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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.)

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.)

In recent years, with the rapid advancement of automotive lightweight technology, the mechanical clinching process between aluminum alloy and ultra-high-strength steel sheets has received extensive attention. However, the low ductility of ultra-high-strength steel sheets often results in conventional mechanical clinching processes producing joints that either fail to establish effective interlocks or cause the steel sheets to fracture. To address this issue, a novel mechanical clinching process is presented, called center-punching mechanical clinching (CPMC). This innovative process employs a method of punching, flanging, and bulging gradation to achieve the mechanical clinching of aluminum alloy and ultra-high-strength steel sheets in a single step. In order to determine the effects of different parameters on the quality and strength of the joint, an experimental study was carried out for various die depths and diameters based on the condition of constant punch size. Based on tensile and shear tests, the static strength and failure modes of CPMC joints were analyzed. The results indicated that the CPMC process significantly enhances the connectivity of joints for AA5052 aluminum alloy and DP980 ultra-high-strength steel. Optimal tensile and shear strengths of 1264 and 2249 N, respectively, were achieved at a die depth of 2.2 mm and a diameter of 10.4 mm. The CPMC process provides new ideas for the mechanical clinching of aluminum alloy and ultra-high-strength steels. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the existing simulation and test methods can’t evaluate the influence of aerodynamic load and temperature load on the structural strength and natural frequency of the probe when the probe is installed, the flow-thermal-solid coupling method was proposed to study the structural strength and modal characteristics of the probe measured in the simulated installation state. Firstly, the CFD (computational fluid dynamics) simulation method was used to obtain the temperature and pressure distribution of the probe surface. The temperature data was imported into the Steady-state Thermal module for steady-state thermal analysis to obtain the probe temperature distribution. The aerodynamic load and temperature load were introduced into the static strength analysis module, and the thermal stress and static stress simulation were carried out, and the maximum deformation of the probe body is calculated to be 0.336 mm and the maximum stress of the probe body is 97.867 MPa. The measured probe modal analysis under pre-stress was carried out, and it is found that the natural frequencies of the first six orders are higher than the calculation results of the traditional method, and the natural frequency of the probe differs from the engine more than 10%, and the designed probe has been installed and used, the reliability of the calculation results is verified. [ABSTRACT FROM AUTHOR]

The use of an integrated approach to determining the static strength of operated main pipelines with surface defects makes it possible to take into account the effect of residual weld stresses in combination with operational loads. In this case, it is important to determine the nature of the welding stress distribution for welded structures made of high-strength steels. Here, there is non-uniformity of stresses concerning magnitude and gradient, which is due to technological methods. A mathematical model of the experimental-calculation method is proposed. Such a model allows describing such stresses. A two-parameter criterion for brittle-tough fracture of a material which takes into account the influence of residual stresses is used. It is shown that the combination of residual stresses and operating loads has a significant effect on the safety factor. At the same time, conditions are possible under which compressive residual stresses have a favourable effect on the static strength of a pipeline with a defect. [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.)

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology 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.)

AbstractThe patch repair is a widely used method for repairing the damaged composite structure, optimizing the repair structure in considering static strength and fatigue life can greatly improve the reliability and safety. However, only static strength and fatigue life are considered during the design or optimization. In this article, the multi-objective optimization of composite laminate repaired by patches in considering static strength and fatigue life was carried out. The models used for predicating static strength and fatigue life were established through finite element method (FEM). Then, the established models were adopted to investigate the effect of repair parameters on static strength and fatigue life, results show that patch radius has the strongest impact on static strength and fatigue life, while the repair thickness and stacking sequence of patch show a greater impact on fatigue life. Based on the above conclusions, Non-dominated Sorting Genetic Algorithm (NSGA-II) was employed to optimize the repair structure. The optimization results show that strength and fatigue life was greatly improved, the repair thickness, and patch volume was greatly reduced, patches that radius is larger than 14 mm can ensure that the repair structure has both higher strength and better fatigue resistance. The proposed optimization method has a good optimization effect for composite laminate repaired by patches. [ABSTRACT FROM AUTHOR]

This research work experimentally investigates the effectiveness of various adhesives in bonding Kevlar fiber-reinforced polymer with aluminum alloy 6061-T6 in a hybrid double-strap joint. Hybrid double-strap joints were developed using thermosetting epoxy Araldite LY5052 with Aradur H5052 and thermoplastic epoxy polyurethane mixed with tetrahydrofuran. These specimens were prepared using a hand layup method. Both adhesives were used to make eighty samples: forty for thermoplastic epoxy polyurethane with tetrahydrofuran and forty for thermosetting epoxy Araldite LY5052 with Aradur H5052. In order to determine the static strength of joints, tensile tests were conducted using a universal testing machine (UTM) where a tension–tension fatigue test was carried out on 50%, 70%, and 80% of the static load at which the joint failed. In the thermosetting double lap strap joint, the findings of both the elongation and fatigue tests showed an increase in strength throughout both the elongation and fatigue cycles. Thermosetting Kevlar hybrid joints have a high static and fatigue strength. Based on the results, thermosetting hybrid joints using Aradur H5052 and epoxy Araldite LY5052 had a static strength of 20.67 KN, whereas a thermoplastic adhesive joint had a static strength of 11.93 KN. Furthermore, the microscopic failure modes revealed that the mode of failure for the joints was cohesive and mixed-mode failure. [ABSTRACT FROM AUTHOR]

Aeronautical electronic equipment, used for data collection during flight, is usually fixed to the nose radome using mounting brackets. The stiffness and first-order frequency performance of the mounting brackets is studied to avoid plastic deformation and resonance during flight, which is of great engineering significance for improving flight stability. The static strength and modal analysis of the mounting bracket under inertial load are conducted, and a sensitivity analysis method is used to determine the design variables of the installation bracket. With the goal of minimizing the total weight of the structure as the optimization objective, the thickness of each component of the bracket is optimized while ensuring the stiffness and first-order modal performance of the installation bracket. The vibration tests are conducted for the optimized installation bracket structure. The results show that the stiffness of the optimized installation bracket structure remains basically unchanged, the first-order frequency is increased by 18.09%, and the weight is reduced by 19.33%. The improved design can meet the equipment installation requirements.

In order to obtain the static strength of small modulus plastic gears, a small modulus plastic gear static strength test bench is developed, which can accurately measure the static strength of plastic gears under different modulus, speeds and materials. The working principle, constitution and the design of tooling parts of the test bed are mainly introduced. The test bench is composed of the mechanical system, the electric control system and the measuring software. The electric control system and the measuring software mainly adopt the horizontal structure, which is of the compact structure, with small space occupation, uses simple fixture design and is easy to measure. The static strength test is carried out, and the static strength using different materials is briefly tested. The experimental equipment can realize the measurement of the static strength of the small module plastic gear, which solves the problems of inaccurate static strength test of the small module gear and the difficulty of test clamping, and provides theoretical value and practical application value for the design of the plastic gear in the future.

In order to comprehensively evaluate the feasibility of the engineering application of titanium alloy, the comparative investigations on mechanical performances including the fatigue performance of both aircraft structural maintenance parts and material were carried out based on the different processing methods in which titanium alloy and typical structural samples were respectively made by the selective laser melting(SLM) and traditional mechanical process. As the results, the tensile, shear, and impact properties of titanium alloy by SLM method were excellent at room temperature, and the relative error of various mechanical properties is less than 10% when compared with titanium alloy plates by mechanical process. The aforementioned typical structural samples manufactured by SLM also have the strongest performance of mechanical processing, the relative error of static strength is less than 5%, and the maximum relative error of fatigue strength is 12.9%, titanium alloy typical structural parts manufactured by SLM also have the same level performance of mechanical processing. The reinforcement effect of titanium alloy aircraft structural maintenance parts manufactured by SLM is equivalent to or even slightly better than that of high strength steel by mechanical process. The research shows that the titanium alloy structure made by SLM also meets the basic installation requirement and use.

The cowcatcher is one of the unique devices at the front end of the train, which can remove obstacles on the track by crashing before the vehicle body to ensure the safety of the train. When a collision accident happens, the cowcatcher serves as the first energy-absorbing structure to dissipate and guide the collision energy. The design of the existing cowcatcher of multiple units generally focuses on the good ability to remove obstacles, while the secondary function, the crashworthiness of orderly deformation under collision, still needs further research. In this study, a finite element model of structural static load and collision analysis was established under standard EN 15227, with the cowcatcher for 160 km/h train as the prototype. Then the solution and simulation process was accomplished under the environment of ANSYS and LS-DYNA. The analysis results showed that the structural static strength of the current cowcatcher met the requirements of the standard EN 15227, and the longitudinal stiffness was evenly distributed. When removing the obstacles with low mass, the impact force was small and the structure would not produce obvious deformation; when removing the obstacles with large mass, the impact force was large and the shear fracture might occur at the connection of the cowcatcher.

In recent years, with the rapid advancement of automotive lightweight technology, the mechanical clinching process between aluminum alloy and ultra-high-strength steel sheets has received extensive attention. However, the low ductility of ultra-high-strength steel sheets often results in conventional mechanical clinching processes producing joints that either fail to establish effective interlocks or cause the steel sheets to fracture. To address this issue, a novel mechanical clinching process is presented, called center-punching mechanical clinching (CPMC). This innovative process employs a method of punching, flanging, and bulging gradation to achieve the mechanical clinching of aluminum alloy and ultra-high-strength steel sheets in a single step. In order to determine the effects of different parameters on the quality and strength of the joint, an experimental study was carried out for various die depths and diameters based on the condition of constant punch size. Based on tensile and shear tests, the static strength and failure modes of CPMC joints were analyzed. The results indicated that the CPMC process significantly enhances the connectivity of joints for AA5052 aluminum alloy and DP980 ultra-high-strength steel. Optimal tensile and shear strengths of 1264 and 2249 N, respectively, were achieved at a die depth of 2.2 mm and a diameter of 10.4 mm. The CPMC process provides new ideas for the mechanical clinching of aluminum alloy and ultra-high-strength steels.

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.)

Using a VZh159 superalloy as an example, we consider the formation of the surfaces of the gage portion and the fillet transitions during the selective laser melting synthesis of profiled monolithic cylindrical and flat specimens for mechanical tests. The main defect in the near-surface layer is found to be scattered gas microporosity. After heat treatment, a fine-grained layer forms at the surface of the profiled specimens. When cylindrical synthesized specimens without additional processing of the gage portion surface are tested, their short-term strength characteristics at temperatures of 20, 800, and 1000°C are found to decrease by no more than 3, 4, and 17%, respectively, compared to polished synthesized specimens. [ABSTRACT FROM AUTHOR]

Copyright of Electric Drive for Locomotives is the property of Electric Drive for Locomotives 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 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.)

Introduction. The authors describe the practice of checking newly built cars to assess their durability, taking into account the ultimate operating loads and their application schemes stipulated in the regulatory documents. Axisymmetric loads are not part of the bogie frame static strength assessment rules. For mechanical safety reasons, the presence of residual frame deformation asymmetry is not permitted. All-welded bogie frames are particularly prone to axisymmetric loads. It confirms the need for refinement of design methods to ensure reliability and safety of cars in service.Materials and methods. Methods of computational analysis and computer modelling were used to determine the loading scheme and the magnitude of the axisymmetric load; experimental work was carried out on a passenger carriage with two-axle bogies and an all-welded frame in which the side beams are rigidly connected by cross beams.Results. An additional type of derailment is justified, which is relevant for the operation of wagons with all-welded bogie frames. The load pattern of the bogie frame and the magnitudes of the load applied to the frame for the mode of operation in which the static strength of the frame is to be assessed are determined.Discussion and conclusions. In the event of a wheel derailment, the all-welded bogie frame is subjected to maximum axisymmetric loads, which could lead to axisymmetric deformation and frame failure. The all-welded bogie frame should be assessed for static strength in derailment mode. The overload coefficients are justified. The reliability of the bogie frame in service and the safety of the traffic could be improved by developing, calculating and evaluating the design with the additional mode mentioned above.

The basic fuselage structure is developed primarily based on static strength and stability considerations. The static strength of the bulkhead plays a dominant role in its crack arrest capability. In this investigation, the strength of the rivets and skin in the presence of a longitudinal crack are studied to check the performance of the stiffened panel in arresting the two-bay crack. A finite element analysis approach was used to carry out the parametric study. A stiffened panel with multiple bays was considered for the analysis. The unstiffened fuselage expands uniformly in the radial and longitudinal directions. The fatigue cracks will initiate normally from the highest tensile stress locations. Also, cracks can get initiated due to discrete sources of damage, like tool marks on the surface or pebbles hitting the fuselage. The stress intensity factor (SIF) at different crack lengths was calculated. The panel was analysed with a central bulkhead in broken condition. [ABSTRACT FROM AUTHOR]

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.)

This study presents a new robust formulation for the topology optimization of compliant mechanisms, addressing the design challenges while considering manufacturability, static strength, and fatigue failure. A three-field density projection is implemented to control the minimum size of both real-phase and null-phase material structures to meet the manufacturing process requirements. The static strength is evaluated via the sum of the amplitude and the mean absolute value of the signed von Mises stress. The fatigue failure is solved via the modified Goodman criterion. The real output displacement is optimized by adding artificial springs to the prescribed value. This approach is implemented based on an improved solid isotropic material with penalization (SIMP) interpolation method to describe and solve the optimization model and derive the shape sensitivity of the optimization problem. Finally, two numerical examples are applied to illustrate the effectiveness of the presented method. [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.)

The load-bearing capacities of (i) self-piercing-riveted, (ii) adhesive-bonded and (iii) hybrid riv-bonded lap joints of commercial 1.5-mm-thick EN AW-6016-T4 sheets were compared under both quasi-static and cyclic shear-tensile loads. The joints were heat-treated to cure the adhesive and to peak-age the aluminum alloy. The joint quality/integrity was assessed based on characteristic cross-sectional features and hardness maps. Riveted joints showed notably lower static strength and fatigue performance than riv-bonded joints. Hence, the adhesive layer provided the main contribution to both the static and the cyclic load-bearing capacities of riv-bonded joints, whereas rivets contributed only little. However, if bonding was insufficient the potential capacity of the joints could not be exploited. Under quasi-static loading fracture occurred at the joint; therefore, joints of high quality/integrity were important. Even under cyclic loading at high load amplitudes fracture occurred at the joint, but at comparatively low load amplitudes fracture rather occurred at the sheets next to the joint. Hence, the joint quality/integrity mainly determines the static fracture and the low-cycle fatigue fracture, whereas the sheet properties mainly determine the high-cycle fatigue fracture. [ABSTRACT FROM AUTHOR]

The choice of the proper restorative material is essential for the long-term success of implant-supported rehabilitations. This study aimed to analyze and compare the mechanical properties of four different types of commercial abutment materials for implant-supported restorations. These materials included: lithium disilicate (A), translucent zirconia (B), fiber-reinforced polymethyl methacrylate (PMMA) (C), and ceramic-reinforced polyether ether ketone (PEEK) (D). Tests were carried out under combined bending–compression conditions, which involved applying a compressive force tilted with respect to the abutment axis. Static and fatigue tests were performed on two different geometries for each material, and the results were analyzed according to ISO standard 14801:2016. Monotonic loads were applied to measure static strength, whereas alternating loads with a frequency of 10 Hz and a runout of 5 × 106 cycles were applied for fatigue life estimation, corresponding to five years of clinical service. Fatigue tests were carried out with a load ratio of 0.1 and at least four load levels for each material, and the peak value of the load levels was reduced accordingly in subsequent levels. The results showed that the static and fatigue strengths of Type A and Type B materials were better than those of Type C and Type D. Moreover, the fiber-reinforced polymer material, Type C, showed marked material–geometry coupling. The study revealed that the final properties of the restoration depended on manufacturing techniques and the operator's experience. The findings of this study can be used to inform clinicians' choice of restorative materials for implant-supported rehabilitation, considering factors such as esthetics, mechanical properties, and cost. [ABSTRACT FROM AUTHOR]

This paper presents a finite element model for predicting the performance and failure behaviour of a hybrid joint assembling fibrous composites to a metal part with reinforcement micro pins for enhancing the damage tolerance performance. A unit-strip model using the cohesive elements at the bond interface is employed to simulate the onset and propagation of debonding cracks. Two different traction–separation laws for the interface cohesive elements are employed, representing the fracture toughness properties of the plain adhesive bond and a pin-reinforced interface, respectively. This approach can account for the large-scale crack-bridging effect of the pins. It avoids using concentrated pin forces in the numerical model, thus removing mesh-size dependency, and permitting more accurate and robust computational analysis. Lap joints reinforced with various pin arrays were tested under quasi-static load. Predicted load versus applied displacement relations are in good agreement with the test results, especially for the debonding onset and early stage of crack propagation. [ABSTRACT FROM AUTHOR]

Auxiliary-sheet reinforcing process, a novel enhancing method, was proposed in this study. Auxiliary sheets of four materials were utilized to investigate their effect on joint strength experimentally. The results showed that the AL1060 auxiliary sheet provides the most significant strength improvement for the conventional joint, in both cross-tension and lap-shear strength. With the AL1060 auxiliary sheet, the cross-tension strength of the conventional joints can be increased from 1296 to 1987 N, and the lap-shear strength of the conventional joints can be improved from 1727 to 3378 N. In conclusion, AL1060 provided the best strengthening effect and is the most suitable material to be added to the clinching process. [ABSTRACT FROM AUTHOR]

Clinching technology has been extensively applied as a green and clean joining method, which has the benefits of less energy consumption, no pollution and no noise. However, a single joint produced by round tools cannot withstand the torsion force. In order to solve this problem, a square clinching technology was proposed and investigated in this paper. The main geometric parameters, failure mode, static strength, and energy absorption of the square clinched joint were studied. The fracture characteristics of square clinched joints under different mechanical experiments were studied by a scanning electron microscope. The strength tests of Al5052 clinched joints under various forming forces were carried out. The results showed that the neck fracture mode was the only failure mode observed during the failure process. The microscopic morphology of the joint fracture shows typical ductile fracture characteristics. It turned out that the square clinching process can effectively join aluminum alloy sheets. [ABSTRACT FROM AUTHOR]

The background of this work is the search for the most effective ways of joining composites, inter alia in aeronautical applications. The purpose of this study was to analyze the impact of mechanical fastener types on the static strength of lap joints of composite elements and the impact of fasteners on the mechanism of failure of such joints under fatigue load. The second objective was to check to what extent the hybridization of such joints, consisting of supplementing them with an adhesive joint, affects their strength and the mechanism of failure of such joints loaded with fatigue. Damage to composite joints was observed using computed tomography technology. The fasteners used in this study (aluminum rivets, Hi-lok and Jo-Bolt) differed not only in terms of the materials they were made of, but also in terms of the pressure forces they exerted on the joined parts. Finally, in order to check how a partially cracked adhesive joint affects the load on the fasteners, numerical calculations were carried out. Analyzing the results of the research, it was found that partial damage to the adhesive joint of the hybrid joint does not increase the load on the rivets and does not impair the fatigue life of the joint. An important advantage of hybrid joint is the two-stage destruction of the connection, which significantly increases the safety of aircraft structures and facilitates the process of supervising their technical condition. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Nanchang University (Engineering & Technology) is the property of Nanchang University 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.)

Fillet welded joints are commonly used in steel structures for various engineering applications such as buildings, bridges, railways, ships, and marine structures. Fillet welded joints are generally subjected to static and fatigue loading, resulting in failures of such welded joints. A number of experimental and numerical investigations on the strength and failure behaviour of fillet welded joints have been published. This paper presents a comprehensive review of research results on the static strength, fatigue life, and thermal performance of fillet welded joints. The review covers the various influential factors, such as loading direction, weld geometry, grades of steel, filler materials, welding process, weld penetration, strength mismatch of weld metal, and post-welded treatment. In total, 100 papers were critically reviewed, which were published from 1970 till date. The key findings and research developments on fillet welded joints are summarised. It was found that the transverse fillet welded joints have a higher static strength than the longitudinal fillet welded joints. Filler materials, post-welded treatment, and penetration of weld metal can offer significant strength enhancements in terms of their static and fatigue strength. Lastly, research gaps have been found in the existing body of knowledge, which will help guide future research. [ABSTRACT FROM AUTHOR]

To improve the productivity of the injection molding, it is essential to manufacture the part in the shortest possible period of time while minimising the waste. Additionally, quality of the manufactured part must be ensured by having lowest dimensional deviation, surface defects, and induced residual stresses. However, it is challenging to get a uniform temperature throughout the thick-walled part or complex parts like gear. Therefore, effective design of the gear cavity is essential to minimise volume and maximise surface area to reduce temperature variations. In the present work, modeling and analysis of cavity modification is carried out on involute spur gear to be manufactured by injection molding. The generation of spur gear was carried out using Solidworks software. The same is validated with the data of the sample manufactured gear and found in close agreement for deflection and weight. Further, modifications in the geometry of the generated gear namely rim shape, hub diameter and rim width were made to improve the fill time, core temperature, weight, and maximum ejection time using gear volume reduction and surface area expansion technique. Modification in the gear geometry would result in gear cavity modification. The Moldflow analysis was performed to investigate the effect of cavity modification. The results show decrease in filling time from 0.2024 to 0.1017 s, core temperature from 200.7 to 164.1 °C, weight from 10.26 to 8.17 g, and ejection time from 143.5 to 49.2 s. However, structural analysis result shows increase in deformation from 0.059 to 0.075 mm and root stress from 18.02 to 21.88 MPa. In addition, Moldflow analysis outcomes confirm decrease in teeth deflection from 0.459 to 0.439 mm and residual stress from 28.84 to 25.88 MPa. [ABSTRACT FROM AUTHOR]

During the design of a turbofan engine measuring rake, it was found that the existing strength analysis method was quite different from the actual engine flow conditions, making it hard to simulate the real load on the rake in the engine runner. To solve the above problems, a unidirectional fluid-structure interaction method was proposed. It is found that the load calculated by the unidirectional fluid-structure interaction method is closer to the real installed load. Compared with the traditional method, static stress obtained by the coupling method is reduced from 248.69 MPa to 51.49 MPa, and deformation is reduced from 0.81 mm to 0.16 mm. The top six modals of the rake have increased by more than 7%, successfully avoiding the engine rotor natural frequency. The coupling design method can provide a reference for improving the existing measuring rake design capability, and it can be used in subsequent design and verification calculation of measuring rake. [ABSTRACT FROM AUTHOR]

The article is about press-bolts which are installed by cold forming in sheet metal constructions. Those fasteners belong to functional elements available in form of press-nuts as well as press-bolts. This paper is focused on press-bolt joints, which are equipped with a metric ISO thread according to DIN 13-1 and available in defined property classes related to DIN EN ISO 898-1. The introduced studies provides the scientific basis for further investigations with local fatigue approaches on cold forming joints with press-bolts. In this paper the static load bearing behaviour is determined by experimental as well as numerical investigations at first. In order to be able to describe the static load bearing behaviour sufficiently accurate, the forming simulation with its history of forming due to the installation sequence must also be considered.

With the development of new energy vehicles, the joining of lightweight alloys has received more attention. Self-piercing riveting experiments of aluminum alloy and high-strength steel sheets were performed to analyze the effects of rivet height and laying order of metal sheets on the joining quality in the work. The forming surface, cross-sectional morphology, static tensile property, fatigue property, failure mode, and mechanism were analyzed. The results show that AA5052 alloy and SPFC440 steel can be joined effectively by self-piercing riveting, and there is good contact between rivet head and sheet surfaces. When the rivet is 2.5–3.5 mm higher than the total thickness of two layers sheets, the rivet leg flares symmetrically without cracks or buckling, and the lower sheet completely encapsulates the joint button. The joints have better static tensile properties when the rivet is about 3 mm higher than the thickness of two sheets. The higher static strength is obtained when the aluminum alloy is placed at the lower position. The rivet legs fall off from the lower sheets for all the samples in the tensile tests, which is independent of the rivet height and laying order of metal sheets. The fatigue strength of the sample with the rivet height of 7 mm is the greatest, and the fatigue cracks always occur on the aluminum sheet under all experimental conditions. The findings in this work can help the practical application of self-piercing riveting for aluminum/steel sheets. [ABSTRACT FROM AUTHOR]

The conventional group test method for obtaining probabilistic S - N curve is a time-consuming and expensive test program. This study aims to present an alternative method for determining the probabilistic S - N curve of material based on its static strength data. Firstly, the probabilistic mapping relationship between the static strength and fatigue life of material is elaborated. Subsequently, the Weibull distribution is utilized to model the static strength and fatigue life data of material, and the correlation between the distribution parameters of them is investigated. Finally, an alternative method for determining the probabilistic S - N curve of material is proposed, and the experimental data of carbon steels and composite laminates are applied to verify its validity. The results show that the proposed method is capable of determining the probabilistic S - N curve of material based on its static strength data, which can significantly save test time and reduce test cost. In engineering applications, when the parameters of static strength distribution and the median S - N curve are known, the probabilistic S - N curve with any given survival probability can be determined through a unified analytical expression. [ABSTRACT FROM AUTHOR]

Composite materials are widely used in the construction of means of transport. Due to their low density and high stiffness, sandwich composites generate significant interest. The authors conducted static and dynamic tests in order to determine the effect of density and core thickness on the mechanical properties of a sandwich composite. Particular attention was paid to the impact properties of such composites. Herex and Airex polymer foams of different densities were used as cores, whereas the faces were made up of two layers of fabrics: glass and carbon. The matrix base of the tested materials was made of epoxy resin cured with a dedicated hardener. As a result of the study, a significant influence of the core on the strength parameters of the tested spacer materials was found. The examined polymer foams were found to have different adhesive properties, which affected their residual strength after an impact and the nature of destruction of the studied composites. It was observed that sandwich composites with a thicker core of higher density have higher impact strength and resistance to puncture. In the sandwich composites, low-energy impact loads result in damage only to the layer to which the load has been applied and has a core, so repairing such an element is much easier than in classic layered composites without a core. What is very important is that, in contrast to classic laminates, the bottom cover of the composite is not destroyed at low-impact energy values. [ABSTRACT FROM AUTHOR]

Randomly oriented short fiber reinforced sheet molding compound composites (SMC‐R) are among the most commonly used composites for automotive and many non‐automotive structural applications. Many studies have reported the static and fatigue properties of SMC‐R composites under uniaxial stress conditions. However, there are many applications in which they may be subjected to biaxial stress conditions and their biaxial properties have not been reported in literature. The current study considers the static and fatigue characteristics of a randomly oriented carbon fiber SMC‐R under both uniaxial and biaxial loading conditions with various combinations of tensile and shear stresses. A butterfly shaped Arcan specimen was used to conduct the biaxial stress tests. Since both static strength and fatigue life data exhibited significant variability, statistical analysis was conducted using Weibull distribution to analyse the variations in these properties of the material. In biaxial conditions in which a shear stress is imposed along with a tensile stress, the tensile strength of the material decreases with increasing shear stress. A failure envelope drawn based on von Mises equation shows reasonable agreement with the experimental results. As a percentage of the static strength, the fatigue strengths at 1 million cycles in tension and combined equal tension and shear are significantly higher than the fatigue strength in pure shear. [ABSTRACT FROM AUTHOR]

To decrease the exterior protrusion height and improve the tensile strength of the clinched joint, a rivet-reinforcing method was implemented on the clinched joint in this study. Solid rivets and tubular rivets with the wall thickness of 1.0 mm, 1.5 mm, and 2.0 mm were employed to conduct the rivet-reinforcing experiments on the clinched joints. Mechanical interlock structure measurements and mechanical properties tests were performed on the above-mentioned reinforced joints. The results show that the rivet-reinforcing technology can significantly increase the tensile strength and improve the mechanical behavior of the clinched joint. Compared with the NRJ joint (the reinforced joint with no rivet), the static tensile strength of TRJ-1.0 (the rivet-reinforced joint with the tubular rivet of 1 mm wall thickness), TRJ-1.5 (the rivet-reinforced joint with the tubular rivet of 1.5 mm wall thickness), TRJ-2.0 (the rivet-reinforced joint with the tubular rivet of 2 mm wall thickness), and SRJ joint (the rivet-reinforced joint with the solid rivet) is separately increased by 30.05%, 24.59%, 16.28%, and 7.19%. The TRJ-1.0 joint has the highest tensile strength (1489.57 N) among the five types of reinforced joints in the cross-lap-tensile test. The energy absorption capacity of the rivet-reinforced joints decreases as the wall thickness of the tubular rivet increases. Therefore, the TRJ-1.0 joint has the highest energy absorption that is 5.890 J, while the energy absorption of the SRJ joint is the lowest, which is 2.868 J. The TRJ-1.0 joint has the most excellent strength performance in the lightweight evaluation, which with a lightweight evaluation value of S 1.0 = 2.326 kN / g. However, the TRJ-1.5 joint has the most outstanding energy absorption performance in the aspect of lightweight evaluation, with a lightweight evaluation value of E 1.5 = 5.231 J / g. The experiment has proven that the clinched joints reinforced with 1 mm wall thickness tubular rivets have the best mechanical properties. [ABSTRACT FROM AUTHOR]

The flap peening method with two different shot peening intensities were used to strength the 7B04-T6 for studying the effect of shot peeing on the stress corrosion cracking resistance and mechanical properties of 7B04-T6. Comparative testing about surface roughness, surface residual stress, surface topography, constant load stress corrosion cracking experiment and static strength tensile experiment were performed, the fracture surfaces were observed with SEM. The results show that, shot peening has imparted a surface residual compressive stress of −350 MPa (0.1-0.2 A intensity) and −275 MPa (0.2-0.3 A intensity). The surface roughness has increased from Ra 0.9 μm to Ra 1.6 μm (0.1-0.2 A intensity) and Ra 1.8 μm (0.2-0.3 A intensity). The duration of stress corrosion cracking has extended with 11.3 times (0.1-0.2 A intensity) and 8.7 times (0.2-0.3 A intensity) in the 3%NaCl + 0.5%H2O2 solution and with an application of 350 MPa load. Shot peening has not influenced the ultimate strength and percentage reduction in area, but slightly decreased the yield strength with a value of 15 MPa.

Background: The aim of this study was to determine hormonal responses to acute and chronic exposure to static and dynamic strength training programs using resistance bands in boxers. Material and methods: 19 male national boxers participated in the study. Boxers were instructed to perform strength exercises with resistance bands for 3 days a week for 8 weeks involving either dynamic (n=10) or static (n=9) resistance exercises. Blood samples were taken before exercise, immediately after the initial exercise session, and 8 weeks later following the last exercise session. Cortisol, growth hormone, adrenocorticotropic hormone adrenaline and noradrenaline levels were measured. Statistical analyses involved non-parametric analysis with an alpha level of .05. Results: Dynamic strength exercises were effective stimuli to growth hormone, adrenaline and noradrenaline, while static strength exercises provoked cortisol, growth hormone, adrenaline and noradrenaline responses both initially after exercise and after 8 weeks of chronic training. Neither dynamic nor static strength exercises were effective in prompting adrenocorticotropic changes after an exercise session or after 8 weeks of training. Conclusions: We showed that dynamic and static strength exercise protocols using resistance bands both could provoke acute and chronic hormonal responses in boxers similar to more traditional modes of such exercise. Abbreviations: ACTH ̶ Adrenocorticotropic Hormone, GH ̶ Growth Hormone, C ̶ Cortisol.