Material Failure Criteria Research Articles

Fatigue failure criterion of materials with static constitutive curve as the limit value

The fatigue failure problem actually can be explained by fatigue stress–strain envelope, and the fatigue evaluation based on fatigue stress–strain can avoid the uncertainty of selecting fatigue criteria in engineering applications. However, the application of experimental fatigue envelope criterion based on stress–strain curve is limited to concrete and rocks, and it also can not predict the fatigue failure time. To further develop the availability of fatigue stress–strain envelope criterion, the fatigue failure criterion of materials with static constitutive curve as the limit value is proposed to describe high-cycle and low-cycle fatigue failure through theoretical deduction of classic fatigue criteria and analysis of experimental results. The proposed criterion reveals the constraints mechanism that the fatigue life is dominated by fatigue failure stress–strain in the fatigue envelope surface. Finally, the comparison between calculated and experimental fatigue life indicates that the proposed criterion is suitable to.describe the fatigue failure well and has the comprehensive application prospect.

Numerical Study on Ductile Failure Behaviours of Steel Structures under Quasi-Static Punch Loading

A reliable finite element procedure to simulate shear-dominated ductile fractures in large-scale, thin-walled steel structures is still evolving primarily due to the challenges in determining the failure criterion of metal materials under complex stress states. This paper aims to examine the accuracy of the modified Gurson–Tvergaard–Needleman (GTN) model considering the shear failure in simulating the ductile fracture of steel plate structures under quasi-static punch loading. The modified GTN damage models are performed by the ABAQUS user-defined material subroutine (VUMAT). The void-related parameters and shear damage parameters of Xue’s and the N-H modified GTN models are calibrated from test specimens with various geometries corresponding to different stress triaxiality and shearing conditions. The damage evolution associated with shearing of voids in the modified GTN models has strong influences on the stress triaxiality versus plastic strain under complex stress states, especially for the shear-dominated loading conditions. Based on the original GTN model, Xue’s and the N-H modified GTN model with calibrated material parameters, a numerical comparative study examines the ductile fracture of steel non-stiffened plates and stiffened plates under punch loading. Benchmarked against the experimental studies, the numerical simulations demonstrate that the shear-driven void evolution in the modified GTN model imposes significant effects on the load–displacement responses as well as the onset and extension of ductile fractures in steel plates under punch actions. The N-H modified model with calibrated shear damage parameters shows a better correlation with the ductile fractures in steel plates observed in the experiment than the original GTN model and Xue’s modified GTN model. As a result of this study, the modified GTN model considering shear action can be applied for practical applications in the crashworthiness assessment of ship collision and grounding.

FEA-Dominant Reliability and Lifetime Model of Double-Sided Cooling SiC Power Module

Owing to the low parasitic inductance, high power density, and excellent heat extraction performance, double-sided cooling (DSC) is regarded as a promising packaging solution for the silicon carbide (SiC) power module. Nevertheless, given the unclear failure mechanism and missed lifetime model, the reliability assessment and lifetime prediction of the DSC SiC power module remains a concern. Besides, the accelerated aging test generally used for the reliability assessment of the SiC power module is extremely time-consuming and costly. Therefore, the obstacles mentioned before limit the development and deployment of the DSC SiC power module. Aiming to fulfill these research gaps, based on the aging mechanism and failure criterion of packaging materials, the lifetime model of the DSC SiC power module is proposed in this paper. Comparative experiments show that the relative error of the FEA-dominated model is less than 6%. Moreover, the stress property and creep principle of the solder layer in SiC and Si power modules are assessed, respectively. Besides, the lifetime models of SiC and Si power modules applying different packaging materials are created. It is found that the lifetime of the DSC power module is twice that of the single-sided cooling (SSC) counterpart. Furthermore, applying the same packaging, the lifetime of the SiC power module decreases by 70% compared with the Si counterpart. In addition, the lifetime of the DSC SiC power module affected by different materials such as ceramic and spacer is studied in order to enhance its reliability.

Experimental and numerical response and failure of laterally impacted carbon/glass fibre-reinforced hybrid composite laminates

The paper presents low-velocity impact tests and finite element simulations of carbon/glass fibre-reinforced hybrid composite laminates struck by a pyramidal frustum impactor in order to examine crushing deformations and failure mechanisms. Three mass ratios between the carbon and glass fibre (1:2, 1:1 and 2:1) are considered to compare the influence of the fibre hybridisation on the impact resistance of these laminates. This investigation is an essential step in the design process when ship structural crashworthiness is considered. The experimental results are presented in terms of the force-displacement responses and permanent deformations. Aspects of particular relevance to the deformation and fracture behaviour of hybrid-composite structures subjected to accidental loads are discussed, especially fibre/matrix debonding and fibre damage. Glass fibre shows better impact resistance than carbon fibre, despite the higher modulus of the latter. A series of simulations performed by the LS-DYNA finite element solver are used to calibrate the material failure criteria based on the experimental data, and the sensitivity of the failure criteria to mesh sizes is investigated.

Numerical simulation and analysis of the chain-reaction implosions of multi-spherical hollow ceramic pressure hulls in deep-sea environment

Thin-walled hollow ceramic pressure hulls on deep-sea underwater vehicles are at risk for highly destructive chain-reaction implosions. A numerical method of simulating the chain-reaction implosions of multiple ceramic pressure hulls in deep-sea environment was developed. The fluid solver used for this method adopted the compressible multiphase flow model and adaptive mesh refinement, combining the finite element method and the failure criteria of brittle materials to determine the conditions that trigger an implosion. An implosion experiment was conducted for a single ceramic pressure hull, and the experimental results verified the accuracy of the fluid solver based on compressible multiphase flow theory. The chain-reaction implosions of two ceramic pressure hulls were also computed. The computation results showed that the air cavity in a spherical pressure hull diffused the expansion wave during the compression stage. The pressure drop in the flow field initiated by the expansion wave caused the ceramic spherical shell to reach its ultimate strength, thus triggering chain-reaction implosions. The two implosion shockwaves were superimposed during the diffusion process. The peak pressure at the superposition position of the two shockwaves is related to the spacing between the two pressure hulls.

Damage evolution and full-field 3D strain distribution in passively confined concrete

The damage evolution of concrete under multiple stress states is complicated because the triaxial stress on the heterogeneous concrete affects mesoscale interactions between aggregates and mortar, which further alters the internal cracking of concrete and its load bearing mechanism. Hence, probing the internal cracking evolution of concrete under a complex stress state is the key to better understanding the characteristics and failure mechanism of concrete material. This study conducted a series of X-ray computed tomography (X-CT) tests on fiber-reinforced polymer (FRP) confined concrete with varied in situ axial load levels. Different cross-sections of concrete specimens—circular, square with round corners, and square with sharp corners—were designed to achieve uniform or nonuniform passive confinement conditions. The obtained volumetric images from X-CT clearly exhibited the internal damage evolution of concrete, where crack growth, shear banding, and failure localization were displayed for the concrete under varying triaxial stress states. The development of damage to concrete due to cracking with increasing load was also quantified by image segmentation. In addition, the digital volumetric correlation technique (DVC) was employed to produce the volumetric displacement field and strain distribution in the confined concrete according to the image variation of natural speckles. A three-dimensional internal strain analysis revealed that strain localization was mainly caused by mesoscale concrete heterogeneity and nonuniform confinement. More importantly, this study provides the first database of full-field strain tensors for FRP-confined concrete under different axial load levels. These data are valuable for the development of concrete mechanics, failure criteria of materials, and computational modeling of concrete materials and their structures, especially for concrete under complex stress states.

Failure Strength of Automotive Steering Knuckle Made of Metal Matrix Composite

This article presents the static performance of composite steering knuckle due to drive on an equivalent road, including different types of roughness and maneuvers. To achieve this purpose, the driving of a full-vehicle model was simulated using the multi-body dynamics (MBD) method, and the imposed loads on connection points of the steering knuckle to different components of the suspension system were extracted considering various maneuvers. Next, CATIA software was used to prepare a smooth model of the steering knuckle by employing coordinate measuring machine (CMM) data. Stress analysis was performed under the maximum value of the loading history in finite element (FE) software. Eventually, the safety factor was calculated based on some well-known criteria for static failure of the composite materials. Moreover, the optimum value of tungsten carbide as a reinforcing substance in aluminum composite was estimated to increase failure strength. The results show that an increase in tungsten carbide leads to an increase in the strength of the steering knuckle under purely axial loads (normal stress criterion) and also that an increase in this substance leads to a decrease in the strength of the part under shear loads (shear stress criterion). Therefore, based on the nature of the loads (i.e., multi-axial non-proportional random amplitude loading conditions) applied to the automotive steering knuckle due to actual conditions, this metal matrix composite (aluminum matrix and tungsten carbide as reinforcement) is not practical.

Confinement-dependent failure criterion for high-strength concrete in multiaxial stress states

High-strength concrete is becoming progressively wide applications in modern civil engineering structures because of its excellent mechanical properties and workability. However, most of the commonly adopted failure criteria were developed based on the low-strength concrete (cylinder compressive strength less than 40 MPa), and they may not accurately reflect the behavior of high-strength concrete due to the changes in its failure modes from intergranular failure to transgranular failure. The systematic analysis of databases consisting of 2120 experimental results of concrete multiaxial test collected from a wide range of existing literature has been carried out. It was found that the ratios of concrete ultimate strengths under uniaxial tension and equibiaxial compression to its uniaxial compressive strength (fc0) were negatively correlated with the uniaxial compressive strength. While under triaxial compression, the ultimate strength enhancement was affected by the uniaxial compressive strength and the degree of confinement (σm/fc0) simultaneously. On this basis, through the careful discussion of the morphological characteristics of concrete cracks after multiaxial failure, the concepts of the weakly and heavily confined states of concrete under triaxial compression were developed quantitatively, and the critical degree of confinement σm/fc0 = −0.8 was proposed. Under the heavily confined state, the ultimate strength enhancement of the high-strength concrete was less than that of the low-strength concrete, whereas there was no difference between them under the weakly confined state. A confinement-dependent failure criterion was formulated that utilized the piecewise compressive meridian to achieve a more rational description of the multiaxial ultimate strength for high-strength concrete. With the suggested failure criterion, a peak axial stress model for confined concrete was proposed. As verified by the experimental data of concrete confined by fiber-reinforced polymer (FRP) wraps from existing literature, which contains both high-strength and low-strength concrete, the proposed model showed better prediction accuracies with less scatters than the existing counterparts. This study can also be a reference for the research of the multiaxial failure criterion of other concrete-type materials.

An efficient micromechanics-based finite element model for failure analysis of laminated composites

Accurately predicting ultimate strength of composite laminate is still a great challenge, especially only based on the constituent properties. In this paper, the micromechanics Bridging Model and systematic failure criteria for the constituent materials with emphasis on matrix failures subjected to three dimensional (3D) loads are compiled into a UMAT subroutine for ABAQUS to analyze failures of a laminated composite structure. The main purpose of this research is to greatly reduce calculation costs for loading conditions of in-plane tension or compression by introducing a simplified 3D finite element model based on the Pipes-Pagano theory. In all calculation cases, only the constituent properties together with the transverse tensile strength of unidirectional composite are needed as input data. Later in this paper, sufficient illustrations of 81 different composite laminates composed of 14 material systems are analyzed to confirm the practicability of this model.

Numerical analysis of tensile failure of bolted composite laminates

PurposeThe influence of the number and arrangement of bolts on the tensile properties of bolted composite laminates was studied in the present study.Design/methodology/approachBased on the finite element model, the stiffness degradation method is used to simulate the damage evolution process for the failure of bolted composite laminates. Using ABAQUS finite element software combined with material failure criteria, the numerical calculation of the connection strength and failure mode of bolted composite laminates was carried out.FindingsThe results of the study show that the tensile strength of the composite laminates connected by three bolts is higher than that of the laminates connected by two bolts. And the arrangement of different bolts has a great influence on the failure strength of bolted laminates.Originality/valueBolted connection of composite laminates is a common problem in engineering practice. The effect of bolt arrangement and number on the strength of composite laminates is studied in this manuscript.

Dynamic response and safety assessment of inner‐wall corroded concrete pipeline in service subjected to blasting vibration

AbstractBuried pipelines in urban area are prone to corrosion defects for many years. Ensure the safety of buried corrosion pipelines is a key concern during tunnel blasting excavation. Based on the blasting engineering along Shenzhen Metro Line 12, the field test of full‐scale concrete pipeline adjacent blasting was implemented. The dynamic response of concrete pipeline induced by blasting vibration was analyzed by using the dynamic finite element numerical simulation method, and the reliability of numerical simulation was verified by the field monitoring data. On this basis, considering the corrosion defect morphology of pipeline, the distribution characteristics of peak particle velocity and peak effective stress of concrete pipeline with different corrosion depths, corrosion widths, and corrosion lengths induced by blasting vibration were discussed. The parameter analysis method was used to research the influence of corrosion morphology parameters on the dynamic response of the pipeline, and the corrosion depth of the inner‐wall of the pipeline was defined as the main control parameter of the dynamic response. According to the failure criteria of concrete materials, the safety criterion of corroded concrete pipelines with different service years subjected to blasting vibration was established.

Material failure criterion in the finite element analysis of aluminium alloy plates under low-velocity impact

A material failure criterion, based on the combination of the revised Bressan-Williams-Hill (BWH) local instability criterion and damage evolution model, is presented to analyse numerically the fracture behaviour of aluminium alloy plates struck by an indenter with various nose shapes. The parameters used in the material failure criterion are easily calibrated for coarsely meshed shell structures. The failure modes of aluminium alloy plates under spherical, ellipsoidal, cylindrical and cuboidal indenters are discussed. The discrepancy between tensile and shear failures is considered in the failure criterion. The failure criterion is implemented into the finite element code LS-DYNA and verified against a series of experimental results. The revised material failure criterion can reasonably predict the onset of fracture of aluminium alloy plates with low mesh dependency.

Concept of Equivalent Stress Criterion For Predicting Failure of Brittle Materials

Purpose: A paucity of proven failure criteria for brittle engineering materials exists, and this paper intends to present and validate a novel concept of equivalent stress criterion for predicting the failure of brittle isotropic homogeneous materials based on the concept of effective causative failure stress.
 Design/Methodology/Approach: Mathematical modelling is first performed based on strain-state equivalence, followed by conversion to the equivalent causative stress. The model is then validated with experimental and other data and with comparisons to traditional models. The material studied is BS 1452 Grade 250 continuous-cast grey cast iron with a Young’s Modulus of 39 000 MPa and ultimate tensile strength of 290 MPa. The test samples were prepared square in shape 12 mm x 12 mm to enable stresses in two perpendicular directions. Data is generated from uniaxial and bi-axial tests, performed using a standard universal testing machine, INSTRON 880, improvised to enable bi-axial recordings.
 Findings: Results point consistently to higher fidelity and transparency of the new model in representing the state of stress, especially in the second and fourth quadrants of the principal stress diagram, where Rankine’s criterion completely ignores stress differences and Mohr handles shear stresses in a suboptimal fashion. Both the maximum principal stresses and maximum shear stresses predicted by the proposed model are found to be somewhat greater than those from the traditional models, indicating higher accuracy and greater aggressiveness in prediction. The findings have further revealed that shearing effects play a greater role in the failure of engineering brittle materials than traditional failure theories have considered.
 Research Limitation: The study involved improvisation to enable biaxial stress recordings. This process was not perfect, resulting in smaller-than-ideal values of the lateral stresses.
 Practical implication: The study recommended process and equipment development toward perfecting multiaxial tests.
 Social implication: The survey will enrich the literature with pertinent design methodology to help in product design, including social-interest products. 
 Originality / Value: Since truly homogeneous materials are known to withstand very high hydrostatic pressures, direct stresses alone do not constitute valid failure criteria for all loading conditions.

Effect of material failure criteria on collision behavior of metro vehicle end structures

This study comprehensively analyzes the failure behavior of metro vehicle end structures (VESs) during collisions, using the common material SUS301L-MT in a stainless steel metro and its VES as the research object. First, constitutive and failure tests are performed on the material, the macro–micro characterization of its mechanical properties is performed, and the failure strains and morphologies under various stress states are obtained and discussed. Subsequently, two failure criteria, Von Mises (VM) and Generalized Incremental Stress State Dependent Damage Model (GISSMO), are calibrated and established. Finally, the crashworthiness evaluation indexes of the VES are defined, and vertical offset collisions of metro VESs for different speed levels are numerically analyzed. The results show that the stress triaxiality significantly affects the failure strain of stainless steel SUS301L-MT, with the maximal difference for different stress states reaching 51.10%. SUS301L-MT stainless steel exhibits strain-rate strengthening and yield hysteresis effects. Overall, the numerical results for the VM criterion are worse than for the GISSMO criterion, which more accurately describes the collision behavior of metro VESs under complex stress states.

Quantifying Alignment Deviations for the In-Plane Biaxial Test System via a Shape-Optimised Cruciform Specimen.

The loading coaxiality of an in-plane biaxial test system and the structure of a cruciform specimen markedly affect the test results. However, due to the lack of methods for correcting the loading coaxiality and designing the cruciform specimen, the data scatter of the test results of the in-plane biaxial test systems varies from the laboratory to different tests. To quantify the loading coaxiality of the in-plane biaxial test system, we first developed a model to calculate alignment deviations with strain distribution of the shape-optimised cruciform specimen with Automated Machine Learning (AutoML). Our results demonstrated that 99.2% (54,536 of 54,976) of the quantified errors are less than 5%. Quantifying alignment deviations for an in-plane biaxial test system has been solved. The quantified method of alignment deviations could enhance the reliability of test data, improve assembly efficiency, and aid in constructing failure criteria of materials under biaxial stress.

Energy-based universal failure criterion and strength-Poisson's ratio relationship for isotropic materials

The prediction of material failures has been one of the most important topics in engineering design since the onset of human civilization. To date, a plethora of failure criteria have been developed, particularly for homogeneous isotropic materials. However, many of them have limited usage for specific groups of materials, are obscure in their origin, or different from the actual phenomena at the microscopic and macroscopic scales. Therefore, based on the most fundamental concept of energy, this study aims to establish a universal failure criterion for homogeneous full-density isotropic materials. The developed failure criterion requires three independent load-bearing capabilities of the material, that is, tensile (T), compressive (C), and shear (S) strengths, as criterion calibrators for applicability to a wide range of materials, including those with extremely ductile to exceedingly brittle behaviors. Energy and polynomial invariants expansion approaches were used to formulate the universal failure criterion, and both yielded a perfect dual relationship. The criterion in the energy form revealed a new physical insight into the zero-energy bound or fracture criterion, which corresponds to an intrinsic cut-off plane in a failure envelope. Comparisons between the experimental data across a broad spectrum of material types and the proposed failure criterion were in excellent agreement in both the stress and energy spaces. The strength-Poisson's ratio relationship was also derived for the first time, demonstrating that only two strength properties are independent and that three important bounding conditions for isotropic materials exist: (1) S/C = 0 when T/C = 0; (2) when T/C = 1 and S/C = 1/3, Poisson's ratio v = 0.5; and (3) v = −1 when T/S and C/S approach zero.

3D finite element simulation for tool temperature distribution and chip formation during drilling of Ti6Al4V alloy

A comprehensive 3D finite element simulation study has been conducted to investigate the tool temperature distribution along cutting edge and chip formation during drilling of Ti6Al4V alloy by using commercial finite element software Abaqus/Explicit. The Johnson–Cook material constitutive model and material failure criterion were implemented across the formulations to achieve the tool temperature and chip formation in the drilling process. The effect of different mesh sizes on simulation results was also analyzed. To assess and verify the accuracy of the simulation model, the corresponding experiment studies were carried out by measuring the thrust force, tool temperature, and chip morphology. Compared results show that the predicted thrust force, temperature distribution, and chip morphology are in good agreement with those tested from experiments. According to the combination of both simulations and experiments, it can be not only found the whole varying pattern of the thrust force but also reveal that the temperature decreases from drill center to outer corner along the primary cutting edge. In addition, it can provide a more detailed and profound knowledge about chip formation. All these are assumed to be recommendations for the optimization of tool geometry and drilling processing.

Ice load prediction of a podded propulsor under the dynamic azimuthing condition

In the process of cutting an ice layer by dynamic azimuthing of a podded propulsor, the unsteady and high pulsation characteristics of the ice load may compromise the safety and structural strength of podded propulsors. In this study, the failure criterion of simulated materials for the ice-breaking problem and the ice load calculation method were derived based on the peridynamics and the idea of panel division. The contact judgment method between the propeller and ice under the dynamic azimuthing condition of the podded propulsor was proposed. A numerical calculation model of the milling action of the ice–podded propulsor was established, and a numerical simulation of the ice–propeller milling process under the dynamic azimuthing conditions of the podded propulsor was realized. Moreover, numerical simulations under different ice layer moving velocities, propeller rotational speeds, podded propulsor azimuthing rates, and azimuth angles were carried out, and the ice layer breaking phenomenon and the variation characteristics of the propeller ice load under the dynamic azimuthing condition of the podded propulsor were obtained. The research results can guide technical support for the load evaluation, structural safety analysis, mechanism research of load components, and the selection of polar navigation steering strategies for ice-class podded propulsors.

Can the finite fracture mechanics coupled criterion be applied to V-notch tips of a quasi-brittle steel alloy?

Structures made of steel alloys with V-notches may fracture at the V-notch tip at which a small plastic zone usually evolves. Failure criteria for predicting fracture loads for such quasi-brittle alloys, as a function of the V-notch opening angle are very scarce and have not been validated, to the best of our knowledge, by a set of experimental observations.Herein we provide a database of experiments performed on AISI 4340 steel alloy specimens with three different V-notch opening angles and three different tempering temperatures, loaded in mode I. Material properties, failure load and plastic area at the V-notch tip are detailed.The experimental observations are used to investigate to which extent the finite fracture mechanics coupled criterion (FFMCC) for brittle materials may predict the failure load of quasi-brittle steel alloys, depending on the plastic zone size. Finite element analyses were used to compute the parameters required by the FFMCC. We compared the predicted versus the experimental fracture load for the different V-notch opening angles and tempering temperatures.For small opening angles (30°) for which the plastic area is very small, the FFMCC under-predicts the fracture load by about 20% which is within the experimental error range. The under-prediction of the failure load constantly increases to ∼ 50% as the V-notch angle increases to 90° and plastic zone area on the surface increases to ∼0.5mm2 (for a V-notch depth of 5 mm).The detailed experimental database is suggested to be used for validation purposes when new failure criteria for quasi-brittle materials are developed.

Long-term creep behavior of a short carbon fiber-reinforced PEEK at high temperature: Experimental and modeling approach

In this work, the time-dependent mechanical behavior of a short carbon fiber-reinforced PEEK is investigated at temperatures near and above the glass transition temperature and for stresses below the damage threshold. An experimental procedure including creep/recovery tests and dynamic mechanical tests was carried out by varying stress levels, temperatures and fiber orientation. The mechanical behavior is shown to be linear viscoelastic below the damage threshold. Effect of the fiber orientation on elastic and viscoelastic behavior is similar. A procedure involving the time–temperature superposition principle (TTSP) is set to assess the long-term linear viscoelastic behavior and is shown to provide reliable results. A Maxwell Generalized model is used for unidirectional identification of the model’s parameters. It is then implemented via a UMAT in Abaqus with failure criteria for viscoelastic materials from the literature for 3D calculation of industrial parts.