Common Failure Criteria Research Articles

Mechanical properties of recycled aggregate concrete reinforced with steel fibers under triaxial loading

The use of steel fiber reinforced recycled concrete (SFRAC) can help achieve resourceful reuse of construction waste and environmental sustainability. However, SFRAC structural members may experience complex stress states. Therefore, triaxial compression tests were conducted on 168 cylindrical SFRAC specimens to investigate their mechanical properties. The failure modes, stress-strain behavior, strength, and deformation of SFRAC under triaxial compression were observed. The effects of lateral confining pressure, steel fiber (SF) content, and recycled coarse aggregate (RA) replacement rate on these properties were analyzed. The internal micro-morphology of SFRAC was analyzed using SEM to better understand its failure mechanism under compression. The result shows that an increase in lateral confining pressure alters the failure mode of SFRAC specimens, resulting in a significant increase in peak strength and ductility. The enhancement of the elastic modulus by steel fibers decreases as the lateral confining pressure increases, suggesting a coupling effect between the two parameters. The inclusion of steel fibers in SFRAC did not have a significant impact on its failure mode or compressive strength. And yet, it did increase the ductility and toughness of the material, with an optimal steel fiber content of 1 % (by volume). On the other hand, the addition of recycled coarse aggregate resulted in a significant reduction in the concrete's compressive strength, by almost 17 %. Finally, several common material failure criteria for concrete were used to evaluate the impact of RA substitution rate and SF content on the strength of SFRAC. The Willam-Warnke failure criterion showed a higher strength. These findings provide a theoretical basis for future engineering applications of SFRAC.

Research progress of evaluation methods of failure criteria for fiber reinforced composites

Integration of composite materials in aviation applications undeniably offer multiple important benefits, and more modelling techniques and failure analysis tools are increasingly being developed in evaluated to reduce the high costs associated with investigating the mechanical characteristics and prediction of failure of fiber reinforced composites. This article evaluates and compares between some of the most common failure criteria, Hashin, Puck and maximum stress criteria. The conclusion of this article shows that the interactive failure criteria are more adequate to use in the prediction of failure although they are inherently more complex to describe.

Consecutive-k1 and k2-out-of-n: F Structures with a Single Change Point

In the present paper, we establish a new consecutive-type reliability model with a single change point. The proposed structure has two common failure criteria and consists of two different types of components. The general framework for constructing the so-called consecutive-k1 and k2-out-of-n: F system with a single change point is launched. In addition, the number of path sets of the proposed structure is determined with the aid of a combinatorial approach. Moreover, two crucial performance characteristics of the proposed model are studied. The numerical investigation carried out reveals that the behavior of the new structure is outperforming against its competitors.

Equivalent confining stress-based strength model for concrete under triaxial compression

In order to predict the peak strengths for different strength grades, types, or shapes of concrete under equal or unequal triaxial compression, the concept of equivalent confining stress is firstly proposed and then its calculation method for concrete specimens in the shape of a cube, an annulus, or a cylinder is illustrated. Next, a straightforward power-law type of prediction model is developed based on the aforementioned equivalent confining stress by comparing the following three common failure criteria adopted in triaxial compression: the Mohr-Coulomb failure criterion, the Willam-Warnke failure criterion, and the Power-law failure criterion. Furthermore, a rich experimental database that covers a wide parameter range is established according to the triaxial test results reported in previous literature. The model is thoroughly evaluated after calibrating the coefficients in the modified Power-law failure criterion. From the subsequent evaluation result, the proposed model can provide an accurate prediction for concrete under uniform or non-uniform triaxial compression. Besides, it also works effectively for different strength grades, types, or shapes of concrete specimens. In fact, in different conditions, the mean ratios of predicted-to-test peak triaxial strengths are all around unity, and the degrees of volatility of predicted results are all at a low level. In brief, this easily usable equivalent confining stress-based strength model can accurately predict the peak triaxial compressive strengths of concrete.

A two-level strategy for simplification of fracture prediction in notched orthotropic samples with nonlinear behavior

In this paper, the load bearing capacity of U-notched specimens made of Russian pine wood, as a natural orthotropic material with nonlinear behavior, is investigated under pure mode I loading. The load bearing capacity of the orthotropic specimens with nonlinear behavior is predicted adopting a novel combination of the Equivalent Material Concept (EMC) and the Virtual Isotropic Material Concept (VIMC) in conjunction with the brittle failure criteria. By applying the EMC, the orthotropic material with nonlinear behavior is equated with a virtual linear one. Subsequently, using the VIMC, the orthotropic material with linear behavior obtained from the previous step is equated with a virtual isotropic material with linear behavior. Eventually, the load bearing capacity of the orthotropic nonlinear notched samples is predicted using two common brittle failure criteria, so-called the point stress criterion and the mean stress criterion. It is shown that both criteria employed for predicting the notch fracture toughness of the wood specimens are of good accuracy.

Tensile Properties and Manufacturing Defectives of Short Carbon Fiber Specimens Made with the FDM Process

With the fourth industrial revolution, Additive Manufacturing started to offer new possibilities of manufacturing, Fused Deposition Modeling being one of the most used processes for fabrication. In this paper, the studied specimens are manufactured based on the Fused Deposition Modeling (FDM) method, with a filament of short carbon fiber and polyethylene terephthalate (PET) matrix, with a variation of the layer thickness. For the resulted specimens the tensile properties are determined according to ASTM D638. The most advantageous results are obtained for the layer thickness of 0.15 mm, with the tensile strength of 58 MPa. Based on the stress-strain curves which are presented in this paper, it also can be assumed that the material is brittle. The results of the mechanical properties are very similar for each group of specimens and it can be assumed that the mechanical properties are homogenous due to the material quality and the machine performances. For all the specimens the rupture location is almost in the same area. Due to the difficulty of carbon fiber filament printing, the manufacturing defectives which appear during the manufacturing process are detected, the most common manufacturing defectives being the material gaps from each specimen, which are identified with microstructural analysis. As failure modes, the most common failure criteria are the delamination and the matrix cracks.

Elastic-plastic solutions for analyzing wellbore stability

Selecting a good practical prediction method of wellbore instability has extensively become an important issue in order to overcome the resulting instability problems during drilling. Therefore, the aim of this paper is to simulate the actual stresses around wellbore using elastoplastic rock behavior in order to describe the actual cases of wellbore instability problems. Description of stress state around wellbore is presented. Common failure criteria are also presented. Selection of the most applicable equations for description of stress state using elastoplastic rock behavior. Experimental data are used to calculate the cylindrical stresses surrounding the drilling hole wall at various diameters. Furthermore, a sensitivity analysis is done to test changing the radial stress with overbalance support and wellbore radius.

Comparative Analysis of Common Strength Criteria of Soil Materials.

In this paper, the common failure criteria of existing soil materials, such as the Mohr–Coulomb criterion, Drucker–Prager criterion, Lade–Duncan criterion, Matsuoka–Nakai criterion andAC-SMP criterion are systematically discussed, and the applicability of these criteria is quantitatively analyzed through the true triaxial test results of loess, so as to provide reference for the accurate selection of specific criteria in engineering practice. The failure criteria are classified from several aspects, such as whether the influence of the intermediate principal stress and the change of spatial moving plane are considered, analyzed and discussed, respectively. According to the true triaxial test results of undisturbed loess, the difference of strength criterion between the three-dimensional failure plane and p-q plane is analyzed, and based on the true triaxial test data of undisturbed loess, the error analysis of each failure criterion is carried out. The results show that the AC-SMP criterion is in good agreement with the test results, and can accurately evaluate the true triaxial test of loess. For different soil materials or different stress states, it is necessary to select appropriate failure criteria. This study shows how to choose the corresponding failure criterion under specific circumstances, so as to better satisfy the theory and practice and provide reference for engineering.

On the Closure of Aging Classes Under the Formation of Coherent Structures

In this paper, we study the closure property of the Increasing Failure Rate (IFR) class under the formation of coherent systems. Sufficient conditions for the nonpreservation of the IFRattribute for reliability structures consisting of [Formula: see text] independent and identically distributed ([Formula: see text] components are provided. More precisely, we deal with the IFR preservation (or nonpreservation) under the formation of structures with two common failure criteria by the aid of their signature vectors.

Experimental investigation of triaxial strength of ultra-high performance concrete after exposure to elevated temperature

Equipped with excellent strength and energy absorption capacity, ultra-high performance concrete (UHPC) is a promising material to improve structural resistance against extreme loads. Material and structural tests at ambient temperature have been conducted extensively on UHPC specimens in recent years, and its mechanical properties have been well-documented. In this study, a hybrid steel and polypropylene (PP) fibre reinforced UHPC is investigated under uniaxial and triaxial compression states after exposure to elevated temperatures. Cubic (50 mm) and cylindrical specimens (50 mm diameter × 100 mm height) were first heated in electric furnace to target temperatures, i.e. 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C. After naturally cooled down to ambient temperature, the specimens were tested under uniaxial compression and triaxial compression with confining pressure ranging from 5 to 40 MPa. The triaxial stress–strain relationships and failure modes after exposure to elevated temperatures were then compared and discussed. Several common failure criteria for concrete material were adopted to describe the high temperature effect on UHPC’s strength. An empirical model for reproducing the triaxial compression stress–strain curves of UHPC after elevated temperature was proposed.

Variation in Car Seat Tolerance Screen Performance in Newborn Nurseries.

Currently, car seat tolerance screens (CSTSs) are recommended for all infants born prematurely in the United States. Although many late-preterm infants are cared for exclusively in newborn nurseries (NBNs), data on implementation of CSTS in nurseries are limited. Our objective for this study was to determine management strategies and potential variation in practice of CSTS in NBNs across the nation. We surveyed NBNs across 35 states using the Better Outcomes through Research for Newborns (BORN) network to determine what percentage perform CSTSs, inclusion and failure criteria, performance characteristics, follow-up of failed CSTSs including use of car beds, and provider attitudes toward CSTS. Of the 84 NBNs surveyed, 90.5% performed predischarge CSTSs. The most common failure criteria were saturation <90%, bradycardia <80 beats per minute, and apnea >20 seconds. More than 55% noted hypotonia as an additional inclusion criterion for testing, and >34% tested any infant who had ever required supplemental oxygen. After an initial failed CSTS, >93% of NBNs retested in a car seat at a future time point, whereas only ∼1% automatically discharged infants in a car bed. When asked which infants should undergo predischarge CSTS, the most common recommendations by survey respondents included infants with hypotonia (83%), airway malformations (78%), hemodynamically significant congenital heart disease (63%), and prematurity (61%). There is a large degree of variability in implementation of CSTS in NBNs across the United States. Further guidance on screening practices and failure criteria is needed to inform future practice and policy.

Effect of micromechanical properties on the critical buckling load of woven composite plate: A multiscale analysis

Thin plate buckling is a common failure criterion in aerospace structures that occurs before the material reaches the yield limit (for metal alloys) or the first ply fails (for composites). In general, composites are widely adopted over metallic parts due to their lightweight nature with better strength quality, whereas the woven composites are chosen mainly for their multidirectional load-carrying capacity and excellent drape ability to shape complex structures over unidirectional composites. With the aid of the commercial software code Ansys, in this present study, a multiscale analysis is performed on a 16-layer quasi-isotropic symmetric woven composite plate under uniaxial compressive loading to examine the effect of microscopic parameters; namely, fiber volume fraction, yarn fiber volume fraction, yarn thickness and spacing based on twill and weave type unit cells (RVE). The current research reveals that both fiber volume fraction and yarn fiber volume fraction have a strong effect on the critical buckling load of the woven composite plates, while yarn thickness does not influence the critical buckling outcomes. In addition, choosing an appropriate value for yarn spacing can be crucial in increasing the buckling load capability of the woven composite plate.

Automated Dielectric Thermoscopy Characterization of Water-Contaminated Grease

Machine maintenance is important for improving machine uptime and reliability, and for reducing costs. Grease is used in most rolling element bearings, and one common failure criterion is water contamination, so developing a sensor that can detect water content automatically without human input could be a useful endeavor. The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this article with computer logged instrumentation. This method has been termed dielectric thermoscopy (DT). Several off-the-shelf (two lithium, one lithium complex, and two calcium sulfonate complex) and one unadditivized lithium grease are tested with varying amounts of water contamination from 0% to approximately 5%. Another grease is tested with small increments of added water from 0% to 0.97% to test the resolution of the measurement. The purpose is to use the capacitance temperature slope (termed dielectric thermoscopy) to show correlations to the water content of the grease sample and investigate whether any grease types will pose problems in the measurement. A small, custom-made fringe field capacitance sensor with an integrated temperature sensor has been used for this characterization, and data are logged automatically with laboratory equipment and a personal computer (PC). A useable and positive correlation to water content and the DT measurement of roughly 0.5 pF per 10 °C and percentage of water was found, although it was found that some greases have different behavior than others.

Fatigue properties and cracking mechanisms of a 7075 aluminum alloy under axial and torsional loadings

In this work, the fatigue properties of a 7075 aluminum alloy under axial and torsional loadings are investigated. For this purpose, fully reversed tension-compression as well as torsional fatigue tests were respectively conducted for polished dumbbell shaped specimens. The results of the tension-compression fatigue tests are first presented in the form of S-N plot, and the Basquin’s equation is used to describe the fatigue data. Based on fatigue design, the fatigue data obtained under axial loading are transformed to estimate the life for torsional fatigue by determining equivalent shear stress using common failure criteria including Tresca, von Mises and maximum principal stress. The curves predicted using these criteria are compared to the experimental data obtained under torsional loading. Scanning Electron Microscopy (SEM) was used to observe the fracture surfaces in order to examine the crack initiation and propagation process. Fracture surfaces are presented at both macroscopic and microscopic scales and failure modes are discussed with regards to the failure criteria commonly used for fatigue life prediction.

Strength failure criteria analysis for a flax fibre reinforced composite

Natural fibre composites are being utilized increasingly in high-performance, structurally demanding applications, in part because of their material properties and in part because they are a more sustainable choice compared to other engineering materials. However, there is a current lack in understanding of best practices for strength modelling of natural fibre composites. This study aims to understand how well common failure criteria predict strength in multidirectional flax fibre composite laminates. Four failure criteria are compared to experimental data from tension and compression tests of flax composite laminates with five different layups. Parametric optimization is performed on each criterion in order to determine the optimal strength, stiffness, and interaction parameters. In conclusion, the Hashin and Puck failure theories are recommended because they have the smallest error compared to experimental data. Values for parallel-to-fibre shear strength are also presented, and they are found to be comparable to the shear strength of conventional glass fibre composites with similar matrix materials.

Target Safety System design for the ESS target station

The European Spallation Source (ESS) will be a 5 MW neutron spallation research facility where an energetic proton beam incident upon a helium-cooled tungsten target is converted to neutron beams. The liquid hydrogen moderator, water moderator, and reflector systems within the target monolith slow the high-energy spallation neutrons down to cold and thermal neutrons suitable for use by experiments. Several layers of control, protection, and safety systems will be implemented in order to ensure safe operation of this advanced facility. The Target Safety System (TSS) is part of the overall radiation safety plan for the Target Station. As such, in case of an abnormal event, the TSS will protect the public from exposure to unsafe levels of radiation, prevent the release of radioactive material beyond permissible limits, and bring the neutron spallation function into a safe state. This safe state is defined as no beam incident upon the target. Since the target is the source of the release of radiation in the presence of the beam, putting the target station into the safe state (no beam), brings the spallation process to the safe state.The TSS safety functions are based on the results from hazard and accident analyses done to evaluate radiation hazards within the target station. The most critical hazards are related to increased temperature of the target wheel tungsten, which can be the result of cooling system malfunctions or stopping of the rotating target. Therefore, the TSS will monitor parameters related to the cooling conditions and rotation of the target.As a safety system, the TSS is subject to requirements from the Swedish Nuclear Safety Authority (SSM), including single failure and common cause failure criteria. These requirements impact the system architecture in terms of redundancy, separation and diversity. Dedicated redundant and diverse TSS sensors are connected to two diverse and separated trains performing the same safety functions. Each train acts on diverse and separated mechanisms to stop the beam from reaching the target.This paper will describe the design and architecture of the TSS, which implements the safety functions identified in the radiation safety analyses and fulfils the SSM conditions.

Analysis of the bending effects and the biaxial pre-straining in sheet metal stretch forming processes for the determination of the forming limits

The most common failure criterion in sheet metal forming operations is the forming limit diagram (FLD). Typically, the FLD is evaluated with the Nakajima test, which is a stretch forming-based test that allows the analysis of stretching under different stress conditions. The results of the Nakajima tests are considered ideally achieved under linear strain path deformation. However, due to the hemispherical form of the punch, the induced strain path starts in biaxial condition and switches to a linear path after the first contact between punch and specimen. In addition, the strain distribution is evaluated on the outer surface of the specimen. Consequently, the results are affected by a non-linear strain path and a bending component due to the sheet thickness and punch diameter. These effects have a consequence on the FLD, and thus it is not directly comparable with the ideal FLD that is analytically evaluated since the analytical models in the literature do not consider the process effects like bending and the biaxial pre-straining. In this paper, a study of biaxial pre-straining and bending effects is observed for different stress conditions and materials. The investigation of the bending will be considered under the experimental and numerical aspect. Nakajima tests are conducted with different punch diameters to discover the effects of different material thickness to punch radius ratios. The results are also compared with the outcomes of a numerical model, used for the analysis of the strains on the outer, middle and inner layers. The biaxial pre-stretching is analysed by comparing the outcomes of the FLD achieved by the Nakajima punch with the results of the Marciniak test. In this paper, an efficient method based on the correlation coefficient for the evaluation of pre-straining is presented. The biaxial pre-stretching will be compared to the strain paths and the tendencies will be analyzed. Finally, considerations about the phenomenology of the effects in dependency of the material classes are given.

Numerical simulation of crack propagation and coalescence in pre-cracked rock-like Brazilian disks using the non-ordinary state-based peridynamics

In the non-ordinary state-based peridynamics (NOSB-PD), the maximum tensile stress criterion and Mohr-Coulomb failure criterion, which are common stress-based failure criteria in rock mechanics and rock engineering, are applied to distinguish the tensile cracks and shear cracks, respectively. The initiation and propagation and coalescence of one single crack or double cracks in the Brazilian Disk specimens under compressive line loads are investigated using NOSB-PD. The effects of the specimen sizes and the crack inclination angles on the peak failure loads of the pre-cracked Brazilian Disk specimens are studied. Mode I fracture toughness and mixed Mode I/II fracture toughness are evaluated using the suggestions by ISRM. Moreover, the effects of horizon size and material points spacing on crack propagation in Brazilian Disks are investigated to prove the accuracy of NOSB-PD. The present numerical results are in good agreement with the previous experimental and numerical results.

Computing Barlow-Proschan Importance in Combined Systems

This paper is concerned with the computation of the Barlow-Proschan importance measure for systems involving two common failure criteria, and consisting of statistically independent and identical components. The failure or survival of these systems generally depends on the number of consecutively failed or working components, or the total number of failed or working components in the whole system. The results are applied to $(n,f,k):{\rm F}$ and $ :{\rm F}$ systems.

Fatigue life and endurance limit prediction of asphalt mixtures using energy-based failure criterion

Fatigue cracking is one of the major types of distress in asphalt mixtures and is caused by the accumulation of damage in pavement sections under repeated load applications. The fatigue endurance limit (EL) concept assumes a specific strain level, below which the damage in hot mix asphalt (HMA) is not cumulative. In other words, if the asphalt layer depth is controlled in a way that keeps the critical HMA flexural strain level below the EL, the fatigue life of the mixture can be extended significantly. This paper uses two common failure criteria, the traditional beam fatigue criterion and the simplified viscoelastic continuum damage model energy-based failure criterion (the so-called GR method), to evaluate the effect of different parameters, such as reclaimed asphalt pavement (RAP) content, binder content, binder modification and warm mix asphalt (WMA) additives, on the EL value. In addition, both failure criteria are employed to investigate the impacts of these parameters in terms of the fatigue life of the study mixtures. According to the findings, unlike an increase in RAP content, which has a negative effect on the mixtures’ fatigue resistance, a higher binder content and/or binder modification can significantly increase the EL value and extend the fatigue life as was proved before by other researchers, whereas WMA additives do not significantly affect the mixtures’ fatigue behaviour. A comparison of the model simulation results with the field observations indicates that the GR method predicts the field performance more accurately than the traditional method.