Failure Analysis Research Articles

A Review on Failure Analysis of Date Palm Fiber Reinforced Polymer Composites

A Review on Failure Analysis of Date Palm Fiber Reinforced Polymer Composites

Failure Analysis of Abutment-Loaded Underground Coal Mine Stoppings during Explosion

Failure Analysis of Abutment-Loaded Underground Coal Mine Stoppings during Explosion

Novel triply periodic minimal surfaces sandwich structures: Mechanical performance and failure analysis

AbstractSandwich structures are known for their exceptional mechanical properties and widespread applications. This study integrates additive manufacturing (AM) technology, experiments, theoretical equations, and numerical simulations to investigate a novel lightweight sandwich structure with a core based on Triply Periodic Minimal Surfaces (TPMS). The core incorporates Primitive, Neovius, and Diamond structures and is designed and manufactured using AM. Three‐point bending experiments are conducted to assess bending performance, failure modes, and energy absorption capability. A numerical model is established to analyze behavior under bending loads, validated through comparison with theoretical equations and numerical simulations, focusing on stress concentration areas. A parametric study investigates the effects of skin material, thickness, and TPMS core relative density on bending performance and energy absorption capacity. Furthermore, a functionally graded core layer with a gradient change in relative density is designed to study its influence on bending performance. The parameters of the core have a decisive impact on TPMS sandwich panel performance. This study demonstrates that sandwich structures with TPMS cores can be designed to possess desirable bending performance and energy absorption capacity, providing insights for future engineering applications.Highlights A novel TPMS sandwich structure is fabricated using 3D printing technology. The gradient relative density core is introduced. The bending performance and failure behavior of the structure are evaluated. A parametric study was conducted to investigate the effects on performance.

Effects of drilling-induced defects on tensile damage evolution of CFRP laminates

The reliability and service safety of composite structures are compromised by drilling defects on carbon fiber reinforced polymer (CFRP) materials. However, the synergism effect of different types of drilling defects on the mechanical behavior of structures remains unclear. To address this gap, this study focuses on investigating the intralaminar and interlaminar tensile damage evolution response of open-hole CFRP laminates while considering drilling quality. A model is developed, incorporating drilling delamination and tearing defects using the LaRC05 failure criterion and extended finite element method (XFEM). The model implemented in Abaqus/Standard software and the UDMGINI user subroutine is validated through experimentation. Subsequently, three types of open-hole CFRP laminates with typical drilling defect factors are subjected to tensile failure analysis. The results show a notable decline in the mechanical performance of CFRP laminates when drilling defect factors exceed certain levels. Moreover, a progressive damage evolution pattern is analyzed for open-hole CFRP laminates with respect to ply stacking sequences. The interaction between interlaminar delamination propagation and intralaminar crack evolution paths is discussed, highlighting that the concentration of in-plane shear stress primarily influences the location of crack initiation in CFRP laminates.

On the experimental determination and prediction of damage evolution in composites via cyclic testing

This study introduces a novel approach to obtaining and predicting damage evolution laws using quasi-static cyclic testing within the framework of continuum damage mechanics. To achieve this, a comprehensive set of characterization and parameter identification tests was performed. Carbon-epoxy specimens were manufactured using the filament-winding technique, and these laminates were tested using a universal testing machine. Digital image correlation was employed in all experiments to capture strain fields, and an alternative method utilizing the combined loading compression device is presented to obtain mechanical properties. Once the material was characterized, cyclic tests were conducted, including [Formula: see text], [Formula: see text], and [Formula: see text] tensile tests, and shear v-notch tests. These aim to determine damage evolution laws for both conditions, pure and coupled stress states. From these tests, values for damage onset and threshold were obtained and used to define four new parameters. These parameters permit the estimation of degradation relationships for any arbitrary orientation without requiring additional tests. This approach was tested as the proof-of-concept within the positive range of transverse tension and in-plane shear stress domain. The obtained results are promising, justifying its extension to other failure mechanisms. While acknowledging its limitations, this new approach holds potential for implementation in the analysis of progressive failure in fiber-reinforced composite materials, possibly in conjunction with established failure criteria and computational tools, mainly in the finite element method domain.

Failure analysis of wellhead casing and optimization of slip hanger in ultra deep wells

Failure analysis of wellhead casing and optimization of slip hanger in ultra deep wells

Investigation on memory package crack and prevention under temperature cycling test

Memory package with multiple die stacking in one package faced package crack issue during package level temperature cycling test (TCT) and the failure cycle cannot meet reliability requirement. Failure analysis showed epoxy molding compound (EMC) cracking located at the center area of package surface. Finite element modeling and simulation was conducted to study package stress and failure mechanism under cyclic temperature loading condition. Simulation results showed that the center of package surface is subjected to higher stress and stress variation during stringent TCT test due to high and tight die stacking structure. Several parametric studies were conducted to further understand failure mechanism and provide solution for crack prevention. Design guideline was proposed to eliminate or reduce package crack risk for multi-chip package (MCP) in memory chip package.

Analysis of gas-cooled micro modular reactor (MMR) fuel

The gas-cooled micro modular reactor (MMR) is a novel concept with a compact fuel form consisting of thousands of tri-isotropic fuel (TRISO) particles dispersed in a silicon carbide matrix. The MMR fuel has a high volume packing fraction and is horizontally placed within graphite channels. This study demonstrates that the horizontal arrangement of MMR fuel within graphite channels resulted in a non-uniform gap between the fuel and graphite brick, leading to an "off-center" temperature distribution within the fuel, and resulting in differences in TRISO performance even within sub-zones positioned symmetrically in the radial direction. Given the complexity of the fuel structure and the challenges involved in simulation, a multi-scale and multi-physics coupled analysis method of MMR fuel was realized in this work by implementing physical models into the open-source finite element platform MOOSE. Thermal-mechanical analysis and failure analysis within sub-zones of the typical design MMR fuel during normal operation were conducted through simulation. The results indicate that higher-temperature sub-zones exhibit increased internal pressure within TRISO and show greater tensile stress in the Chemical Vapor Deposited Silicon Carbide (CVD-SiC) layer. Regarding fuel failure analysis, this work found limited impact from Pd penetration and kernel migration. Pressure-induced particle failure, closely associated with stress in CVD-SiC, emerges as the primary failure criterion. The probability of fuel failure is relatively low, and interfacial cohesive parameters have an impact on the SiC stress and the fuel failure probability at the highest level.

#494 Analysis of technique failure and reasons for the end of follow-up in a peritoneal dialysis unit

Abstract Background and Aims Currently, there are various definitions for peritoneal dialysis technique failure, and several related factors are described. There is controversy regarding whether mortality should be considered a form of technique failure or not, as it involves an event of a different nature. Besides, the exit form peritoneal dialysis (PD) technique can occur due to the transition to hemodialysis (HD), kidney transplantation or the patient's death in general. The aim of this study was to investigate which factors are associated with survival in peritoneal dialysis technique. Method A retrospective study was conducted with 111 incident PD patients in the dialysis unit of Hospital Universitario Virgen de las Nieves, in Granada, Spain, between 2015 and 2020. A survival curve was obtained, evaluating the association of different variables with technique failure and the end of follow-up. By identifying mortality as a competitive risk for technique failure, a Fine and Gray competitive risks model was applied. Results A total of 111 patients were analyzed, with an annual technique survival of 90%, being it 83% at two years, and 74% at three years. Table 1 reflects the demographic and clinical characteristics of the patients. The main causes of technique failure were psychosocial causes (19%), peritoneal catheter mechanical issues (12%), ultrafiltration failure (9.52%), and peritonitis (9.52%). The main reasons for the end of follow-up were kidney transplantation (55%), transfer to HD (26%), and death (12.6%). Among the deceased, 64% were of cardiovascular origin, and 21% were infectious. Technique failure was more observed in patients over 65 years old, in those with a Charlson index higher than 4 points, with diabetes, a history of cardiovascular disease (CVD) and heart failure (HF), in former smokers, and in diabetic kidney disease. Conclusion Technique survival in our center was 90% at one year and 83% at two years, similar to previous Spanish records. The reasons for technique exit were: 55% due to kidney transplantation, 26% due to transfer to hemodialysis, and 19% due to for psychosocial causes. Risk factors related to technique failure were advanced age, Charlson index, diabetes, and a history of cardiovascular disease (CVD) and heart failure (HF).

Failure Analysis of a Ball Milling Machine, Used for the Preparation of Cemented Carbide Composites

Failure Analysis of a Ball Milling Machine, Used for the Preparation of Cemented Carbide Composites

Preliminary Failure Analyses of Loaded Hot Water Bottles

Hot water bottles are widely utilised for their therapeutic advantages, such as relieving muscle tension and imparting warmth. However, the increasing frequency and potential risks associated with bursting or failure necessitate a detailed examination of the contributing factors as their failure is not fully understood in a scientific manner. With the apparent lack of analysis of hot water bottles in the literature, this study employs, for the first time, a dual methodology involving finite-element (FE) analysis conducted in ABAQUS and experimental validation to systematically investigate the underlying mechanisms leading to failure incidents. Through FE modelling and analysis, the stress and strain distribution within typical hot water bottles is modelled under compression loading conditions, facilitating the identification of vulnerable areas prone to failure. Experimental validation encompasses uniaxial loading compression tests on distinct specimens, generating load–displacement curves that elucidate material responses to compressive forces and highlight variations in load-bearing capacities. The study explores diverse failure modes, attributing them to stress concentration at geometric transitions and contact regions. Stress–strain curves contribute valuable insights into material characteristics, with ultimate stress values as crucial indicators of resistance to deformation and rupture. The FE analysis simulation results visualise deformation patterns and stress concentration zones. The findings illustrate that the highest stress concentration areas exist in the internal boundary of hot water bottles near the neck and cap region. This is experimentally confirmed through the bursting failures of four samples, with three failures occurring in this specific region. The findings support the guidance that users should avoid sleeping with a hot water bottle as it may fail under compression if they lay on top of it. Meanwhile, this result guides manufacturers to strengthen the weak areas of hot water bottles around the nicks and edges. This study significantly enhances our understanding of hot water bottle mechanics, thereby guiding design practice to improve overall performance and user safety. In summary, hot water bottles are commonly used but have not been investigated scientifically regarding external loading conditions and their related failure, as the current study has achieved. Identifying the weak points through experiment and simulation directs manufacturers towards required improvements in particular regions, such as the bottleneck and edge reinforcement during the design and manufacturing phases.

Integrated analysis of blood DNA methylation, genetic variants, circulating proteins, microRNAs, and kidney failure in type 1 diabetes.

Variation in DNA methylation (DNAmet) in white blood cells and other cells/tissues has been implicated in the etiology of progressive diabetic kidney disease (DKD). However, the specific mechanisms linking DNAmet variation in blood cells with risk of kidney failure (KF) and utility of measuring blood cell DNAmet in personalized medicine are not clear. We measured blood cell DNAmet in 277 individuals with type 1 diabetes and DKD using Illumina EPIC arrays; 51% of the cohort developed KF during 7 to 20 years of follow-up. Our epigenome-wide analysis identified DNAmet at 17 CpGs (5'-cytosine-phosphate-guanine-3' loci) associated with risk of KF independent of major clinical risk factors. DNAmet at these KF-associated CpGs remained stable over a median period of 4.7 years. Furthermore, DNAmet variations at seven KF-associated CpGs were strongly associated with multiple genetic variants at seven genomic regions, suggesting a strong genetic influence on DNAmet. The effects of DNAmet variations at the KF-associated CpGs on risk of KF were partially mediated by multiple KF-associated circulating proteins and KF-associated circulating miRNAs. A prediction model for risk of KF was developed by adding blood cell DNAmet at eight selected KF-associated CpGs to the clinical model. This updated model significantly improved prediction performance (c-statistic = 0.93) versus the clinical model (c-statistic = 0.85) at P = 6.62 × 10-14. In conclusion, our multiomics study provides insights into mechanisms through which variation of DNAmet may affect KF development and shows that blood cell DNAmet at certain CpGs can improve risk prediction for KF in T1D.

Shear failure analysis of UHPC-NC composites interface with U-shaped studs

Given the extensive utilization of composite structures of ultra-high performance concrete (UHPC) and normal concrete (NC) in engineering applications, there has been a growing emphasis on studying the shear failure and mechanical properties analysis of the UHPC-NC interface. U-shaped studs assume a crucial role in reinforcing the UHPC-NC interface. A three-dimensional finite element model was constructed with different parameters to investigate the shear failure and mechanical properties of UHPC-NC incorporating U-shaped studs. The failure mode and the influences of diameter, internal span, stud number and concrete compressive strength on the shear characteristics of the UHPC-NC interface were analyzed. The numerical analysis indicates the final failure mode of the UHPC-NC interface with U-shaped stubs is the fracture of the U-shaped stud. The diameter and internal span of studs influence the interface shear capacity, while interface shear capacity is not sensitive to the compressive strength of UHPC and NC. Moreover, a calculation formula for the shear capacity of the UHPC-NC interface with U-shaped studs was proposed, considering the influence of stud diameter and internal span. An exponential function is recommended for predicting the interface shear slip and the stiffness corresponding to 0.55 times the shear capacity is adopted as the elastic shear stiffness. The interface shear slip model and the expression for elastic shear stiffness were established, providing a reference for approximate calculation without experimental data.

Enhancing geomechanical characteristics of calcium sulfoaluminate (CSA) cement-treated soil under low confining pressures

This study examines the efficacy of employing calcium sulfoaluminate (CSA) cement, an environmentally friendly binder, for enhancing the geomechanical characteristics of sand, particularly under low confining pressure conditions. A series of triaxial consolidated drained tests were performed on sand samples treated with varying content (5, 7, and 10%) of CSA cement and 10% ordinary Portland cement (OPC) under various low confining pressures (50, 100, 200, and 400 kPa). The test findings demonstrated the importance of cement content and confining pressure on the mode of failure, stress–strain and volumetric behavior, failure characteristics, and shear strength parameters of the treated quartz sand. After a curing period of 14 days, samples treated with 10% CSA cement exhibited a remarkable 212% increase in peak deviator stress and an 89% reduction in axial strain at failure, indicating higher initial stiffness compared to untreated samples under a 400 kPa confining pressure. Furthermore, the samples treated with 10% CSA exhibited higher peak deviator stress, initial stiffness, and strength development compared to those treated with 10% OPC. The scanning electron microscopy analysis provides insights into particle breakage and bond degradation processes, which increase with confining pressure in CSA-treated samples. Also, the mode of failure analysis reveals a transition from ductile to slightly brittle behavior with increasing cement content. Notably, the geomechanical properties of the treated material emphasized the significant impact of CSA cement on soil improvement. Thus offering a sustainable alternative for soil improvement in construction projects.

Influence of different manufacturing techniques on GFRP flat-joggle-flat composite joints using multi-scale reinforcements for enhancing shear properties

Abstract Composite materials, particular glass fibre-reinforced polymers, or GFRP are being used far more frequently. Airframes have been manufactured utilizing reinforced composites, including struts, frames, and flaps, employing raised epoxy-based co-cure technology. The current research describes a multi-scale approach to fortifying graphene nanoparticles (GNP) and carbon fibre Z-pins in order to strengthen the flat-joggle-flat composite joints with different manufacturing technique. Shear investigation showed that adding GNPs and putting carbon fibre pins (Z-pins) in a crosswise position (perpendicular to plane) to the joints surface, concurrent reinforcement gives rise to greater shear characteristics with quasi-static loads. Specifically, there was a 45.6 % improvement in shear resistance when contrasted with unreinforced co-cured FJF joints. The FESEM has been utilised to demonstrate the failure analysis of the specimens, which shows the clear failure mechanism of the FJF joint specimens. The FJF joint with multiscale reinforcement has a very high natural frequency of 685.1 Hz as compared to other configurations, according to the vibration analysis.

In-plane compressive properties and failure mechanisms of gradient Cf/ZrB2–SiC composites in high-temperature environment

The gradient Cf/ZrB2–SiC composites can exert the dual advantages of low-density and excellent heat resistance, but which have the complex mechanical properties due to the inhomogeneous geometry characteristics. The in-plane compressive behavior and failure analysis can examine the material integrity and the effect of inhomogeneous characteristics. The in-plane compressive elastic modulus distribution is expressed mathematically by using the superficial elastic modulus, back elastic modulus, and the gradient pore distribution. The superficial elastic modulus and the gradient pore distribution of the gradient materials were characterized by nanoindentation test and Micro-CT statistics. The back of the gradient materials is the porosity needled C/C composites without introducing ZrB2–SiC matrix, whose elastic modulus can be referenced from our previous work. The in-plane compressive experiments of the gradient materials in the high-temperature environment were also conducted to study the failure mechanisms. The strength of the gradient materials is further revealed by the temperature-dependent properties of carbon fibers and thermal residual stress release. The results indicate the gradient structure can effectively eliminate the delamination damage, but the high temperature drastically weakens the ability of needled fibers suppressing delamination damage in the high-porosity region of the gradient materials. This study can be helpful to the material design and evaluation of mechanical properties for the gradient Cf/ZrB2–SiC composites.

Prediction and analysis of flexural stiffness for 3D-printed continuous fiber–reinforced composites with different matrix fill ratios and layer orders

Bending load is often encountered in engineering applications, but it is less studied for 3D-printed continuous fibre–reinforced composites (CFRC). We present the flexural properties of 3D-printed composites as a function of layer order and matrix fill ratio. We applied Classic Laminate Theory to estimate the flexural modulus and showed that the Kerner-Hashin model is suitable for taking voids into account when calculating the elastic properties of the matrix layer. Using optical microscopic analysis, we identified the main defect sources of 3D-printed CFRC structures, such as voids, fibre waviness, fragmentation and poor bonding between laminas. By performing failure analysis based on the Fibre Bundle Cell method, we found that the use of top/bottom-type reinforcement instead of alternating layering will increase the reliability of the 3D-printed composites under bending load. Furthermore, the failure process will be more gradual and cover higher load levels, which increases safety.

Boundary element method: cells with embedded discontinuity modeling the fracture process zone in 3D failure analysis

Boundary element method: cells with embedded discontinuity modeling the fracture process zone in 3D failure analysis

Laser treated novel textures for adhesion performance of aluminum alloy joints exposed to corrosion

The aim of this study was to investigate novel laser-treated structures designed to improve the adhesion performance and corrosion resistance of AA7075-T6 bonded joints. The spacing, position, and surface area parameters of the laser-treated grooves were investigated to understand their role in adhesion performance even under corrosion conditions. Laser-treated surfaces were analyzed using microscopic, topographic, and chemical methods to determine their scientific contribution to adhesion and corrosion performance. Laser-treated adherends were also bonded to mechanically test their bond strength both before and after exposure to corrosion for varying periods of time. Roughness and therefore surface area have a significant effect on adhesion performance; however, it is worth noting that the best adhesion performance both before and after corrosion exposure was achieved when the required surface area was properly designed and, laser treated according to the salt water exposure directions to inhibit its diffusion into the adhesion interface. The performance of the novel laser-treated structures in terms of adhesion performance under corrosive atmosphere was also supported by failure analysis. The mixed failure mode was significantly shifted to the cohesive failure mode, especially for bonded joints with box-type laser-treated structures.

Study on Fracture Characteristics of Layered Sandstone under Asymmetric Loading.

In engineering practice, layered rock masses often display obvious anisotropy while deforming and failing, and the failure mode directly impacts the engineering construction stability. In this study, the fracture failure load, fracture toughness, crack deflection angle, and failure mode of a layered rock mass under different fracture modes were analyzed by utilizing improved asymmetric semi-circular disc specimens. According to the constitutive model of transversely isotropic materials, the maximum tensile stress (MTS), maximum energy release rate (MERR), and maximum strain energy density (MSED) calculation formulas were modified, and the calculation formulas of the three prediction criteria under anisotropic materials were derived. The calculation results were compared with the experimental results. The results show that the fracture toughness and crack deflection angle were significantly affected by the weak bedding plane. As a result of applying the MTS criterion, the results are closer to the experimental results, providing a solid foundation for engineering deformation, failure, and fracture analyses.