Maximum Stress Failure Criterion Research Articles

Experimental investigation on shear behavior of double-row perforated GFRP rib connectors in FRP-concrete hybrid beams

Perforated GFRP rib (PFR) connectors have been used in FRP-concrete hybrid beams due to durability and ease of construction. PFR connectors are parallel FRP plates with predrilled holes positioned in the flange of FRP beams. The optimal plate spacing needs to be determined because it affects the shear performance of PFR connectors. 18 push-out tests were conducted to investigate the effect of plate spacing ( Sl), penetrating GFRP bar diameter ( d), and concrete strength ( fc) on the failure mode, capacity, and shear load-slip (P-S) curves of double-row PFR connectors. Results showed that PFR connectors suffered plate shear failure with the concrete dowel undamaged. Typical P-S curves consisted of micro-slipping and significant-slipping phases. The shear capacity and stiffness of PFR connectors were improved by 33.3% and 45.1%, respectively, by increasing the plate spacing from 1.2 h (where h denotes the plate height) to 3.2 h. The effect of plate spacing on shear capacity and stiffness could be neglected if the ratio ( Sl/ h) was more than 3.2. Specimens with a larger diameter of penetrating bar and higher concrete strength demonstrated higher capacity and stiffness. An empirical equation based on the maximum stress failure criterion was proposed to estimate the capacity of PFR connectors, considering the plate spacing effect, and verified by available data. Additionally, a description of the P-S curve was developed and calibrated by the experimental results.

Multiscale Progressive Failure Analysis for Composite Stringers Subjected to Compressive Load.

The fiber-reinforced composite stringer is commonly used in large civil aircraft wing structures. Under compression loads, it exhibits complex failure modes, with matrix cracking being one of the most common. The quantitative analysis of matrix failure is important and difficult. To address this issue, a multiscale method combining the generalized method of cells (GMC) and macroscopic FEM models is employed to quantitatively predict matrix damage and failure. The extent of matrix damage in the composite structure is represented by the number of failed matrix subcells within the repeating unit cells. The 3D Tsai-Hill failure criterion is established for the matrix phase, and the maximum stress failure criterion is applied to the fiber subcell. Upon meeting the criterion, the stiffnesses of the failed subcells are immediately reduced to a nominal value. In the current study, the ultimate loads, failure modes and load-displacement curves of composite stringers subjected to compressive load are obtained by the experiment approach and the proposed multiscale model. The experimental and simulation results show good agreement, and the multiscale analysis method successfully predicts the extent of matrix damage in the composite stringer under compressive load. The number of failed matrix subcells quantitatively evaluates the damage extent within a 2 × 2 GMC model. The findings reveal that matrix subcell failures primarily occur in the 45° and -45° plies of the middle part of the stringer composite.

Enhancing accuracy of predictive fatigue life model in rejuvenated RAP binders through LAS test and complex modulus test at multiple temperatures

The linear amplitude sweep (LAS) test is widely accepted as a valuable tool for assessing binder fatigue. However, due to the binder's viscoelastic nature, the fatigue life varies with temperature, leading to a challenge in determining the LAS testing temperature. This research primarily addressed inaccurate assumptions of a linear relationship between the logarithms of the storage modulus (logG′(ω)) and angular frequency (log (ω)), as well as intermediate testing temperature. Then, by performing the LAS test at four different temperatures on rejuvenated RAP binders, a method for determining the rejuvenated RAP binder's fatigue behavior was introduced. The results demonstrated that LAS parameters, including A and B, correlated linearly at various temperatures with the rejuvenated RAP binder's complex modulus (|G*|) calculated at corresponding temperatures. Therefore, a fatigue life model, considering strain level and temperature effects, was developed using a power function of |G*|. It was found that the residual analysis exhibited a lack of fit, indicating that the linear model was inadequate throughout the whole range of experimental frequencies at multiple temperatures. Moreover, the newly introduced model predicted fatigue life more accurately at various temperatures utilizing the maximum stress failure criterion and the 35% damage level. This model will allow the LAS procedure to be used in a wider range of temperatures and strain levels for which rejuvenated RAP binders are used in the flexible pavement.

Coupled TMD modeling of cryogenic treatment of borehole in coal under confinement

Cryogenic fracturing using liquid nitrogen (LN2) is a waterless fracturing technology that is under extensive research nowadays given the high demand of environmental-friendly development of unconventional oil and gas resources. Excluding the exerted hydraulic pressure, the initiation and propagation of cryogenic fractures in rock materials largely depend on thermal stress generated by LN2 and the rock properties. So far, there are quite a few experimental studies elaborating on the cryogenic fracturing process of coal rocks; however, modeling studies on the topic are still very preliminary with no damage quantification. This study first set up a coupled thermo-mechanical (TM) modeling procedure by solving the heat conduction and rock mechanics equations in a serial manner and incorporating the maximum principal stress failure criterion. Then the numerical stability of this modeling procedure was examined through time step and grid resolution tests, and the model accuracy was corroborated by analytical solutions. Furthermore, the damage criterion was quantitatively validated against our experimental observations. Using this thermo-mechanical damage (TMD) modeling procedure, a systematic examination of the effects of key factors on cryogenic circulation treatment of coal rock borehole was carried out using realistic parameters. Trends and patterns of the cryogenic damage upon key factors, including realistic temperature boundary with the Leidenfrost effect, Young's modulus, thermal expansion coefficient, Poisson's ratio, specific heat capacity, density, thermal conductivity, in-situ stresses, and initial temperature of the coal rocks have been revealed and discussed. The modeling results herein are of great significance to understand the mechanisms of cryogenic fracturing of coal rocks, and this TMD modeling procedure could be further expanded to evaluate and optimize cryogenic treatment process of coal seams in field pilot tests.

On Nonlinear First Ply Failure Study of Laminated Composite Thin Skewed Hypar Shell Roofs

The skewed hypar shells have gained immense popularity in practical civil engineering fields due their highly aesthetic look. Light weight laminated composite material has increased its wide acceptance day by day in practical structures by virtue of superior material properties like high strength, high stiffness to weight ratio, prolonged fatigue life etc. Different types of bending as well as free and force vibration studies of laminated composite skewed hypar shells were done by earlier researchers. In some literatures, the first ply failure was also investigated using geometric linear strains only. So, the present paper aims to study the first ply failure behaviour of laminated composite skewed hypar shell roofs considering geometric nonlinearity. An eight noded isoparametric curved finite element having five degrees of freedom at each node is used here for finite element method. To establish the correctness of the present approach different benchmark problems are solved in this paper. Various types of lamina stacking sequences are taken up by the authors’ problems for first ply failure analysis of symmetric and antisymmetric skewed hypar thin shells with practical boundary condition. Along with the maximum stress and maximum strain failure criteria the authors use interactive failure criteria like Hoffman, Tsai-Hill and Tsai-Wu criteria as well as failure mode based criteria like Hashin and Puck criteria for the present study. The results obtained from this numerical investigation are analysed and post processed from different engineering standpoints to extract meaningful conclusions regarding first ply failure behaviour of the composite skewed hypar thin shells and to arrive at important practical guidelines which are expected to be beneficial for practicing civil engineers.

A Multiaxial Fatigue Damage Model Based on Constant Life Diagrams for Polymer Fiber-Reinforced Laminates.

In the last decade, fatigue damage models for fiber-reinforced polymer composites have been developed assuming the fracture energy equivalence hypothesis. These models are able to predict a fatigue life of composite laminates, but their identification requires a significant number of off-axial tests for various stress ratios. The present study proposes the stress ratio dependent model, which phenomenologically adopts a decrease in stiffness and residual strength of a unique ply according to experimental constant life diagrams. Hashin, Tsai-Hill, and the maximum stress failure criteria are utilized for damage initiation considering the residual strength of the ply. The obtained results indicate a sufficiency of using S-N curves for UD 0°, UD 45°, and UD 90° for identification of the model. The model was verified by S-N curves for UD 10°, UD 15°, and UD 30° and its applicability was demonstrated for prediction of a fatigue life of composite laminates with an arbitrary lay-up. The model is implemented into ABAQUS finite element software as a user subroutine.

Experimental and numerical study on the effect of electrohydraulic shock wave on concrete fracturing

In order to apply electrohydraulic shock wave (EHS) technology to oil and gas stimulation or assisted rock fracture, it is necessary to analyze how the crack propagation behavior of the rock subjected to the EHS. For this purpose, experiments and numerical simulations are carried out respectively. In the experiment, the relevant parameters of electrical characteristics and acoustic radiation characteristics were given based on the established discharge platform, and 30 times impacts tests are carried out on cubic concrete. The results show that the corner areas of the upper surface of the concrete are the first to be broken; with the increase of impact time, the shape and number of cracks on the surface of the concrete sample change in two stages. In the first stage, the number of microcracks increased rapidly, the cracks are interconnected, and the existing pores gradually become bigger. In the second stage, the growth rate of the number of microcracks gradually decreases, and the width of the formed cracks gradually increases; the damage variable of the concrete obtained by the acoustic test increases sharply first and then increase slowly throughout the impact test. In the numerical simulation, the history match of the EHS pressure is implemented based on the equivalent explosion method (EEM); a two-dimensional numerical model is established to simulate the interaction process between the EHS and the concrete sample; a three-dimensional TNT-water-concrete numerical model is built to simulate the concrete fracturing. The results show that it is reliable to use the equivalent explosion method to simulate the EHS. The concrete sample subjected to the EHS is affected by four aspects: bubble; transmitted wave and reflected wave; diffraction wave; elastic precursor wave and plastic loading wave. When the element deletion method is used to simulate crack generation, adopting the maximum tensile stress failure criterion can accurately simulate the final distribution of cracks, but it is difficult to simulate the evolution process of cracks under cyclic impact loads.

Multi-Scale Nonlinear Progressive Damage and Failure Analysis for Open-Hole Composite Laminates

In order to study the nonlinear behaviors and interactions among the constituents for the composite material structure under the tensile load, multiscale damage model using generalized method of cells (GMC) and a lamina-level progressive damage model were established, respectively, for fiber reinforced composite laminates with a central hole, which were based on the thermodynamic Schapery Theory (ST) at either the micro-level or the lamina level. Once the nonlinear progressive degradation of the matrix material reached the lower limit value for the ST method, matrix failures naturally occurred, the failure of the fiber was determined by the maximum stress failure criterion. For the multiscale progressive damage model, the GMC model consisting of a fiber subcell and three matrix subcells was imposed at each integral point of FEM elements, and the three matrix subcells undergo independent damage evolution. The load versus displacement curves and failure modes of the open-hole laminates were predicted by using the two progressive failure models, and the results were compared with that obtained by the Hashin-Rotem progressive failure model and the experimental results. The results show that the ST based method can obtain the nonlinear progressive damage evolution states and failure states of the composite at both the lamina level and the multiscale level. Finally, the damage contours and failure paths obtained are also presented.

Failure criteria assessment of carbon/epoxy laminate under tensile loads using finite element method: Validation with experimental tests and fractographic analysis

The failure of polymer composites is complex due to the independent and interacting damage mechanisms. The availability of several failure criteria demands a reasonable discernment of each criterion in order to obtain a consistent response to make an assertive selection. The importance of this decision is present in simulation works using finite element method and it is of particular interest of the industry and designers, once an optimized project is the goal. This study regards a carbon/epoxy laminate based on plain weave fabric subjected to tensile load and numerical simulations using finite element method was applied to compare the widely used Maximum Stress, Tsai-Wu, Hoffman, Tsai-Hill, Hashin and Puck failure criteria. Experimental tensile tests were carried out and fractographic analysis was performed in order to validate the finite element model and the applicability of the failure criteria. The model presented a good agreement with the experimental results and the correlation between the fractographic analysis and the failure criteria results allowed to select the Puck criterion as the proper and adequate for the studied composite laminate subjected to tensile load.

Using the Kriging Response Surface Method for the Estimation of Failure Values of Carbon-Fibre-Epoxy Subsea Composite Flowlines under the Influence of Stochastic Processes

This paper investigates the use of the Kriging response surface method to estimate failure values in carbon-fibre-epoxy composite flow-lines under the influence of stochastic processes. A case study of a 125 mm flow-line was investigated. The maximum stress, Tsai-Wu and Hashin failure criteria was used to assess the burst design under combined loading with axial forces, torsion and bending moments. An extensive set of measured values was generated using Monte Carlo simulation and used as the base case population to which the results from the response surfaces was compared. The response surfaces were evaluated in detail in their ability to reproduce the statistical moments, probability and cumulative distributions and failure values at low probabilities of failure. In addition, the optimisation of the response surface calculation was investigated in terms of reducing the number of input parameters and size of the response surface. Finally, a decision chart that can be used to build a response surface to calculate failures in a carbon fibre-epoxy-composite (CFEC) flow-line was proposed based on the findings obtained. The results show that the response surface method is suitable and can calculate failure values close to that calculated using a large set of measured values. The results from this paper provide an analytical framework for identifying the principal design parameters, response surface generation, and failure prediction for CFEC flow-lines.

Effect of aging and temperature on milling-induced stresses and cracks in Hot Mix Asphalt (HMA) pavements

The majority of the pavements in the world are surfaced with asphalt mixes. Milling is a necessary step for the removal of aged or distressed Hot Mix Asphalt (HMA) materials and recovery of Reclaimed Asphalt Pavement (RAP) for rehabilitation of asphalt pavements. The objective of this study was to predict the milling-induced stresses for two asphalt mixes. Using laboratory-measured stiffness, a three-dimensional finite element model (3-D FEM) was developed and validated with drop tower impact tests. The models were simulated at 25 °C and 60 °C, with unaged, 60 months, and 120-month aged conditions. Viscoelastic and Drucker-Prager models with the maximum principal stress failure criterion and the erosion method were utilized to predict failure. Results showed that the milling-induced stress zone increases significantly with increased stiffness/aging. Milling at 25 °C results in greater stress penetration depth than at 60 °C and leads to the formation of cracks below the milling line.

Design and Analysis of a Laminated Composite Tube

Piping is an important material for fluid transportation in modern industry, and well-structured piping can reduce losses due to maintenance and replacement downtime. Therefore it is necessary to design and analyze the pipes in order to optimize their structure. This paper focuses on composite laminated pipes. In this design case, the structural analysis of this pipe will be carried out by applying the laminate theory, and the structural analysis model will be established by using Mathcad software. The stress and strain of each laminate will be calculated by entering the winding angle and the corresponding equations in this software. The final optimal winding Angle can be determined by verifying the winding angles that can be maintained under maximum stress failure criteria using Mathcad contours and detailed tables of winding and torsion angles.

Development of Abaqus WCM plugin for progressive failure analysis of type IV composite pressure vessels based on Puck failure criterion

The type IV composite pressure vessels (CPVs) are used as a reliable solution for storing compressed gas but still require research and development to reach commercial advancements. The main two challenges in the design of CPVs are: a) debonding of liner and composite shell during the curing process, and b) accurate finite element modeling of the thickness and angle variation of helical layers at the dome regions. In this study, debonding of composite shell from polymeric liner and bosses due to the temperature variations during the curing process is simulated by using bilinear cohesive law. Regarding the second challenge, the Abaqus WCM plugin is used to model the actual geometry of two-liter type IV CPV’s domes by defining and controlling manufacturing parameters. The UVARM subroutine is developed to apply stress analysis and predict the damage initiation using the Maximum Stress, Tsai-Wu, Tsai-Hill, Hashin, and Puck failure criteria. Also, a USDFLD subroutine is written to implement progressive failure analysis using the Puck failure criterion with sudden material degradation model. The numerical axial and radial displacements as well as burst pressure results are compared with the experimental results available in the literature. A good correlation is observed between the finite element and experimental results. Also, numerical results showed that the initial debonding gap due to curing does not affect the progressive damage of the composite shell.

Comparative assessment and numerical simulation of boiler shell materials

Boilers are prone to both longitudinal and circumferential stresses. Hence, the need for better materials has been constant. Corrosion and stress failure due to extreme temperature conditions are common threats. Therefore, in the present research, numerical simulation and mechanical properties of various boiler shell materials have been highlighted. The results and conclusions have been obtained using the finite element analysis software ANSYS for commonly used boiler materials. The materials selected were Stainless Steel, Aluminum Alloy, and Composite materials. The Equivalent Stress (Von-Mises Stress) and Maximum Stress Failure criterion were used to identify the ultimate strength of all three materials. Findings indicated Structural Steel as safer when compared to other materials in terms of Equivalent Stress (Von-mises Stress). In addition, Titanium Alloy is extremely resistant to corrosion. As far as weight consideration, Aluminum alloy was the lightest among all three.

Study on the Shear Failure of Reinforced Concrete Beams Using Extended Finite Element Method (XFEM)

This research concerns with the fracture behavior of reinforced concrete beams without shear reinforcement numerically. The software ABAQUS is adapted to simulate the crack propagation using the eXtended Finite Element Method (XFEM), taking into account materials nonlinearities using concrete damage plasticity CDP criteria. XFEM is used to solve the discontinuity problems in the simulation. The maximum principal stress failure criterion is selected for damage initiation, and an energy-based damage evolution law based on a model-independent fracture criterion is selected for damage propagation. The traditional nonlinear finite element analysis is used to specify the crack initiation position, which is required to specify the crack location in the analysis of beams using XFEM. Three-dimensional reinforced concrete beam models are investigated subjected to three and four-point loading tests. Simply supported beams under the effect of applied static load are investigated. An elastic perfectly plastic model is used for modeling the longitudinal steel bars. The main variables considered in the study are beam depth and the shear span with beam length. The numerical results are compared with the available experimental results to demonstrate the applicability of the model. The XFEM provides the capability to predict the concrete member fracture behavior.

Modelling asphalt binder fatigue at multiple temperatures using complex modulus and the LAS test

ABSTRACT The linear amplitude sweep (LAS) test is useful for evaluating the fatigue of asphalt binders. In this paper, the combined effects of strain and temperatures are investigated, and a method for estimating binder fatigue behaviour is introduced at different temperatures from limited measurements. LAS tests were conducted on several different PG-grade binders at four different temperatures. The results show that LAS parameters A and B at different temperatures maintain a linear relationship with the binder complex modulus (G*) measured at corresponding temperatures. Therefore, a fatigue life model, accounting for strain level and temperature, is proposed using a power function of the binder G*, which can account for temperature effects. To verify the model, its parameters are fitted using test data at two temperatures were used to predict the fatigue life at additional temperatures. This study findings offer a simpler and reliable method to predict the values of fatigue life at new temperatures using both 35% damage level and maximum stress failure criteria that are recommended in AASHTO TP101-12 and AASHTO TP101-14, respectively. The new prediction method will allow a wider use of the LAS procedure regarding the effects of temperature and strain level for which binders are subjected to the pavement.

Effects of infill patterns on the strength and stiffness of 3D printed topologically optimized geometries

PurposeMechanical anisotropy associated with material extrusion additive manufacturing (AM) complicates the design of complex structures. This study aims to focus on investigating the effects of design choices offered by material extrusion AM – namely, the choice of infill pattern – on the structural performance and optimality of a given optimized topology. Elucidation of these effects provides evidence that using design tools that incorporate anisotropic behavior is necessary for designing truly optimal structures for manufacturing via AM.Design/methodology/approachA benchmark topology optimization (TO) problem was solved for compliance minimization of a thick beam in three-point bending and the resulting geometry was printed using fused filament fabrication. The optimized geometry was printed using a variety of infill patterns and the strength, stiffness and failure behavior were analyzed and compared. The bending tests were accompanied by corresponding elastic finite element analyzes (FEA) in ABAQUS. The FEA used the material properties obtained during tensile and shear testing to define orthotropic composite plies and simulate individual printed layers in the physical specimens.FindingsExperiments showed that stiffness varied by as much as 22% and failure load varied by as much as 426% between structures printed with different infill patterns. The observed failure modes were also highly dependent on infill patterns with failure propagating along with printed interfaces for all infill patterns that were consistent between layers. Elastic FEA using orthotropic composite plies was found to accurately predict the stiffness of printed structures, but a simple maximum stress failure criterion was not sufficient to predict strength. Despite this, FE stress contours proved beneficial in identifying the locations of failure in printed structures.Originality/valueThis study quantifies the effects of infill patterns in printed structures using a classic TO geometry. The results presented to establish a benchmark that can be used to guide the development of emerging manufacturing-oriented TO protocols that incorporate directionally-dependent, process-specific material properties.

Simulating quasi-static crack propagation by coupled peridynamics least square minimization with finite element method

In this work, we present an innovative simulation method for quasi-static crack propagation in mixed-mode, within a new framework of coupled peridynamics least square minimization and finite element method (PDLSM–FEM). As the inertia effect is neglected for quasi-static problems, the governing equations for PDLSM–FEM can be solved implicitly without iterations. Displacements and stresses from PDLSM–FEM are used to compute the interaction integral, an extended version of the J-integral. The stress intensity factors (SIFs) are derived from the interaction integral and used in the maximum circumferential tensile stress failure criterion to predict the onset of crack propagation and the direction of propagation. New contributions in this work include the following: (1) developing a new framework for coupling PDLSM and FEM; (2) pioneering a quasi-static method for simulating crack propagation in peridynamics; (3) developing an element-based approach for selecting the interaction integral contour; and (4) proposing and implementing an innovative method for handling peridynamic bond breakage and crack growth. Quasi-static crack propagation simulation in this work provides a computationally efficient way to find the shape of the crack, and the current PDLSM–FEM model is straightforward and can be easily introduced into commercial finite element codes. Three numerical examples are carried out, and the results show that the proposed method evaluates SIFs accurately and captures crack growth as expected.

Modelling effects of aging on asphalt binder fatigue using complex modulus and the LAS test

The linear amplitude sweep (LAS) test is considered a useful tool for evaluating fatigue of asphalt binders. It has been confirmed that a good correlation exists between fatigue performance of binders and mixtures in a few studies. While the change in binder fatigue with load or strain level is well studied and modeled, the effects of oxidative aging remain difficult to explain or to model in a simple format. In this paper, the combined effects of strain and aging are investigated and a method for estimating binder fatigue behavior after different aging durations from limited measurements is introduced. LAS tests were conducted on eight binders at three different aging periods in the PAV. It is found that binder fatigue damage parameters C1 and C2 have a good linear relationship with aging level when using the dissipated pseudo-strain energy approach. The results also show that LAS parameters A and B at different aging duration maintain a linear relationship with the binder complex modulus (G*) measured at corresponding aging conditions. Therefore, a new fatigue life (Nf) model accounting for strain level and aging effect is proposed using a power function of the binder G*. To verify the model, its parameters are fitted using test data at first two aging conditions and used to extrapolate and predict the fatigue life at extended aging conditions. This study findings offer a simpler and reliable method to predicted values of fatigue life at new aging condition using both 35% damage level and maximum stress failure criteria that are recommended in AASHTO TP101-12 and AASHTO TP101-14, respectively. The new model will allow use of the LAS procedure to a wider range of aging and strain level conditions for which binders could be subjected to in the pavement.

On the stochastic first-ply failure analysis of laminated composite plates under in-plane tensile loading

This paper highlights the amount of risk taken when a deterministic approach is used in designing composite structures without consideration of stochastic effects. The study treats all material and geometric parameters of the composite laminated plates under investigation as stochastic. Monte Carlo simulation is employed to investigate the stochastic effects of material properties, ply thickness, and ply orientation on the failure of laminated composite plates under static loads. Classical lamination theory is used to calculate the strength ratios using maximum stress, Tsai-Hill, and Tsai-Wu failure criteria for plates of three different materials in various stacking sequences. Variation in the failure ply distributions are shown to increase with coefficient of variation of the input variables. A positive linear trend between the coefficients of variation of the strength ratio and input variables is found, whose slope increases as randomness is considered for more input variables. Probability of failure and failure ply distributions are shown to be heavily dependent on the combination of laminate stacking sequence, material, and failure probability. In particular, while the empirical failure probability for cross-ply laminates is highest for the ply predicted by a deterministic analysis, this probability decreases rapidly with increasing variation in input parameters. Further, the failure of unexpected plies for cross-ply laminates is shown to be related to the stiffness ratios of the plies. The general significance of considering ply thickness and ultimate strength as random variables is also demonstrated, as well as the significance of randomness in ply orientation for balanced and angle ply laminates.