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To investigate the failure of the steering tie rods and steering knuckle arms of a heavy semi-trailer tractor during accelerated life testing in a proving ground, detailed detections were performed on the material structural properties and machining accuracy of the failed components. Using the Neuber’s rule and cyclic hysteresis loop equation, the measured nominal stress was transformed into the local stress-strain cycles. The fatigue damage of the fracture components was calculated using the Morrow’s mean stress correction model. The findings from the detections and calculations indicate that the material properties are in compliance with designed technical specifications. The steering tie rods exhibited buckling deformation after becoming unstable due to its high flexibility and thin rod structure, which induced cyclic dynamic additional bending moments, identified as the primary cause of its fracture. The fracture surfaces and crack origins of the steering knuckle arms displayed clear machining tool marks, the conicity and surface roughness did not meet the design specification precision, and the assembly contact area with the steering knuckles was only approximately 20%–30%. This insufficient contact resulted in localized high stress concentrations at the root of the cone body, leading to low-cycle bending fatigue fractures.

The fractured coiled tubing of TS90 steel grade Φ50.8 mm ×3.96 mm in a certain oilfield was analyzed through macroscopic observation, magnetic powder inspection, physical and chemical properties testing, microstructure analysis and SEM analysis. The results showed that the coiled tubing fracture belonged to fatigue fracture and the fatigue crack originated from the area of cyclic friction on the outer surface of the tubing. The cyclic axial plastic stress of the tubing in service caused micro-cracks in the source area and finally led to fatigue fracture failure of the tubing.

A systematic and comprehensive analysis of the hot deformation and mechanisms of SiC particle-reinforced aluminum matrix composites is significant for optimizing the processing of the composites and obtaining the desired components. Based on this, related research on 11 vol% SiCp particle-reinforced 7050Al matrix composites was carried out. Hot compression experiments were carried out on the Gleeble-3500 thermal simulator to study the hot deformation behavior of composites at the temperature of 370–520 °C and strain rate of 0.001–10 s−1. The hyperbolic sine constitutive equation of the material was established, and the processing map was calculated. Combining the typical metallograph and misorientation angle distribution, the microstructure evolution mechanism of composites was analyzed, and the effect of particles on recrystallization behavior was investigated. Under certain process conditions, the dominant deformation mechanism of composites changed from dynamic recovery (DRV) to dynamic recrystallization (DRX), and the grain boundary sliding mechanism began to play a role. In addition, high temperature tensile and elongation at break were tested, and it was found that the dominant form of fracture failure changed from brittle fracture of the particles to ductile fracture of the matrix as the temperature increased.

With the development of the rail transit industry, more attention has been paid to the passive safety of rail vehicles. Structural damage is one of the main failure behaviors in a rail vehicle collision, but it has been paid little attention to in past research. In this paper, the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out. The mechanical fracture properties of this material were studied, and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness. Through the tests, the fracture behavior of materials with wide stress triaxiality was obtained, and each specimen's fracture locations and fracture strains were determined. Parameters of a generalized incremental stress state dependent damage model (GISSMO) of the material were calibrated, and the model's accuracy was verified with test results from a 45° shear specimen. The GISSMO failure model accurately reflected the fracture characteristics of the material. The mesh dependency of this model was modified and discussed. The results show that the simulation agrees well with experimental data for the force-displacement curve after correction, but the strain distribution needs to be further studied and improved.

The instability of mine roadways is significantly influenced by the coupled effects of groundwater seepage and non-uniform loading. These interactions often induce localized plastic deformation and progressive failure, particularly in the roof and sidewall regions. Seepage elevates pore water pressure and deteriorates the mechanical properties of the rock mass, while non-uniform loading leads to stress concentration. The combined effect facilitates the propagation of microcracks and the formation of shear zones, ultimately resulting in localized instability. This initial damage disrupts the mechanical equilibrium and can evolve into severe geohazards, including roof collapse, water inrush, and rockburst. Therefore, understanding the damage and failure mechanisms of mine roadways at the mesoscale, under the combined influence of stress heterogeneity and hydraulic weakening, is of critical importance based on laboratory experiments and numerical simulations. However, the large scale of in situ roadway structures imposes significant constraints on full-scale physical modeling due to limitations in laboratory space and loading capacity. To address these challenges, a straight-wall circular arch roadway was adopted as the geometric prototype, with a total height of 4 m (2 m for the straight wall and 2 m for the arch), a base width of 4 m, and an arch radius of 2 m. Scaled physical models were fabricated based on geometric similarity principles, using defect-bearing sandstone specimens with dimensions of 100 mm × 30 mm × 100 mm (length × width × height) and pore-type defects measuring 40 mm × 20 mm × 20 mm (base × wall height × arch radius), to replicate the stress distribution and deformation behavior of the prototype. Uniaxial compression tests on water-saturated sandstone specimens were performed using a TAW-2000 electro-hydraulic servo testing system. The failure process was continuously monitored through acoustic emission (AE) techniques and static strain acquisition systems. Concurrently, FLAC3D 6.0 numerical simulations were employed to analyze the evolution of internal stress fields and the spatial distribution of plastic zones in saturated sandstone containing pore defects. Experimental results indicate that under non-uniform loading, the stress–strain curves of saturated sandstone with pore-type defects typically exhibit four distinct deformation stages. The extent of crack initiation, propagation, and coalescence is strongly correlated with the magnitude and heterogeneity of localized stress concentrations. AE parameters, including ringing counts and peak frequencies, reveal pronounced spatial partitioning. The internal stress field exhibits an overall banded pattern, with localized variations induced by stress anisotropy. Numerical simulation results further show that shear failure zones tend to cluster regionally, while tensile failure zones are more evenly distributed. Additionally, the stress field configuration at the specimen crown significantly influences the dispersion characteristics of the stress–strain response. These findings offer valuable theoretical insights and practical guidance for surrounding rock control, early warning systems, and reinforcement strategies in water-infiltrated mine roadways subjected to non-uniform loading conditions.

Based on the inclusion theory, the calculation formula of additional water pressure caused by the change of external stress state of fracture water in rock-mass is deduced, and its rationality and correctness are verified by numerical experiments. Then, using the rock fracture process analysis system RFPA2D-flow and considering the influence of additional water pressure, the fracture failure process of rock-mass with multiple (2, 3 and 4 fractures) nonparallel fractures (dip angles are not repeatedly selected from 0°, 30°, 45°, 60° and 90°) under the coupling action of stress and seepage is numerically simulated, and the following conclusions are obtained: (1) for rock-mass with two nonparallel fractures, large deformation and failure occur at the fracture position with an inclination of 0° because the fracture strike is perpendicular to the loading direction; In addition, the rock-mass first breaks at the fracture position with low strength, and gradually develops into overall failure, while the other fracture position is relatively complete. (2) For the rock-mass with 3 and 4 nonparallel fractures, similar to the rock-mass with 2 nonparallel fractures, the fracture failure of the rock-mass mainly occurs at the fracture position with low strength, the difference is that the number of fractures is more, and the rock bridge between fractures is connected, and the failure range is larger. (3) For the strength of fractured rock-mass, the fracture strength of rock-mass with multiple nonparallel fractures decreases gradually with the increase of fracture density.

During the long-term service of a metro vehicle, different kinds of fracture failure occur on the bogie, with the axle-box hanger being a representative one. To investigate the cause of the hanger structure failure, a study was conducted that combined field investigation with finite element analysis, focusing on the modal resonance behavior between the hanger and the rail corrugation. Based on the findings, a structural optimization of the hanger was proposed and an experimental verification was conducted. The results show that the main reason for the hanger fracture failure is that the resonance phenomenon that occurred in the hanger structural modal frequency when exposed to the rail corrugation, leading to the poor lateral vibration environment of the hanger and the fracture failure in the long-term service operation. The first-order structural modal frequency of the hanger is 432 Hz, which is very close to the wheel/rail excitation frequency of 435 Hz caused by the rail corrugation. The modal frequency of three newly designed hangers can prevent the frequency caused by the rail corrugation. Experimental verification of the new hangers showed a 55.49% lower maximum average acceleration of hanger lateral vibration compared to the original structure, confirming the effectiveness of the redesigned hangers.

The superheater and re-heater piping components in supercritical thermal power units are prone to creep and fatigue failure fracture after extensive use due to the high pressure and temperature environment. Therefore, safety assessment for superheaters and re-heaters in such an environment is critical. However, the actual service operation data is frequently insufficient, resulting in low accuracy of the safety assessment. Based on such problems, in order to address the issues of susceptibility of superheater and re-heater piping components to creep, inaccurate fatigue failure fracture, and creep–fatigue coupling rupture in a safety assessment, their remaining life prediction and reliability, as well as the lack of actual service operation data, multisource heterogeneous data generated from actual service of power plants combined with deep learning technology was used in this paper. As such, three real-time operating conditions’ data (temperature, pressure, and stress amplitude) during equipment operation are predicted by training a deep learning architecture long short-term memory (LSTM) neural network suitable for processing time-series data and a backpropagation through time (BPTT) algorithm is used to optimize the model and compared with the actual physical model. Damage assessment and life prediction of final superheater tubes of power station boilers are carried out. The Weibull distribution model is used to obtain the trend of cumulative failure risk change and assess and predict the safety condition of the overall system of pressurized components of power station boilers.

The problems of large deformations, failures, and fractures that agricultural tillage tools may encounter during the cultivation process has long been a concern in the field of agricultural machinery design and manufacturing. It is important to establish a more accurate numerical model to effectively predict tools’ plastic deformation failures and ductile fracture failures. This research develops a numerical model for predicting the plastic deformation failure and ductile fracture failure of agricultural tillage tools using the smoothed particle hydrodynamics (SPH) method and the Johnson–Cook constitutive model. The model uses the Drucker–Prager criterion to describe the elastic–plastic constitutive behavior of the soil, the von Mises criterion to describe the Johnson–Cook constitutive model of the tool, and the coupling condition with the Lennard-Jones repulsive force to describe the interaction between the tool and soil. The numerical results show that the proposed model can effectively simulate the interaction between the tool and soil, as well as the tool’s plastic deformation failure and ductile fracture failure during the agricultural cultivation process. It can also predict the variation trend of the cutting force of the tool. This helps to provide a new approach for the numerical simulation of such problems.

Phyllite, characterized by well-developed foliation, is a low-grade metamorphic rock. This study offers a comprehensive investigation into its failure patterns and micro-fracture classifications when subjected to Brazilian splitting tests, combining experimental observations and numerical simulations. The analysis includes interpreting AE signals in various contexts, highlighting two distinct failure modes based on the foliation-loading angles, and revealing the emergence of an M-shaped brittleness tendency as θ increases. Micro-crack classification is achieved through frequency band and spectrum analysis, culminating in deriving the formula A F = 116.565 × R A + 80.146 , which furnishes a detailed understanding of crack development. Utilizing the PFC3D software, sensitivity analyses are conducted to investigate the influence of joint parameters on failure strengths, damage patterns, and micro-crack progression within this transverse isotropy rock. Key findings include the observation that shear strength enhancement tends to shift the rock from a layer-activated fracture pattern to mixed and central damage patterns and amplifies the impact of θ at larger angular intervals on failure strength. Stiffness strengthening is found to significantly inhibit rock matrix cracking, particularly at smaller foliation-loading angles, while the influence of friction coefficients is deemed negligible. These insights into Phyllite damage mechanisms and behaviors contribute to the design and assessment of structures in stratified strata, offering valuable guidance for enhancing stability and safety.