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To reduce the clamping damage caused by robotic manipulators during the harvesting of blood oranges, this study investigated the mechanical response of blood oranges when in contact with curved surfaces of different curvatures. A three-dimensional model of a blood orange was established using reverse engineering technology, and its physical properties were measured. A peel-pulp composite finite element model was constructed to simulate the uniaxial static compression test and the contact process of blood oranges clamped by curved surfaces of varying curvatures. The results indicated that the maximum error in the uniaxial static compression test was 6.8%, confirming the accuracy of the model. In the simulations of the curved surface clamping tests, the stress at the contact point between the blood orange and the curved surface was highest, with the pulp being damaged before the peel. A comparison of the effects of different curved surfaces on the stress and deformation of the blood orange revealed that, under the same clamping force, the 46 mm radius curved surface resulted in lower stress and smaller deformation in the various parts of the blood orange compared to the other curvatures. When a clamping force of 40 N was applied, the bruise volumes caused by the 44, 46, 48, and 50 mm radius curved surfaces were 3897.11, 1193.93, 10553.72, and 21889.74 mm³, respectively. Therefore, the 46 mm radius curved surface posed the lowest risk of mechanical damage to the blood orange. This study provides a reference for the micromechanical research of citrus fruits and offers a basis for the design of end-effector harvesting devices. [ABSTRACT FROM AUTHOR]

Purpose: Ball grid array (BGA) package is prone to failure issues in a thermal vibration-coupled environment, such as deformation and fracture of solder joints. To predict the minimum equivalent stress of solder joints more accurately and optimize the solder joint structure, this paper aims to compare the machine learning method with response surface methodology (RSM). Design/methodology/approach: This paper introduced a machine learning algorithm using Grey Wolf Optimization (GWO) Support Vector Regression (SVR) to optimize solder joint parameters. The solder joint height, spacing, solder pad diameter and thickness were the design variables, and minimizing the equivalent stress of solder joint was the optimization objective. The three dimensional finite element model of the printed circuit board assembly was verified by a modal experiment, and simulations were conducted for 25 groups of models with different parameter combinations. The simulation results were employed to train GWO-SVR to build a mathematical model and were analyzed using RSM to obtain a regression equation. Finally, GWO optimized these two methods. Findings: The results show that the optimization results of GWO-SVR are closer to the simulation results than those of RSM. The minimum equivalent stress is decreased by 8.528% that of the original solution. Originality/value: This study demonstrates that GWO-SVR is more precise and effective than RSM in optimizing the design of solder joints. [ABSTRACT FROM AUTHOR]

The structural safety and sealing performance of a triple-eccentric butterfly valve are crucial technical indicators that influence its reliability and service life. In this study, a new multi-objective optimization strategy is proposed to realize a lightweight design of valve trims, reduce the maximum equivalent stress, and reasonably distribute the sealing-specific pressure. A two-stage optimization scheme is designed by combining topology optimization (TO) and response surface methodology optimization (RSM). The topology optimization is employed to allocate the material distribution of the valve trims and provide the parameters for the response surface optimization, while the response surface methodology optimization conducts a further revision and optimization of the structural parameters of the valve trims. The results of the simulation experiments indicate that the maximum equivalent stress of the lightweight designed valve trims is reduced from 290.85 MPa to 99.88 MPa, and the maximum sealing-specific pressure of the sealing surface is reduced from 197.78 MPa to 77.83 MPa. Additionally, a novel approach is presented for assessing the sealing performance using the clearance of the fitting surface. This method can intuitively evaluate the state of metal sealing and guide the design of the fitting tolerance by analyzing the sensitivity of the dimensional deviation to the sealing-specific pressure. The findings demonstrate that the optimized valve exhibits good structural safety and sealing performance. • A new multi-objective optimization strategy is proposed to improve the structural safety and sealing performance of valves. • A new method is proposed to evaluate the sealing performance using the clearance of the fitting surface. • The maximum equivalent stress and sealing-specific pressure could evaluate the structural safety and sealing performance of triple-eccentric butterfly valve. • The sensitivity analysis of the limit deviations was utilized to guide the design of the assembly tolerance. [ABSTRACT FROM AUTHOR]

Copyright of Energy Chemical Industry is the property of Energy Chemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Post and core restoration is a common choice for tooth defects, but the repair effects of various post and core materials are different. OBJECTIVE: To evaluate the stress distribution at the post and core, tooth root, and bonding agent site of post and core models made of different elastic modulus post and core materials using finite element method. METHODS: A three-dimensional root canal treated maxillary central incisor model was built using three-dimensional modeling software, which was restored with a full ceramic crown. The post and core materials in the restoration used nanoceramic resin (elastic modulus=12.8 GPa), composite resin (elastic modulus=16 GPa), hybrid ceramic (elastic modulus=34.7 GPa), glass ceramic (elastic modulus=95 GPa), titanium alloy (elastic modulus=112 GPa), and zirconia (elastic modulus=209.3 GPa). The model was fixed in cortical bone. A 100 N concentrated force of 45° from the long axis of the tooth was applied to 1/3 of the crown and tongue side of the central incisor. The stress distribution of the post and core, dentin, and tooth-root bonding agent in the model was repaired by the maximum principal stress criterion. RESULTS AND CONCLUSION: (1) When the post and core materials with higher elastic modulus was used, the post-core stress in the repair model was more concentrated. When the elastic modulus of the post and core materials (nanoceramic resin and composite resin) was close to dentin, the stress distribution of the post and core was more uniform. The stress distribution of dentin in all restoration models was similar regardless of post and core materials. When the post and core with higher elastic modulus was used, more stress concentration was shown at the post and root bonding agent in the repair model. (2) The maximum stress values at the post and core, tooth root, and the bonding agent site of post and tooth root in the nanoceramic resin model were 31.00, 33.21, and 0.51 MPa, respectively. The maximum stress values at the post and core, tooth root, and the bonding agent between the post and tooth root in the composite resin model were 36.84, 33.14, and 0.59 MPa, respectively. In the mixed ceramic model, the maximum stress values at the post and core, tooth root, and the bonding agent between the post and tooth root were 64.05, 32.83, and 1.00 MPa, respectively. In the glass ceramic model, the maximum stress values at the post and core, tooth root, and the bonding agent between the post and tooth root were 112.30, 32.69, and 1.73 MPa, respectively. In the titanium alloy model, the maximum stress values of the post and core, tooth root, and the bonding agent between the post and tooth root were 120.00, 32.17, and 1.86 MPa, respectively. In the zirconia model, the maximum stress values of the post and core, tooth root, and the bonding agent between the post and tooth root were 148.80, 31.85, and 2.28 MPa, respectively. (3) The higher the elastic modulus of the post and core material, the higher the maximum stress at the post and core during restoration. The elastic modulus of the post and core material had no significant effect on the maximum stress of the dental bonding agent and dentin. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To compare and analyze the mechanical stability of various internal fixations applied to femoral intertrochanteric fracture A031-A2.1 by finite element method. METHODS: Based on the validated finite element model of femur (Intact), the model was cut and made into A031-A2.1 intertrochanteric fracture of femur. Different internal fixation systems were implanted by simulating clinical operation methods, and fixation models of proximal femoral nail antirotation, dynamic hip screw, percutaneous compression plate and proximal femoral locking plate were established respectively. All nodes under the distal femur of the four groups of models were constrained, and compression loads of 700, 1 400 and 2 100 N were applied to the femoral head. Von Mises stress distribution and compression stiffness of each group of models were observed through calculation and analysis, and mechanical stability of each group was compared. RESULTS AND CONCLUSION: (1) Through calculation and analysis, after calculating the compression stiffness by comparing the deformation of each model, the compression stiffness of each model under various loads showed the trend: physiological group > proximal femoral nail antirotation group > proximal femoral locking plate group > percutaneous compression plate group > dynamic hip screw group. The compressive stiffness of the complete physiological group model was significantly higher than that of all surgical group models. (2) The stress index was observed. Due to the stress shielding effect, the stress peak value of each fixed group was higher than that of physiological group, and the maximum peak value was concentrated on each internal fixation. Proximal femoral nail antirotation group had the smallest stress peak, while dynamic hip screw group had the highest stress. The stress distribution trend showed physiological group < proximal femoral nail antirotation group < percutaneous compression plate group < proximal femoral locking plate group < dynamic hip screw group. (3) The stress distribution in the bone model showed different results depending on the implantation location of internal fixation. (4) It is concluded that for intertrochanteric fracture of femur, all kinds of internal fixation can effectively fix it. Combined with the results of finite element analysis, proximal femoral nail antirotation group is a better internal fixation choice, showing the characteristics of small deformation, low stress peak, and uniform stress distribution. The mechanical effect of percutaneous compression plate group and proximal femoral locking plate group is excellent, and the fixation effect is close to proximal femoral nail antirotation fixation. The fixation effect of dynamic hip screw is not good, and the mechanical stability of this group is poor compared with other internal fixation. [ABSTRACT FROM AUTHOR]

This study reports on the design optimisation of the swinging jaw crusher plate. Jaw crusher machines are used in the mining and construction industry for crushing rocks and mineral ores to the appropriate sizes for direct application or further processing. During the crushing process, large and non-evenly distributed impact forces occur, resulting from uneven feed patterns and nonhomogeneous material composition (varying hardness). Hence, the jaw plate experiences inhomogeneous stress distributions causing warping and fracture failure of the crusher plates. The plate warping reduces the crusher performance, resulting in low crusher efficiency, high cost of replacing the crushing plates, and higher energy consumption. In this study, the design parameters: plate profile, thickness, and the height of the jaw plate were optimised using ANSYS software. These design parameters were varied to analyse deformation and stress distribution during crushing. Design of experiment techniques was used to determine the optimal design parameters. Optimisation results showed that the optimal design parameters were: 40.06 mm thickness, 4.94 mm plate profile, and 996.21 mm height. An analysis using the optimal parameters produced the optimal outputs as 1.41 MPa for the maximum equivalent stress and 2.7 × 10–8 m for the average total deformation. This study shows that the jaw crusher plate geometry influences the flow stress and deformation behaviour during the crushing process. The findings from this study provide the basis for future designs of swing jaw crushers for industrial applications. [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In response to the challenges posed by long-term cyclic loading and unloading in underground rock engineering, this study systematically investigates the macro- and meso-mechanical response mechanisms of fractured rock masses under cyclic loading conditions. We performed graded cyclic loading–unloading tests on parallel double-fractured sandstone samples with varying spatial distribution configurations. These tests were integrated with digital image correlation (DIC) technology, fractal dimension analysis, and discrete element method (DEM) numerical simulations to analyze the mechanical properties, deformation characteristics, crack propagation features, and meso-fracture mechanisms of the fractured rock masses. The findings indicate that the diverse spatial distribution characteristics of the double fractures exert a significant influence on the loading–unloading processes, surface deformation fields, and fracture states of the rock. Cyclic loading leads to an increase in the fractal dimension of the fractured samples, resulting in more intricate and chaotic crack propagation patterns. Furthermore, DEM simulations reveal the impact of fracture spatial configurations on the force chain distribution within the rock bridges. The equivalent stress nephogram effectively represents the stress field distribution. This offers valuable insights for predicting meso-fracture trends in rocks. This paper comprehensively integrates both experimental and numerical simulation methodologies to deliver a thorough analysis of the complex mechanical behavior of fractured rock masses under cyclic loading conditions, with direct relevance to engineering applications such as mine excavation and slope stabilization. [ABSTRACT FROM AUTHOR]

This paper proposes a new concept of material effort that considers heat-induced plasticity for heat-resistant steels. These steels indicate a strength differential effect, a stress shearness effect, pressure sensitivity, and other features. Therefore, a three-parameter, temperature-dependent yield function was presented and, next, analytically and geometrically researched. To validate the accuracy of the formulated yield function, experiments were conducted with the designed specimens to characterize the heat-resistant steels St12T and 26H2MF, which underwent simple shear, uniaxial strain tension, and compression tests. The yield function was calibrated by using a simple analysis. Next, the calibrated constitutive equations were used to numerically determine the load–stroke responses of different tests. The numerical analysis showed that the proposed yield function based on three parameters could accurately describe the thermal effort in various loading conditions from the onset of yielding to the ultimate rupture. Accordingly, the proposed yield function is recommended to model material strength under various thermal loading conditions. [ABSTRACT FROM AUTHOR]

The article combines issues related to biaxial fatigue loading, corrections for equivalent stress calculations, and the practical application of new knowledge regarding biaxial fatigue in the aviation industry. It considers the possibility and expediency of taking into account the anisotropy of metals' mechanical characteristics in aircraft repair procedures, such as patching and replacing damaged skin panels. The biaxial loading of the skin is shown to be a significant factor that should be considered in the aircraft skin repair process. It is shown that while well-known Huber-Mises formula works well for isotropic materials, the fuselage skin made of anisotropic alloys requires corrections to the Huber-Mises method. For aircraft parts subjected to biaxial loading, the assessment of equivalent uniaxial stresses can be done by introducing the crystallographic factor into the Huber-Mises formula. This is achieved by transforming the biaxial stress components of fuselage loading due to pressurization and bending into the resolved stresses in the activated crystallographic slip systems of the dominant texture. [ABSTRACT FROM AUTHOR]

As the important equipment in the field of well control, the conical blowout preventer can quickly close the wellhead when a blowout accident occurs. In this paper, the conical blowout preventer of FH28-35 is taken as the research objects, and the maximum stroke of the conical blowout preventer are calculated by geometric methods. Based on the theoretical analysis and experimental data, the mechanical behavior of the conical blowout preventer during well sealing was analyzed, the equivalent stress and contact pressure distribution law of the rubber core were summarized. The finite element model of the conical blowout preventer was established based on the polynomial regression analysis, the simulation results were input into the Design-Expert software, and the residual analysis was carried out. Finally, the optimal combination of the three response factors was analyzed. The results show that the equivalent stress of the core of the conical blowout preventer is reduced when the core is optimized without affecting the sealing effect, which can effectively prolong the life of the core. [ABSTRACT FROM AUTHOR]

The discussed research combine two components: a) the improvement of the current procedure for stress-strain analysis of aircraft parts on the basis of the introduction of a crystallographic factor into the Huber-Mises-Hencky equivalent-stresses' calculation procedure; b) an example of application of this new calculation procedure into the practice of repairing aircraft skin that has been damaged by shooting, fatigue, corrosion, or firing. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Mechanics is the property of Chinese Journal of Applied Mechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study highlights the development of an intelligent thermo-structural model for precise prediction of responses such as the width of heat-affected zone (HAZ), equivalent stress and total deformation for laser beam machining (LBM) process while machining a novel Dual Phase 780 (DP780) workpiece. The numerical model is analyzed through response surface Box–Behnken design to study the consequences of input parameters such as voltage (V), current (I) and cutting speed (N) on the above-mentioned response parameters. The results achieved through the numerical model are validated by comparing them with experimental results. Furthermore, a careful parametric study along with line and surface plot analysis is conducted to evaluate both linear and quadratic relationships between the input and the response parameters, respectively. The results indicate that the HAZ can be reduced significantly through efficient laser processing with optimum input parameters. The process parameters are optimized by developing an objective function for each of the response parameters through regression analysis. An extremum model is used to obtain the ideal values of HAZ, equivalent stress and total deformation. These results are also validated by conducting a confirmative test using the numerical simulation model which is validated through experiments. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The paper involves reviewing researches, which consider crystallographic aspects of fatigue damage in both metallic polycrystals and single crystals. The primary aim of this work is to substantiate the necessity and feasibility of considering both material texture in polycrystals and the crystallographic orientation of single crystals during the assessment of equivalent stresses under multiaxial loading. Additionally, the study aims to assess quantitatively the accumulated fatigue damage. The tasks undertaken include as follow: analysing contemporary research investigating cases, where surface deformation relief in metals serves as an indicator of accumulated fatigue damage, examining crystallography; studying the surface relief components, and estimating how the texture of constructional metals influences the formation of deformation relief and corresponding fatigue damage. The study provides evidence for the activation of additional slip systems during biaxial loading. It is noted that the Huber--Mises method for assessing equivalent stresses during biaxial loading does not account for anisotropy in constructional materials, such as aluminium alloys commonly used in aviation. Methodologically, the paper considers mechanical tests, light microscopy, x-ray analysis. The main result of the study is the substantiation of the need to consider metals' crystallographic anisotropy, when calculating equivalent stresses under multiaxial loading. The review of research indicates that the fatigue- damage accumulation and the evolution of surface deformation relief are related closely to the crystallographic orientation of single crystals and crystallites in textured polycrystal materials. Recognizing these crystallographic aspects is essential for thorough estimating accumulated fatigue damage. It demonstrates the necessity and feasibility of considering crystallographic aspects in the development of methods for estimating accumulated fatigue damage. The effect of both the crystallographic orientation of single crystals and the texture of polycrystalline material is pronounced under the uniaxial and biaxial loadings. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: For teeth with normal dental crown height, pulp cavity retention crown restoration with different depths of the pulp cavity and different repair materials affects the stress and flexural strength of tooth tissue. For short crown molar defects, the research on pulp cavity repair mainly focuses on clinical observation and in vitro flexural strength experiments. OBJECTIVE: To establish a three-dimensional finite element model for short crown molar restored by the endocrown after root canal treatment to analyze the effects of different pulp cavity retention depths and different repair materials on the distribution and size of dentin equivalent stress. METHODS: Based on establishing the complete model of the short crown mandible first molar, a three-dimensional finite element model was established for repairing the distal adjacent defect of the short crown molar with different pulp cavity retention depths (h=2, 3, 4 mm) and different repair materials (zirconia, lithium disilicate). Under the oblique loading, the equivalent stress distribution was observed. The peak value of dentin equivalent stress and the mean value of equivalent stress near the bottom of the mesial pulp cavity wall were calculated. RESULTS AND CONCLUSION: (1) Equivalent stress concentration areas: The stress of complete short crown molar and restored models mainly concentrated in the mesial root mesial neck and mesial root lingual neck. The stress concentration area was found in the mesial pulp cavity wall corresponding to the bottom layer of restored models, and the stress concentration was obvious in the 4 mm retention depth group. (2) Under the same repair material, the peak value of dentin equivalent stress was the lowest at 3 mm for all models after repair. The average value of equivalent stress near the bottom of the mesial pulp cavity wall was lowest at 3 mm. (3) Under the same retention depth, there was no significant difference between the two materials in the dentin equivalent stress peak and the mean value near the bottom of the mesial pulp cavity. (4) The results showed that under the conditions of this experiment, the endocrown was used to repair the defect of the short crown molar and the retention depth was 3 mm, which was more beneficial to protect the remaining dental tissue. The selection of zirconia or lithium disilicate as the repair material had little effect on the dentin stress. [ABSTRACT FROM AUTHOR]

The operational procedure of the helicopter requires the maintenance of a consistent velocity to ensure that the rotor blade tip remains within the subsonic threshold during forward flight. However, this approach leads to the drawback of heightened energy consumption. This research was designed to confront this challenge head-on, with the aim of augmenting energy efficiency by enhancing the helicopter performance in both hovering and forward flight scenarios. In order to realize this objective, the focus is on optimizing the rotor structure, particularly the rotor blades, with the aim of enabling dynamic adjustments to the rotor diameter. In order to validate the feasibility of this variable diameter adjustment mechanism, the study begins with a theoretical approach. Subsequently, simulations were conducted employing numerical mechanical analysis. The ultimate goal of these approaches is to compare the equivalent stress experienced by the tool material with its elastic limit. The outcomes stemming from both the theoretical and simulationbased methodologies have culminated in a comparative evaluation of the tool performance. This assessment allowed us to validate successfully the suitability and effectiveness of the chosen approach. [ABSTRACT FROM AUTHOR]

In the process of oil and gas pipeline transportation, elbows are more prone to corrosion compared to straight pipes due to the factors such as load and corrosive media. This article takes pitting defects as the research object. A three-dimensional (3D) nonlinear finite element (FE) model of elbows with pitting defects was established. It further analyzes the influence of factors such as the relative position of defects, the geometric size of defects, and the material properties of elbows. The research results indicate that the ultimate internal pressure of the elbow with pitting defects is influenced by the relative position of the defects. When the defects are located at the inner arch of the elbow, the ultimate internal pressure of the elbow is the smallest. Moreover, the ultimate internal pressure of the elbow with pitting defects is also affected by the size of the defect. The ultimate internal pressure decreases with increase of the depth of the pitting defects and the radius of the pitting defects. Sensitive factors such as pipeline size, pipeline bending radius, and material properties can also have an impact on the ultimate internal pressure of pipelines. Therefore, the conclusions obtained have certain reference value for the safety assessment of elbows with pitting defects. [ABSTRACT FROM AUTHOR]

A pantograph is a key component on the tops of trains that allows them to efficiently tap electricity from power lines and propel them. This study investigates the possibility of using metal matrix composites (MMCs), specifically aluminum MMCs, as a material for making pantograph parts regarding the dynamics of the train's movement and external meteorological conditions. In this study, a computer-aided design (CAD) model is created using PTC Creo design software and moves to detailed finite element analysis (FEA) simulations executed by the ANSYS software suite. These simulations are important in examining how the dynamic performance of pantographs can vary. The incorporation of Al MMC materials into the structure of the pantograph resulted in significant improvements in structural robustness, with equal stress reduced by up to 0.18%. Similarly, aluminum MMC materials reduced the strain energy by 0.063 millijoules. The outcomes not only give a new perspective to the implementation of modern materials but also provide a breakthrough concept to improve efficiency and increase the service life of pantographs. This study marks a significant milestone in the theoretical development of essential train systems, furnishing eminent perspectives toward the tactical development of transportation infrastructure by suggesting new avenues for the smooth incorporation of smart materials in railway transportation, which would contribute to a more sustainable and reliable future. [ABSTRACT FROM AUTHOR]

The principal stress of an arch dam after the equivalent treatment is an important control index of arch dam stress. To explore whether the principal stress calculated by the common finite element equivalent stress method is consistent with the principal stress obtained from direct equivalent treatment of the output principal tensile stress and principal compressive stress calculated by the large finite element software, this paper carried out the stress and deformation calculations of a high-arched dam under the basic combination of conditions through the actual project and then explore the convertibility between the two steps. The results show that the stresses in the heel and toe of the dam are dependent on the mesh size, and the stress concentration can be better reduced after the equivalent treatment; the principal stress calculated by the traditional equivalence step of the finite element equivalent stress method is closer to the principal stress obtained from direct equivalent treatment of the principal stress output by the large finite element software, and the error is basically within 5%. Two equivalence steps are convertible.

This study explores a super-fast magnetic abrasive finishing (MAF) process for polishing the surface of an Inconel 625 bar workpiece for a hydrogen solenoid valve stem. The Inconel 625 bar was chosen to replace the existing STS 316 bar material, previously used for a hydrogen solenoid valve stem. The cylindrical surface of Inconel 625 bars was polished by a super-fast MAF process with high rotational speeds of 1000, 5000, 15,000, and 25,000 RPM and a super-strong magnetic field of 550 mT. The polishing characteristics of this process were evaluated according to the type of abrasives, rotational speeds of the workpiece and processing time. As a result, a super-smooth Inconel 625 bar was successfully achieved, with a surface roughness (Ra) reduced from 0.31 μm to 0.02 μm under the optimal conditions (15,000 RPM, CNT particles (0.04 μm), PCD diamond abrasive (1 μm), Fe (#200), 0.5 g of light oil, and 16 min of processing time). Also, the Ansys analysis results showed suitable strain, equivalent stress, and safety factor of the Inconel 625 bar. This confirmed that, after a super-fast MAF process, an Inconel 625 bar is feasible for application in Hydrogen (H2) tanks instead of a conventional STS 316 bar. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fourteen-gauge solar PV mounting structure installations represent 60% of total solar PV installations in Pakistan. At least 34 (1.72%) structures were damaged on 13 June 2021 with an average 56 km/h wind speed on that day. Therefore, a need arose for a thorough analysis of the 14-gauge solar PV mounting structure. Computational analysis was carried out for 14-gauge solar PV mounting structures. The equivalent stress and total deformation in the structure were calculated computationally. Using computational analysis, it was found that 14-gauge solar PV mounting structures deformed at an 80 km/h wind velocity and broke at a 110 km/h wind velocity. Hence, 14-gauge solar PV mounting structures do not fulfil the building code of Pakistan. [ABSTRACT FROM AUTHOR]

Poor-quality sheet sections and excessive burrs may be resolved by incorporating ultrasonic vibration into the shearing process of hard-to-deform magnesium alloy sheets. It is challenging to simulate the complicated mechanical process of ultrasonic shearing process because it involves material deterioration and fracture, elastic–plastic deformation of the material, and the impacts of ultrasonic indirect sexual contact. Relying on ABAQUS/Explicit finite element simulation software, this paper for the first time proposes a boundary constraint method of constructing a converter to connect displacement reference points and vibration reference points in order to perform numerical simulation of the ultrasonic shearing process of AZ31B magnesium alloy. The team's ultrasonic vibration system serves as the basis for the simulation's shearing model. This model utilizes three variables, namely sheet temperature, shear edge clearance, and ultrasonic amplitude, to analyze the weight coefficients and the influence law on the equivalent stress using the orthogonal test in order to further characterize the processing characteristics of ultrasonic shearing. This research demonstrates that numerical simulation is an effective method for examining the influence of process parameters on stress distribution. The results showed that in the ultrasonic shearing of AZ31B magnesium alloy sheet, the process parameter with the greatest influence on the weight coefficient was the sheet temperature, which was 49.8667, followed by the shear edge clearance, which was 31.2667, and the ultrasonic amplitude, which was 17.5333. When the sheet temperature is 150 ℃, the optimization effect is maximal, and the equivalent stress is reduced by 63.9 MPa. Under identical conditions, ultrasonic shearing substantially reduces the equivalent stress on the sheet compared to conventional shearing. During the ultrasonic shearing procedure, the equivalent stress of the sheet appears to be stress superposition and stress fluctuation, resulting in a significant improvement in sheet section quality. As a result, the paper can serve as a quantitative guide for predicting the ultrasonic shearing quality of the AZ31B magnesium alloy sheet. [ABSTRACT FROM AUTHOR]

BACKGROUND: Intrusion of overerupted posterior teeth with clear aligner for adult patients with different bone densities, orthodontists mostly choose the diaphragm thickness by subjective experience, and finite element analysis is expected to provide a theoretical basis for choosing the appropriate thickness of diaphragms for patients with different bone densities. OBJECTIVE: To analyze the effects of diaphragm thickness and bone density on the intrusion of overerupted maxillary first molar in adult patients using clear aligners using finite element analysis. METHODS: Four groups of finite element models were created based on four bone densities (cancellous bone types I, II, III, and IV) and assembled with three clear aligner models with diaphragm thicknesses of 0.5, 0.75, and 1 mm, respectively. Finite element analysis was then performed using Ansys 2021 software. Clear aligners applied a 0.2 mm intrusion displacement to the maxillary first molar was simulated in each group. The von Mises stress and tooth displacement trends of root, periodontal ligament, alveolar bone of first molar and its adjacent teeth were compared between groups. RESULTS AND CONCLUSION: (1) The von Mises stress distribution of the first molar was the same in all groups, mainly at the root furcation; the second premolar was distributed in the proximal mid-cervical 1/3; the second molar was distributed at the buccal root furcation. (2) The displacement of the first molar and adjacent teeth was close to mesial displacement; the first molar displayed a buccal displacement trend, whereas adjacent teeth displayed a palatal displacement trend. At class II density of alveolar bone, the first molar X- and Y-axis displacement was the smallest, and the Z-axis displacement was the greatest; displacement of adjacent teeth increased with decreasing bone density. In the Z-axis direction, the displacement of the first molar and adjacent teeth was proportional to the thickness of the diaphragm. The smallest displacement was observed in the second premolar 1 mm and second molar 0.5 mm groups in the X- and Y-axis directions. (3) These results concluded that the use of clear aligners to lower the overerupted molars is less likely to cause pericemental fibrosis and root resorption. Decreased bone density does not increase the risk of root resorption. Class II bone density is optimal for molar intrusion. The maximum equivalent stress of the periodontal ligament and alveolar bone is proportional to the thickness of the diaphragm. [ABSTRACT FROM AUTHOR]

The mechanical behavior and constitutive equations of isotropic non-dense metals, such as metal foams, porous metals, and lattice metals, have been extensively studied, but the subsequent yield surfaces depicted by different theoretical models are somewhat controversial and have not been fully validated in the whole permissible loading space. Based on two accepted assumptions for isotropic non-dense metals, we proposed a new plastic flow theoretical model. In order to verify its rationality, we established two mesoscopic models with different initial relative densities and different meso-structures. Then, the large amount of numerical simulation experimental data was established, which covers enough multiaxial loadings in the permissible principle-strain space. Our model solves some of the controversies in current models and adapts the equivalent stress, equivalent strain, and constitutive equations seamlessly to deformation from non-dense to dense state. Numerical results from two mesoscopic models show the relations between equivalent stress and plastic strain in our theoretical model have better consistency under all multiaxial loadings than those in some known models. We checked the topology of subsequent yield surfaces in the plastic principle-strain space and the results turn out the subsequent yield surfaces are not self-similar. The large amount of numerical test data not only well validates our theoretical model but also will be beneficial to the mechanical study of non-dense metals under multiaxial loadings. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Scientific Bulletin of National Mining University is the property of National Mining University, State Higher Educational Institution and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work attempted to investigate the creep behavior of a 7075 aluminum alloy in spray formed and extruded (SFEed) and peak aged (PAed) states by equivalent stress. Arrhenius model and Mukherjee-Bird-Dorn (MBD) model were used to calculate creep parameters. The effects of applied stress or equivalent stress on the creep deformation of SFEed and PAed alloys were discussed and compared. The results showed that the equivalent stress could reasonably evaluate the creep resistance of 7075 Al alloys from the aspects of the steady-state creep rate, creep mechanism and dominate deformation texture, except creep rupture life. Under close equivalent stress, the PAed alloys exhibited superior steady-state creep rates and inferior creep rupture life to the SFEed alloys. The Arrhenius model and MBD model had appropriate ranges of temperature and applied stress to estimate and predict steady-state creep rates, and the accuracy of the MBD model was significantly superior. The stress exponents are computed as 7.03–7.24 for SFEed alloy and 8.11–8.62 for PAed alloy, and the tensile creep mechanism of SFEed and PAed alloys was both dislocation creep. The creep plastic deformation at 0.45–0.65Tm is processed along Cu texture orientation by dislocation climbing rather than S texture. The higher temperature and equivalent stress promote the Cu texture intensity. The applied stress or equivalent stress initiates the slipping and climbing of dislocations, and facilitates the transformation of dominant deformation texture. The main factor that affects grain boundary migration on creep deformation is grain boundary energy rather than stress or equivalent stress.

Fused Deposition Modeling（FDM） has the advantages of fast forming speed and simple operation. Printing speed, printing layer thickness and printing temperature affect the equivalent stress of the workpieces, and then affect its mechanical properties. It is different from direct setting printing temperature as the initial temperature in the birth and death unit simulation. Through experiment and fluid simulation, the temperature of the single fuse when it contacts the plate is got, as the initial temperature of the multilayer superposition simulation. We calculate and fit out the function of heat transfer coefficient, considering printing parameters. With the FDM Multi Layer Stacking simulation, the stress of the workpieces under different parameters is got. Then correlated and compared with the tensile strength obtained by the tensile test under the same parameters. From the point of the stress, we analyzed the influence of the printing parameters on the tensile strength. The supplementary experiment is designed, and find the tensile strength of ploylactic acid（PLA） workpieces reach the maximum when the printing layer thickness is as far as small, the printing speed and the printing temperature are appropriate.

To obtain qualitative and quantitative indicators of changes in the stress-strain state of the nodes of steel bar structures, we identified four characteristic types of nodes. On the basis of modeling in the "Lira-CAD" software package, we analyzed the stress-strain state of four types of nodes for steel trusses with a symmetric and asymmetric design solution. For the research, a calculation of volumetric models of nodes according to the fourth strength theory was performed. At the current moment, the choice of the required thickness of the truss gusset is performed according to the value of the maximum force in the rods. During the nodes modeling it was found that the safety factors depending on the node type for the symmetrical design solution are more than 40 %. The obtained data allow us to reduce the thickness of the gusset taking into account design constraints. It was found that the safety factors depending on the node type for the asymmetric design solution are 7–90 %. The simulation results substantiated the possibility of reducing the gusset thickness for node type 3, and for node types 1, 2 and 4, they showed the necessity of increasing the thickness taking into account design constraints. We derived the refined dependences between the gusset thickness and the maximum force in the attached rods for each structural type of nodes. Based on results of the analysis, we developed recommendations for calculating the most typical types of nodes and presented them in the form of tables and dependencies. For a constructive solution of fastening of gusset braces at an acute angle, we analyzed the influence of the eccentricity value on the stress in gussets. We determined that the main parameter influencing to the stress-strain state of the gusset is the displacement of attached element relative to the axis of the elements fastening. We derived dependences and made graphs of the displacement influence on stresses for different values of gusset thickness.

This research provides a thorough examination of ball bearings from various brands, with a specific focus on 6207 type bearings, using ANSYS simulation software. The bearings under study are sourced from five different brands: KOYO, NSK, Nachi, NTN, and SKF. The study includes a series of tests, with a primary emphasis on assessing static stress when subjected to a 1000 MPa pressure load. Key parameters evaluated in these tests encompass total deformation, equivalent stress, bearing life, and safety factor. The findings from the analyses reveal significant differences among the tested bearings. Notably, KOYO brand bearings demonstrate superior performance compared to their counterparts, characterized by reduced levels of deformation and stress. However, it's important to acknowledge that each brand of bearings possesses distinctive characteristics, comprising both strengths and weaknesses, contingent upon the specific application context. In conclusion, this study underscores the critical importance of thorough testing and analysis in the process of selecting bearings tailored to precise operational requirements. The research highlights the exceptional performance of KOYO bearings under the examined conditions, while also emphasizing the necessity for a nuanced decision making process that takes into account diverse user preferences and varied application demands. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Manny disc brake are produced at conventional machinery workshop. But, the optimum value of disc brake based on heat dissipation, and the safety is unknown. One of the causes of vehicle accidents is the vehicle factor (brake failure). Prolonged and continuous braking on the disc brake can result in fadding. Continuous stress generation can decrease fatigue life. The required material and the right number of holes are needed to solve this problem. The Purpose of this research is to get the optimum temperature and stress value. In this study, simulations were carried out with CAE software on disc brakes with materials Al 7075- T6, SS 304, gray cast iron and the number of ventilation holes 36, 48, 60. The results show that the disc brake with Al 7075-T6 material and 60 ventilaton holes has the best heat dissipation with 38,005ᴼC temperature value. Material gray cast iron with number of ventilation holes 48 produces the lower equivalent stress with 89,272 Mpa. From the research it can be concluded, disc brake with higher density,has higher temperature too. The greater tensile strength of disc brake material, resulting the lower equivalent stress. The gray cast iron material and the number of ventilation holes 48 is the most optimal in temperature absorption, the longest fatigue life, and the highest fatigue safety factor, with a temperature value of 54.99ᴼC, a fatigue life of 100000000 cycles, and an FOS of 3.34.The more number of ventilation holes, has the lower of temperature result but the higher stress concentration.

Hydropower plant can be expected gradually undertake the task of peak shaving and frequency modulation in the power grid, in order to reduce the impact from the renewable energy, such as the solar, and wind energy. In the switch operating conditions of hydraulic turbines, it is a high demand to fully meet the grid requirements during power generation. Consequently, the turbine can be required to work at the off-design conditions, particularly with the high operation stability. This study aims to explore the flow and structure characteristics of Francis turbine under different conditions (0.35Qr, Qr, and 1.09Qr). The turbulence model of SST k-ω was used to solve the internal fluid, whereas the method of fluid-solid coupling was adopted in the structure field. There was the deviation between the relative velocity direction angle of flow and the inlet angle of blade at the off-design points, where the maximum eddy viscosity at 0.35Qr and 1.09Qr were 3.97 and 2.23 times of Qr, respectively. Some parameters were analyzed quantitatively, including the velocity, pressure, eddy viscosity, equivalent stress, and deformation extent. The results show that both Smax and dmax increased with the increasement of load. The large values of Smax appeared at the outlet edge of blade, which was close to the upper crown, whereas the dmax appeared in the middle region of blade outlet edge, under all three conditions. The axial vortex generated by the impact flow at the runner inlet was the main reason for the increment of eddy viscosity, equivalent stress, and deformation extent under off-design conditions, wherein the Smax at Qr is larger than that of 0.35 Qr and smaller than 1.09 Qr, respectively. Stress concentration occurred at the connection area between the blades and the crown, due to the strong constraint at the connection position, where deformation extent was small. However, the dmax appeared at the center position of blades that caused by the strong constraint of upper crown, In addition, the combination of theoretical analysis and numerical simulation was applied to investigate the runner performance, with the different manufacturing materials. The results illustrated that the frequency of Q345 runner at the wet modal shared the highest decrease rate. Among them, the maximum decreasing ratio was 24.5%, which frequency drop rate is bigger than that of ZG00Cr13Ni5Mo. Thus, the fluid damping effect should be fully considered, when using Q345, but Q345 was lighter form the aspect of weight. The critical speed of each material runner was much higher than the working speed of turbine. There was no resonance during this time. The critical speed of ZG00Cr13Ni5Mo runner was the lowest. The runner presented the strongest ability of deformation resistance, when it was made of Q345 and 1Cr18Ni9Ti materials. Therefore, the Q345 was more suitable for the runner manufacture. Moreover, there were the similar developments of static characteristics on the equivalent stress and deformation extent for runners with different materials. Furthermore, all runners with different materials showed the similar vibration modes. Hence, each material can be extended to the other common materials. This finding can provide some reference and guidance for the design and operation of hydraulic turbine. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study explores a super-fast magnetic abrasive finishing (MAF) process for polishing the surface of an Inconel 625 bar workpiece for a hydrogen solenoid valve stem. The Inconel 625 bar was chosen to replace the existing STS 316 bar material, previously used for a hydrogen solenoid valve stem. The cylindrical surface of Inconel 625 bars was polished by a super-fast MAF process with high rotational speeds of 1000, 5000, 15,000, and 25,000 RPM and a super-strong magnetic field of 550 mT. The polishing characteristics of this process were evaluated according to the type of abrasives, rotational speeds of the workpiece and processing time. As a result, a super-smooth Inconel 625 bar was successfully achieved, with a surface roughness (Ra) reduced from 0.31 μm to 0.02 μm under the optimal conditions (15,000 RPM, CNT particles (0.04 μm), PCD diamond abrasive (1 μm), Fe (#200), 0.5 g of light oil, and 16 min of processing time). Also, the Ansys analysis results showed suitable strain, equivalent stress, and safety factor of the Inconel 625 bar. This confirmed that, after a super-fast MAF process, an Inconel 625 bar is feasible for application in Hydrogen (H2) tanks instead of a conventional STS 316 bar.

The behavior of composite materials under tensile and bending loading differs, and material designs optimized for tensile loading may not be suitable for applications subjected to bending loading. In this study, the bending behavior of two different composite materials, namely glass and carbon fiber-reinforced composites, was analyzed under a three-point bending load. The output from the analysis of these two materials was compared, revealing that, in addition to longitudinal direction strength, transverse and through-thickness directional strength, as well as shear strength in all planes of the composite, are essential to minimize deformations, normal stress, and shear stress. In the study, under the same loading and boundary conditions, the carbon epoxy composite exhibited 84% more deformation than the FR-4 composite at the maximum load considered for the study. Furthermore, the strength of the FR-4 composite in the loading direction was 2.4 times greater than that of the carbon epoxy composite. The present work is used for the effective design of the composite material under bending loading.

Abstract Background The objective is to clarify the effect of alveolar cleft bone graft on maxillofacial biomechanical stabilities, the key areas when bone grafting and in which should be supplemented with bone graft once bone resorption occurred in UCCLP (unilateral complete cleft lip and palate). Methods Maxillofacial CAD (computer aided design) models of non-bone graft and full maxilla cleft, full alveolar cleft bone graft, bone graft in other sites of the alveolar cleft were acquired by processing the UCCLP maxillofacial CT data in three-dimensional modeling software. The maxillofacial bone EQV (equivalent) stresses and bone suture EQV strains under occlusal states were obtained in the finite element analysis software. Results Under corresponding occlusal states, the EQV stresses of maxilla, pterygoid process of sphenoid bone on the corresponding side and anterior alveolar arch on the non-cleft side were higher than other maxillofacial bones, the EQV strains of nasomaxillary, zygomaticomaxillary and pterygomaxillary suture on the corresponding side were higher than other maxillofacial bone sutures. The mean EQV strains of nasal raphe, the maximum EQV stresses of posterior alveolar arch on the non-cleft side, the mean and maximum EQV strains of nasomaxillary suture on the non-cleft side in full alveolar cleft bone graft model were all significantly lower than those in non-bone graft model. The mean EQV stresses of bilateral anterior alveolar arches, the maximum EQV stresses of maxilla and its alveolar arch on the cleft side in the model with bone graft in lower 1/3 of the alveolar cleft were significantly higher than those in full alveolar cleft bone graft model. Conclusions For UCCLP, bilateral maxillae, pterygoid processes of sphenoid bones and bilateral nasomaxillary, zygomaticomaxillary, pterygomaxillary sutures, anterior alveolar arch on the non-cleft side are the main occlusal load-bearing structures before and after alveolar cleft bone graft. Alveolar cleft bone graft mainly affects biomechanical stabilities of nasal raphe and posterior alveolar arch, nasomaxillary suture on the non-cleft side. The areas near nasal floor and in the middle of the alveolar cleft are the key sites when bone grafting, and should be supplemented with bone graft when the bone resorbed in these areas.