the sub-region level can be summarized, which can be used for deducing the results of multiple collapse scenarios rapidly. The proposed method can identify the weak positions of buildings, deduce highly probable progressive damage scenarios, and exhibit macro collapse processes. The multi-scenario analysis results can serve as a reference for collapse safety management in risk pre-assessment and help to reconstruct the collapse process in post-disaster analysis.

Force and energy equilibrium-based analytical method for progressive failure analysis of translational rockslides: formulation and comparative study

Force and energy equilibrium-based analytical method for progressive failure analysis of translational rockslides: formulation and comparative study

A non-linear Ritz method for progressive failure analysis of variable angle tow composite laminates

A Ritz formulation for non-linear analysis of damage initiation and evolution in variable angle tow composite plates under progressive loading is presented. The model is built on a few key items. It assumes first order shear deformation theory kinematics and non-liner strains in the von Kármán sense. The constitutive relationships are formulated in the framework of continuum damage mechanics at the ply level, so that each laminate layer can experience in-plane damage initiation and evolution, then reflected in material softening and loss of local stiffness. A Ritz polynomial expansion of the primary variables and the minimization of the total potential energy provide the discrete solution equations, which are then solved with an incremental-iterative approach for capturing damage evolution. A few tests have been successfully performed to validate the approach. Eventually, some original results about variable angle tow plates under progressive in-plane compression loads highlight the effect of damage on the post-buckling response.

A novel post-processing method for progressive failure analysis of brittle composite compression

Finite element analysis of brittle materials in axial compression typically uses element deletion to allow continued global deformation post-element-failure. However, element deletion produces cyclic load-displacement curves that underestimate energy absorption and are not representative of a continuum system. Two key observations support the conclusion that results from an appropriately discretized model can be an adequate representation of a continuum system. Specifically, the frequency of the oscillations in the load-displacement curve is directly dependent upon element length in the loading direction, and the peak amplitudes of oscillations are mesh size independent. A method of post-processing the analysis results, by connecting the peak amplitudes of oscillations, is proposed and applied to a series of continuous carbon fiber composite crush tubes. The load-displacement curve, stable crushing load, and specific energy absorption of the post-processed results compare well to an experimental study of crush tubes with similar layups.

Progressive damage analysis for multiscale modelling of composite pressure vessels based on Puck failure criterion

This study proposed a method for progressive failure analysis to investigate the failure modes of 35 MPa Type III composite pressure vessels during hydraulic burst tests. Representative volume elements (RVEs) were introduced, and the degraded elastic parameters of composite, which include fibre and matrix failure modes, were calculated by the finite element analysis (FEA) method to obtain the macroscopic stiffness degradation parameters. The Puck failure criterion was adopted, and the effective elastic parameters calculated from RVEs was introduced by the UDSLFD subroutine to simulate the multiscale progressive damage of composite layers during hydraulic burst test. Combined with acoustic emission detection, composite microscopic photos and hydraulic burst test, the burst pressure and failure modes of the vessels were analysed. The results showed that meso-macroscopic finite element models could effectively predict the progressive damage of composite pressure vessel, such as matrix crack, interlaminar failure and fiber fracture under internal pressure loading. Finally, the predicted burst pressure was about 5.4% average difference of the actual experimental results. Besides, cylinder section of the vessels was the predicted blasting position, which was close to the actual tests. Thus, the proposed method can provide theoretical reference for the design and optimisation of composite pressure vessels.

Development and Evaluation of Crack Band Model Implemented Progressive Failure Analysis Method for Notched Composite Laminate

Progressive failure analysis (PFA) is widely used to predict the failure behavior of composite materials. As a structure becomes more complex with discontinuities, prediction of failure becomes more difficult and mesh dependence must be taken into account. In this study, a PFA model was developed using the Hashin failure criterion and crack band model. The failure initiation was evaluated using the Hashin failure criterion. If failure initiation occurred, the damage variables at each failure mode (fiber tension and compression; matrix tension and compression) were calculated according to linear softening degradation and they were then used to derive the damaged stiffness matrix. This matrix reflected a degraded material, and PFA was continued until the damage variables became “1,” implying complete material failure. A series of processes were performed using the finite element method program ABAQUS with a user-defined material subroutine. To evaluate the proposed PFA model, experimental results of open-hole composite laminate tests were compared with the obtained numerical results. The strain behaviors were compared using a digital image correlation system. The obtained numerical results were in good agreement with the experimental ones.

A new analytical method for progressive failure analysis of two-dimensional triaxially braided composites

A new analytical model is developed for predicting progressive damage, equivalent stiffness and strength of a two-dimensional triaxially braided composite (2DTBC) under tensile and compressive loading. In this model, an alternative concept of equivalent lamina elements (ELEs) is first established for the four subcells parallel to the axial direction in a representative unit cell of the 2DTBC; Next, the ELEs are laminated in the thickness direction and integrated via a series-parallel model to establish a two-way stress–strain response within the unit cell, that allows failure initiation and propagation in the ELEs to be examined and ultimate failure strength to be predicted. The analytical results are validated against a finite element simulation of an infinite plate as well as experimental results. Numerical case studies are conducted to assess the sensitivity of analytical results against compressive strength of ELEs. The results demonstrate the capability and efficiency of the present model for predicting the mechanical responses of single-layer and multi-layer 2DTBC specimens under different loading conditions.

The effect of tear straps on compressive carrying capacity of composite omega single-stringers

In this paper, the progressive failure analysis method is used to analyze suppression effect and mechanism of tear straps, and study the effect of tear straps with varying coverage on compressive carrying capacity of composite omega single-stringers. Based on ABAQUS, several omega single-stringers with common, half-inclusive and all-inclusive configuration are established. Buckling and post-bucking processes of single-stringers subjected to axial compressive load are analyzed. Hashin failure criterion and Camanho model are adopted, respectively, as the failure criterion and degradation model of materials. Cohesive model is used to simulate the bonding interface. The results show that by strengthening the local stiffness of the stringer and skin, tear straps resist the local buckling deformation and control the occurrence and range of damage induced by local buckling, hence preventing the reduction of the carrying capacity. The all-inclusive configuration is more effective than half-inclusive. The conclusions obtained show that tear straps can improve overall stiffness and load-carrying capacity and the all-inclusive configuration has a higher effect than the half-inclusive configuration. Tear straps play a vital role in improving the carrying capacity of structures.

A mechanically fastened composite laminate joint and progressive failure analysis

A comprehensive procedure for a mechanically fastened composite laminate joint (ASTM D5961 Proc. A, B) is demonstrated from fixture design to analysis of test results. The ASTM tests are applied to evaluate the standard laminate properties and the composite joints. Composite laminate mechanical joints were analyzed using the finite element method (FEM), and the results were compared to test results. A progressive failure analysis (PFA) was applied to the FEM to predict the overall failure behavior of the test specimens. Three laminate failure theories – maximum stress, maximum strain, and Tsai–Wu – were applied to the PFA to predict the test failure load, displacement and strength. The PFA method was suitable to predict the initial test range of test and maximum test load except for the excessive failure area.

Failure analysis of C/SiC composites plate with a hole by the PFA and DIC method

The progressive failure analysis (PFA) and digital image correlation (DIC) method were used to study the strain distribution and failure evolution of C/SiC composites with a circular hole under tension. The nonlinear constitutive relation based continuous degradation strategy (NCRCDS) was combined with the PFA and compared with the sudden material property degradation strategy (SMPDS). The maximum strain criterion was adopted in the PFA to model local failure. The initiation and evolution of local failure around the hole were studied by PFA and DIC method. The results indicate that the local failure distribution simulated by PFA was close to that of the DIC measurement. The strain field was relevant to the surface topography and the microstructure of the material, and the strain distribution around the hole was affected by the arrangement and the damage of the fiber bundle. The simulated results of the strain distribution were in good agreement with the DIC measurements.

Experimental study and progressive failure analysis of stitched foam‐core sandwich composites subjected to low‐velocity impact

The effects of the impact energy and stitch density on low‐velocity impact (LVI) damage in sandwich structures composed of a stitched foam core and woven face sheets have been investigated both experimentally and numerically. In the LVI experiment, force–time curves are recorded and analyzed to study the impact response of stitched foam core sandwich structures. In the numerical investigation, a progressive damage model for the composite structures is developed based on the continuum damage mechanics (CDM) approach in which the damage forms of the composites are predicted by the strain‐based Hashin criteria. The damage evolution is simulated by the stiffness degradation procedure in exponential form. Interface elements are established between the panels and foam core to simulate the initiation and propagation of inter‐laminar damage. The stitching region is simplified as glass fiber reinforced resin columns, and its mechanical parameters are estimated by a mixed series‐parallel model. The numerical and experimental results are in good agreement, which demonstrates the validity of the progressive failure analysis method. The energy absorption is discussed using a numerical method, and the results help to characterize the damage mechanisms of LVI on stitch foam‐core sandwich composites. POLYM. COMPOS., 39:624–635, 2018. © 2016 Society of Plastics Engineers

Reliability analysis of ultimate compressive strength for stiffened composite panels

The prediction and reliability evaluation of ultimate compressive strength of stiffened composite panels are both essential for safe structural design. In this paper, the progressive failure analysis method is utilized to predict ultimate compressive strength of stiffened composite panels by using ABAQUS. Since a large number of ultimate compressive strength must be analyzed in the process of reliability evaluation by using standard reliability methods, the relationship between the buckling load and the ultimate compressive strength is used to establish a new limit state function to reduce the computational efforts. Only one time the ultimate compressive strength is analyzed in the process of reliability evaluation by using the proposed method. The results of numerical examples show that (a) the relative errors between the ultimate compressive strength obtained by using the proposed method and the experimental data are 2.53% and 1.68% for samples A and B, respectively; (b) the reliability results obtained by using the proposed method are very close to the ones obtained by using the classical method, and the ratios of the proposed method to the classical method are only 1.18% and 1.66% for samples A and B in terms of the total computational time.

Stress AnalysisandFailure Predictionof Adhesively BondedSingle-lapLaminates Joints Subjected to the Tensile Loading

On the basis of the existing experimental results and considering five kinds of failure modes, failure prediction of adhesively bonded single-lap laminates joints with adherend thickness 3mm, adherend thickness 2mm and defect in the adhesive layer under uniaxial tensile loading is performed by progressive failure analysis method. The numerical analysis of composites adhesive joints is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The error of computaional and experimental failure loads is 3.0%. Evolution of adhesive progressive damage is simulated effectively and the initial position and reason of damage is discovered. Furthermore, a finite element simulation is carried out to analyze the stress distributions in the mid-surface of the adhesive layer and the bonding interface. It is found that stress concentration is all emerged near by 1.25mm on the overlap zone ends, that is the initial point of damage, and it is the main factor that the joint strength is affected by peel/shear stress concentrations at overlap zone ends. The computational results are in good agreement with the experimental values.

Progressive Failure Analysis of Adhesively Bonded Laminates Joints with Spew Fillets

Failure prediction of adhesively bonded single-lap laminates joints with spew fillets in the overlap ends under uniaxial tensile loading is performed by progressive failure analysis method. A modified form of Hashins failure criterion by Shokrieh and maximum stress criterion are used to detect the laminate failure and adhesive failure, respectively, where a sudden degradation model is proposed to reduce engineering material constants. Five kinds of failure modes are considered. The numerical analysis of composites adhesive joints is implemented in ANSYS Parametric Design Language (APDL) with commercial finite element codes ANSYS. The error of simulation and experimental failure loads is 6.9% and the model has been validated by comparing numerical results with experimental results.

Progressive failure analysis of slope with strain-softening behaviour based on strength reduction method

Based on the strength reduction method and strain-softening model, a method for progressive failure analysis of strain-softening slopes was presented in this paper. The mutation is more pronounced in strain-softening analysis, and the mutation of displacement at slope crest was taken as critical failure criterion. An engineering example was provided to demonstrate the validity of the present method. This method was applied to a cut slope in an industry site. The results are as follows: (1) The factor of safety and the critical slip surface obtained by the present method are between those by peak and residual strength. The analysis with peak strength would lead to non-conservative results, but that with residual strength tends to be overly conservative. (2) The thickness of the shear zone considering strain-softening behaviour is narrower than that with non-softening analysis. (3) The failure of slope is the process of the initiation, propagation and connection of potential failure surface. The strength parameters are mobilized to a non-uniform degree while progressive failure occurs in the slope. (4) The factor of safety increases with the increase of residual shear strain threshold and elastic modulus. The failure mode of slope changes from shallow slip to deep slip. Poisson’s ratio and dilation angle have little effect on the results.

Tensile Failure Strength Analysis and Experimental Confirmation of Stitch Reinforced Composite of T-stiffened Structure

Based on the progressive failure analysis method, taking account of 7 kinds of failure modes: stitch thread failure mode, resin extend (or compress) failure mode, fibre extend (or compress) failure mode, extend (or compress) delamination failure mode, a new failure analysis FE model was proposed for predicting the tensile strength of stitch-reinforced composite T-stiffened structures. The 3D solid element and truss element were used to simulate laminate and stitch thread individually in the FE model. The Hashin failure criterion and stiffness degradation technology are used to analyze damage failure of the stitch T-stiffened structure. Comparing the initial and final damage failure strength with those of experiments on stitch composite T-stiffened structures validated the Python secondary development program for the FE model presented in the paper. There was good agreement between the failure strength from the damage failure analysis and that of the experiment. This indicated that the model was correct, and that it could be a reference for stitch-reinforced composite design and analysis.

Failure Prediction of Laminated Composites with the Hole under in-Plane Compressive Loading

Failure process of laminated composites with the hole under in-plane compressive loading is performed by progressive failure analysis method. A modified form of Hashin’s failure criterion by Shokrieh is used to investigate the failure, where a sudden degradation model is proposed to reduce engineering material constants. The numerical study of laminated composites is implemented in ANSYS Parametric Design Language (APDL). The initiation and propagation of local damage and response of laminated composite structures from initial loading and ultimate failure are predicted. The model has been validated by comparing numerical results with existing experimental results. And then failure analysis of specimen fabricated from M40J/Ag80 on influence of the hole under compressive loading has been performed by the proposed model.