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Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical 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.)

Introduction: The analysis of chemoreflex and baroreflex sensitivity may contribute to optimizing patient care and athletic performance. Breathholding tests, such as the Body Oxygen Level Test (BOLT), have gained popularity as a feasible way to evaluate the reflex control over the cardiorespiratory system. According to its proponents, the BOLT score reflects the body's sensitivity to carbon dioxide and homeostasis disturbances, providing feedback on exercise tolerance. However, it has not yet been scientifically validated or linked with exercise performance in highly-trained individuals. Therefore, we investigated the association of BOLT scores with the results of standard performance tests in elite athletes. Methods: A group of 49 speedskaters performed BOLT, Wingate Anaerobic Test (WAnT), and cardiopulmonary exercise test (CPET) on a cycle ergometer. Peak power, total work, and power drop were measured during WAnT. Time to exhaustion and maximum oxygen uptake were measured during CPET. Spearman's rank correlation and multiple linear regression were performed to analyze the association of BOLT scores with parameters obtained during the tests, age, somatic indices, and training experience. Results: No significant correlations between BOLT scores and parameters obtained during WAnT and CPET were found, r(47) = -0.172-0.013, p = 0.248-0.984. The parameters obtained during the tests, age, somatic indices, and training experience were not significant in multiple linear regression (p = 0.38-0.85). The preliminary regression model showed an R2 of 0.08 and RMSE of 9.78 sec. Conclusions: Our findings did not demonstrate a significant relationship between BOLT scores and exercise performance. Age, somatic indices, and training experience were not significant in our analysis. It is recommended to interpret BOLT concerning exercise performance in highly-trained populations with a great degree of caution. [ABSTRACT FROM AUTHOR]

From the recent awareness of the booming number of space debris and their derived worldwide re-entry event threat originating from the use of high survivability components, complementary mitigation measures must be taken for future orbital elements. In this direction, the implementation of a design for demise at an early stage of spacecraft conception allows a progressive and effective solution. As part of a collaborative effort launched by École Polytechnique Fédérale de Lausanne and the European Space Agency, we focus on the evaluation of polymer composite bolts as the main structural satellite panel fastening systems to improve the overall spacecraft demisability during its destructive re-entry into the atmosphere as compared to baseline critical systems, while maintaining equivalent mission-relevant properties. Two carbon fiber-reinforced polyetheretherketone (PEEK) designs were compared to a stainless steel baseline in terms of static properties at room temperature, dynamic properties over a temperature range, as well as demise capability by static re-entry simulation testing. The results led us to identify a promising short CF/PEEK composite bolt design. [ABSTRACT FROM AUTHOR]

To address the inadequacy of research on the bearing behavior of bolted and grouted shallow broken surrounding rock in deep roadways. Broken coal samples with four particle size (PS) were collected, various bolted and grouted broken surrounding rock specimens were subsequently prepared with the collected coal samples by varying the water–cement ratio (WCR) and the number of bolts. The specimens were comparatively analyzed to determine their stress, strain, and crack propagation variation patterns under various parameters. The results showed the following: 1) The bearing capacity of the specimens first increased and then decreased as the PS increased. Under the same conditions, compared to the unbolted specimens, the average peak stress of the bolted specimens was 53.38% higher, whereas their average peak strain was 46.43% smaller. 2) The unbolted specimens primarily underwent tensile failure. The bolted specimens primarily underwent tensile failure, which gradually transitioned to tensile/shear-mixed failure. 3) The bearing capacity of the specimens gradually increased as j increased. However, there were inflection points for the changes in the peak stress and strain. 4) The bearing capacity of the specimens decreased as the WCR increased. However, there was no definite pattern in the morphologies of the specimens at failure. [ABSTRACT FROM AUTHOR]

After analyzing the stress characteristics of the bolt, we determined that it can be regarded as experiencing a planar stress state due to the absence of circumferential stress. Consequently, a photoelastic bolt specimen was fabricated by taking a slice across its diameter. Using a photoelastic bench, we collected interference fringe images of the photoelastic specimen under different loads. This method enabled us to visually and continuously measure the stress distributions within the specimen in real-time. Additionally, the load distribution ratio of each tooth was derived. By comparing these results with those obtained through numerical simulation, we were able to validate the reasonability of the theoretical assumption regarding the load distribution of each tooth in the bolt. Our method establishes a solid foundation and can be effectively utilized for precise thread connection design. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working 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.)

Integrated manufacturing techniques have been extensively utilized to assemble thermal structural components made of continuous fiber reinforced silicon carbide composites (C/SiC) to fabricate large and complex components. The mechanical joint, always in terms of C/SiC bolts, become the weakest link in the components. Laminated C/SiC bolts have been invented to meet the requirements of the high temperature applications. Due to the low shear strengths of C/SiC, the threads are prone to be damaged. In order to fully employ the high tensile strength of carbon fibers, core-shell C/SiC bolt is proposed with the shell prepared by woven fiber architecture. Uniform circumferential microstructure of the threaded teeth has been obtained and the corresponding strength has been improved through fiber bridging mechanism. The results shows that the thread pull-off strength is 17.96% greater than that of the laminated thread tooth, and the stud tensile strength is slightly improved up to 2.96%. The stud shear strength is enhanced by 45.29% and 46.88% with unidirectional C/SiC rod and ZrO 2 ceramic rod, respectively. The improvements are mainly caused by the fiber tension-shear coupling effects. Especially the introduction of unidirectional C/SiC rod improves the shear strength of the bolts by fully utilizing the fiber strengthening mechanisms under in-plane shear loading. [ABSTRACT FROM AUTHOR]

Study on the detection of surface corrosion on bolts using piezoelectric transducers The study investigates the applicability of piezoelectric transducers for the non‐destructive detection of surface corrosion on bolts. The method is based on the measurement of electromechanical impedance spectra, which change in response to varying structural conditions and in principle enable an assessment of the structural condition. As part of the study, experimental and numerical investigations were carried out on four HV bolt sizes in accordance with DIN EN 14399‐4 to test the feasibility of the method. It was possible to demonstrate a correlation between the shift in the resonance amplitude of the bolts and the degree of corrosion. Furthermore, an almost linear trend was observed between the change in shaft cross‐section and the shift in resonance amplitude. In addition, the evolution of the impedance spectra was successfully reproduced by numerical simulation. The results of the study show a promising approach for automated and cost‐effective monitoring of bolt surface corrosion. The application of this technology could lead to significant cost savings and increased safety in various areas of application, especially in the monitoring of areas that are difficult to access and at risk of corrosion. [ABSTRACT FROM AUTHOR]

Background: Some research suggests that physicians who are not neurosurgeons can safely place intracranial pressure (ICP) monitors. The purpose of this study was to compare intracranial pressure monitor placement complications between neurosurgeons, trauma physicians, and general surgery residents. We hypothesized that with appropriate training, general residents can safely place ICP monitors. Methods: A 10-year retrospective chart review of all trauma patients that required ICP monitor placement between January 1, 2012, and December 31, 2021, was conducted. Comparisons were made between treatment groups. Results: During the study period, 194 patients required ICP monitor placement. General surgery residents placed 94.3% of ICP monitors, 3.6% were placed by attending trauma physicians, and 2.1% by neurosurgeons. No ICP monitors were placed by attending trauma physicians or neurosurgeons between 2015 and 2018. Overall, minor complications during ICP monitor placement included device malfunction (2.7%) and inaccurate readings (.5%). There were no major complications during ICP monitor placement. Post-ICP monitor placement complications included one patient who experienced a central nervous system infection (.5%) and three patients who had mechanical problems (1.5%). No complications occurred among the neurosurgeon or attending trauma physician treatment groups. Conclusion: Most intracranial pressure monitors in our study sample were safely placed by surgical residents. Based on our study findings and considering the shortage and downtrend of neurosurgery specialists, ICP bolt placement needs to become a core clinical skill in surgical resident programs across the United States. [ABSTRACT FROM AUTHOR]

To address the frequent occurrence of roof caving, severe over-excavation, and significant ore loss in a mine stope, combined with the limited operating space due to extremely thin ore veins, a bolt + double reinforcing bar support technology is proposed. The essence lies in the timeliness and flexibility of double reinforcing bar support, which allows the entire row of bolt groups to act collectively under the action of the support board during the support process, thereby stabilizing critical rock blocks that may cave in. This support scheme effectively solves the problem of supporting extremely thin ore veins, improves stope safety, and reduces ore dilution, thus enhancing the economic benefits of the mine. [ABSTRACT FROM AUTHOR]

Upon careful examination, numerous wind turbine collapses can be attributed to the failure of the tower bolts. Nowadays, the Schmidt–Neuper algorithm is extensively accepted in wind turbine tower bolt design. It is not advisable to utilize the finite-element method, notwithstanding the effect of the flange gap. To quantitatively investigate the influence of flange gaps on bolt fatigue, a nonlinear finite-element model of a flange segment incorporating bolt pretension and contact elements is herein proposed. Three distinct types of flange gaps are defined intentionally. It is possible to determine the nonlinear relationship between the wall load and bolt internal force. The fatigue damage of bolts was thus computed using the obtained nonlinear curve. Comparing with the results with those of Schmidt–Neuper method revealed the bolt fatigue damage is susceptible to a specified flange gap. [ABSTRACT FROM AUTHOR]

IntroductionThe analysis of chemoreflex and baroreflex sensitivity may contribute to optimizing patient care and athletic performance. Breath-holding tests, such as the Body Oxygen Level Test (BOLT), have gained popularity as a feasible way to evaluate the reflex control over the cardiorespiratory system. According to its proponents, the BOLT score reflects the body’s sensitivity to carbon dioxide and homeostasis disturbances, providing feedback on exercise tolerance. However, it has not yet been scientifically validated or linked with exercise performance in highly-trained individuals. Therefore, we investigated the association of BOLT scores with the results of standard performance tests in elite athletes.MethodsA group of 49 speedskaters performed BOLT, Wingate Anaerobic Test (WAnT), and cardiopulmonary exercise test (CPET) on a cycle ergometer. Peak power, total work, and power drop were measured during WAnT. Time to exhaustion and maximum oxygen uptake were measured during CPET. Spearman’s rank correlation and multiple linear regression were performed to analyze the association of BOLT scores with parameters obtained during the tests, age, somatic indices, and training experience.ResultsNo significant correlations between BOLT scores and parameters obtained during WAnT and CPET were found, r(47) = −0.172–0.013, p = 0.248–0.984. The parameters obtained during the tests, age, somatic indices, and training experience were not significant in multiple linear regression (p = 0.38–0.85). The preliminary regression model showed an R2 of 0.08 and RMSE of 9.78 sec.ConclusionsOur findings did not demonstrate a significant relationship between BOLT scores and exercise performance. Age, somatic indices, and training experience were not significant in our analysis. It is recommended to interpret BOLT concerning exercise performance in highly-trained populations with a great degree of caution.

Since many bolted connections are used in rolling stock, it is necessary to improve the prediction accuracy of stress distribution of the connections in order to reduce the weight and improve the reliability of the structure. In addition, it is important to balance accuracy and reduction computation time by using low-dimensional elements such as shell and beam in the analysis of large structures such as rolling stock. The purpose of this study is to verify the practicality of the simplified finite element modeling method for bolted joints of attachment rails in rolling stock composed of aluminium alloy hollow extrusions, which was proposed in the previous study. In order to understand the behavior of the joints, static load tests were conducted on a full-scale specimen with four attachment rail bolt joints, in which combined tensile, shear, and bending loads were applied, and the strains in the vicinity of the joints were obtained. Simplified modeling using shells, beams, and RBE3 elements was also performed on the specimen. The results showed that the deformation mode of the attachment rail could be reproduced by the simplified model. In addition, the results of the simplified model agreed with the test results in terms of the strain distribution at the nominal section of surface plate and the observed maximum error was 5.0%. It was also confirmed that the simplified model could reproduce the local strain distribution in the extrusion direction and the transverse direction of the extrusion of the attachment rail near the bolted joint. Therefore, we concluded that this simplified modeling method could be practically applied to modeling of bolted joints of attachment rails in actual underfloor equipment of vehicles.

The present work investigates the failure of a bearing cap bolt of a commercial vehicle that suffered a premature failure after running for 1810 kms. Detailed failure analysis has been carried out involving visual inspection, magnetic particle inspection, fractography, microstructural analysis and hardness test. The investigation concludes that the bolt fractured in the shank region due to the presence of seam defect. The crack originated from the seam defect leading to failure of the bolt. It is recommended to emphasize upon adopting best rolling practices pertaining to scale formation and drawing controls for minimization of such defects. [ABSTRACT FROM AUTHOR]

Featured Application: This work will help in the development of new methods for fixing test specimens to the exciters aimed at increasing the safety of vibration testing and the time efficiency of test preparation. The use of electric drives and energy storage devices in vehicles presents fresh challenges for system designers. Among these is addressing the susceptibility of battery packs to mechanical vibrations, necessitating vibration testing. In failure scenarios, like a battery fire, swiftly detaching the battery pack from the vibration platform is vital. It is also essential to ensure that the mounting system—fixture and fastener—effectively transfers vibration between the exciter and the battery pack. The article discusses the basic requirements for the fixture of specimens subjected to vibration testing and fastening it to a slip table of head expander, giving a better understanding of its role. It then presents the results of a theoretical analysis of the fixing forces and their laboratory testing using prototype customized fastening solutions with potential for use in vibration testing. The results of the conducted research and analyses demonstrate that non-standard mounting techniques have limited potential to replace screw mountings in vibration testing, particularly as fully universal techniques. However, the generated mounting forces, with potential resulting from the possibility of tailored implementation of the tested mounting techniques in the design of tables or head expanders, appropriately designed, justify further research work in this area. [ABSTRACT FROM AUTHOR]

When developing the tightening process for composite bolts, ensuring that the target preload(F) required by design is achieved is a key scientific issue in meeting the mechanical properties of the connected structure. Variations in complex process factors during tightening have a large effect on the tightening torque(T)-preload curve(F), and the mechanism by which the tightening process factor affects the target preload must be considered. Using experimental means, the significance and coupling effects of tightening speed, lubrication conditions, tightening areas, joint sealants and washers have been systematically investigated. The tightening torque(T), torque coefficient(K), preload(F) and the peak stress coefficients X (σ) and interlaminar stress coefficients Y (σ) within the composite laminate are used as the main response variables, and a mathematical model between each response variable and the process factor is established to analyse the effect of significant factors on the response variables from a quantitative perspective. Finally, with a certain size of preload(F) as the optimisation target, the optimisation analysis of the tightening speed is carried out for four working conditions with different sealing conditions and different tightening area, and the optimum tightening speed for each working condition is determined. Based on the above study, an analytical method was proposed to determine the reasonable interval of tightening process parameters in this paper. [ABSTRACT FROM AUTHOR]

This paper focuses on the shear behavior of reinforced concrete (RC) beams strengthened with carbon–glass-fiber-reinforced polymer (C-GFRP) plates under different anchoring schemes. The study consisted of four reinforced specimens: specimen CS-1 with no reinforcement and three groups of reinforced specimens SR-1, SR-2 and SR-3. The studies used a four-point bending test to evaluate the reinforcement effect of mechanically anchoring C-GFRP plates. The results of the analysis of load–deflection, strain and bearing capacity indicated that a better reinforcement effect was observed with fiber-reinforced polymer. The test results suggested that the occurrence time of critical oblique cracks was delayed and the development speed of critical oblique cracks was limited by mechanically anchoring the C-GFRP plates. C-GFRP plates significantly increased the stiffness of the reinforced specimen and reflected the superiority of mechanical anchoring. The ultimate shear capacity of the mechanically anchored C-GFRP plates has been significantly improved. With a reasonable increase in the amount of C-GFRP plate, the shear resistance of the test beam became stronger. Compared with the CS-1 specimen without reinforcement, the yield load values of the reinforced specimens SR-1, SR-2 and SR-3 increased by 5.56%, 18.80% and 26.50%, respectively. The ultimate load of reinforced specimens SR-1, SR- 2 and SR-3 increased by 11.64%, 17.47% and 31.51%, respectively. The researchers deduced their theoretical calculation method from the bearing capacity of RC beams strengthened by anchoring with carbon–glass-fiber-reinforced polymer plates. The test findings were in good accord with the theoretical calculation model of bearing capacity suggested in this research. [ABSTRACT FROM AUTHOR]

The investigation into the impact of dry and wet cycles as well as prolonged immersion on the shear properties of bolted rock joints can facilitate comprehension of the mechanism behind shear damage in anchorage rock slopes located within dam sites, which is crucial for conducting long-term stability analyses of such slopes and ensuring safe operation of hydropower plants. In this study, the sandstone from the Three Gorges reservoir area was collected and utilized to made into bolted rock joint specimens, which underwent 12 cycles of wetting and drying as well as 180 days of immersion before undergoing direct shear tests to investigate the degradation of their mechanical properties. The test results indicate that both treatments for water deterioration can significantly reduce the peak shear strength of bolted sandstone joints. The shear deformation characteristics of bolts also vary with the decrease in rock mass strength. As the number of wet and dry cycles, as well as immersion time, increases, the plastic hinge length of the bolt gradually extends. The surface roughness of the joint has an impact on the fracture mode of the bolt. In a flat joint, the fracture section of the bolt exhibits a certain inclination angle, indicating a damage mode where positive and shear stresses act in concert; whereas in a rough joint, the fracture section of the anchor rod shows almost zero inclination angle and is damaged under positive stress. Finally, an attempt was made to apply the conclusions of this paper to engineering by conducting a time-varying reliability analysis of the generalized anchored slope model. The results obtained have significant guidance for evaluating the long-term stability of anchored slopes in hydropower projects.

Comprehensive data on machines is essential for digitization in the industry. Since standardized machine elements are used in most machines, integrating them with sensors provides the opportunity to acquire data comprehensively from in-situ. The sensor integration must not change the element’s core function and the standardized mechanical interfaces. Hence, sensors must be fully integrated and self-sufficient. Regarding bolts as widely used machine element, a solution that combines all the aforementioned requirements does not yet exist. A main problem in developing sensor-integrating machine elements and especially bolts is to overcome the conflicting objectives in defining design space for mechanical and sensory functions. There is a lack of an approach to model the effects of the design space parameters on the mechanical and sensory functions. This paper proposes an optimization function to aid mechanical and electrical engineers in resolving conflicting objectives by balancing function fulfillment when determining design space parameters. Therefore, the effects of the parameters on the mechanical and sensory functions are modelled using FE-analysis and composing an optimization function with weights. This function provides optimal design space parameters. With respect to mountability boundary conditions the optimum for equal weights is at diameters 13.2mm both, increasing v. Mises stress by 29% and strain at sensor position by 80%. The location of the optimum is very dependent on proper weighting, which resembles a prioritization of the mechanical versus the sensory function fulfillment. This enables engineers to find optimal parameters by balancing the mechanical and the sensory function fulfillment.

Arc discharge caused by short-circuit faults is one of the most serious faults in UHV transformers， with the potential for inducing deformation， rupture， burning， or even explosion of the oil tank. In order to analyze the stress-strain levels induced by arc discharge in transformers， a finite element model for a 1，000 kV single-phase UHV transformer was established. The simulation and analysis focused on the pressure distribution within the oil tank caused by arc discharge at different locations and energy levels. Stress-strain levels in both the oil tank and bolts were calculated， with a comprehensive safety check on their mechanical properties based on material parameters. Additionally， the discharge energy thresholds leading to tank wall rupture or bolt damage were determined. The findings reveal that the maximum stress during arc discharge near the high-voltage winding in the oil tank is located at the corner of the tank wall， and the maximum deformation is observed in the middle of the tank wall along the long axis. Furthermore， the maximum stress during arc discharge inside the lifting seat is concentrated at the support of the elevated seat， with the maximum deformation observed at the turning point of the elevated seat.

Physical experiment is a commonly used research method in the field of modern natural science, but the experimental method in a single study is often limited, which cannot fully reflect the whole picture of the problem to be studied. In order to enrich the methodological content in this field, drawing on the ideas of reductionism and systems science, a combination of purpose sampling and subject snowball sampling was used to obtain the analyzed sample literature, and a comprehensive review of the physical experimental research methods of mine bolt was made. In terms of single components, the experimental methods of bolt body, anchoring agent, pallet and metal mesh were summarized and analyzed. In terms of anchoring system, the tensile, shear and similar simulation experiments were summarized and analyzed, and the problems of similar simulation in terms of similar materials, similar structures, similar unstable non-continuous fields, similar processes, similar boundary conditions and similar systems were pointed out. On-site anchorage system experiments can be divided into detective experiments, monitoring experiments, research experiments and other types. In the current physical experimental research on bolt, the experimental objects include component elements, local anchoring systems, anchoring engineering, etc., almost most of the research topics can be classified as performance research, mechanics, materials science experimental methods are used relatively frequent, force, length, time is the basic unit for experimental evaluation. For future research, the existing research can be further enriched by comprehensively applying multidisciplinary research methods, increasing attention to on-site anchored solids, and drawing on system science concepts.

Continuous fiber reinforced and toughened ceramic matrix composites (CMCs) are key thermal structural materials in aerospace and other fields. Mechanical connectivity, as one of the most reliable connectivity methods, is an essential method to achieve connectivity of large and complex CMCs components. At present, research on CMCs joints is rapidly developing, but there is few comprehensive review literature on CMCs joints. Based on the research work in the field of CMCs joints in recent years, the preparation and mechanical property characterization methods of CMCs fasteners were summarized in this paper, the damage and failure mechanism of CMCs fasteners were systematically stored and discussed, and focusing on the influencing factors and laws of mechanical properties of CMCs fasteners from the perspective of material properties and external environment. The research work on CMCs mechanical joints was presented, and the damage law, failure mechanism, finite element simulation and reliability of CMCs connectors were prospected.

Abstract In this study, the competitive failure mechanism of bolt loosening and fatigue is elucidated via competitive failure tests on bolts under composite excitation. Based on the competitive failure mechanism, the mode prediction model and “load ratio—life prediction curve” (ξ–N curve) of the bolt competitive failure are established. Given the poor correlation of the ξ–N curve, an evaluation model of the bolt competitive failure life is proposed based on Miner’s linear damage accumulation theory. Based on the force analysis of the thread surface and simulation of the bolt connection under composite excitation, a theoretical equation of the bolt competitive failure life is established to validate the model for evaluating the bolt competitive failure life. The results reveal that the proposed model can accurately predict the competitive failure life of bolts under composite excitation, and thereby, it can provide guidance to engineering applications.

Copyright of Zhejiang Electric Power is the property of Zhejiang Electric Power 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.)

Practical construction determination of the screwing depth of screws The following report presents a concept for the practical determination of the screw‐in length of bolts in different material combinations. The calculation of the screw‐in length is based on existing publications and guidelines. Since the previous procedure is very complex, a simplified, practical construction concept is developed and presented. The determination is worked out or presented for the usual material combinations (screw to screw‐in substrate) in the construction industry. [ABSTRACT FROM AUTHOR]

Fasteners are subjected to repetitive and variable loads in the areas where they are used. This situation creates some risks such as loosening or fracture of fasteners, result the failure of the joint. Locking chemicals applied on the bolt to prevent loosening that may occur under assembly conditions are used extensively, especially in the automotive industry. By using locking chemicals selected in accordance with the assembly area and fastener, it is aimed to prevent the loosening of the assembly parts under vibration. There are commercial products that offer different properties that can be used in the mass production of locking chemicals. Within the scope of the study, the performance of three different commercial locking chemicals against loosening was investigated and used standard M8 bolts and nuts. In addition, the M8 DIN 980 lock nut, which is used in joints that are at risk of loosening in vibrating areas, was also added to the studies. Due to the effect of the coefficient of friction on the clamping load, all fasteners were coated with the same coating to ensure equivalence in installation conditions. The vibration performances of the locking chemicals were investigated with the Junker vibration test. The results were analyzed comparatively and the joint condition with the highest vibration resistance was determined. As a result, it was observed that the use of locking chemicals and lock nuts increased the loosening resistance. [ABSTRACT FROM AUTHOR]

Most of the rock mass in nature contains a large number of joints, faults and other defects, which make the rock mass have the characteristics of discontinuity and anisotropy, and easily lead to instability and failure of rock engineering. A great quantity of engineering practices show that the bolt has a significant supporting effect on jointed rock mass. Therefore, it is of great significance to study the deformation and failure characteristics of jointed rock mass and the crack arrest effect of bolt for the safety and stability of engineering. A reasonable numerical model of bolted rock samples with non-persistent joints is established by using a three-dimensional Particle Flow Code (PFC) based on the laboratory rock specimens, and the uniaxial compression numerical test is carried out. The results indicate that (1) the numerical simulation results are in good agreement with the laboratory test results, and the variation trend of strength is basically consistent; (2) the different joint angles and anchorage angles result in variations in the mechanical properties of bolted specimens with non-persistent joints; (3) the joint angle has a significant effect on the failure mode of the specimen; (4) the existence of bolts can effectively limit the initiation and propagation process of micro-cracks, and greatly improve the mechanical properties of the specimen containing non-persistent joints. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material 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.)

Let X be a compact metric space, C (X) be the space of continuous real-valued functions on X and $A_{1},A_{2}$ be two closed subalgebras of C (X) containing constant functions. We consider the problem of approximation of a function $f\in C(X)$ by elements from $A_{1}+A_{2}$. We prove a Chebyshev-type alternation theorem for a function $u_{0} \in A_{1}+A_{2}$ to be a best approximation to f. [ABSTRACT FROM AUTHOR]

During tunnel excavation, the stress of the surrounding rock is redistributed, leading to a local stress concentration around the tunnel. In addition, blasting excavation and other factors lead to a strength reduction of rock mass around the tunnel and eventually form a relaxation fracture zone (loosening zone). If supporting measures are not adopted in time during tunnel excavation, the rock strength in the loosening zone will be further reduced and eventually lead to overall instability and collapse. To simulate the bolt/cable supporting effect on the loosening zone and surrounding intact rock, a block–particle–bar coupling algorithm based on penalty springs is proposed. This coupling algorithm is based on the continuum–discontinuum element method (CDEM). CDEM is a dynamic, explicit solution algorithm based on a generalized Lagrange system. A strict controlling equation is established by the Lagrange energy system, and an explicit iterative solution of the dynamic relaxation method is used to realize a unified description of continuous and discontinuous media. The progressive failure of a solid is analyzed through the fracture of the bond between the blocks or particles. Using CDEM, the entire process of the solid from continuous deformation to fracture and movement can be simulated. In the block–particle–bar coupled algorithm, discrete particle clusters are adopted to represent the broken rock mass inside the loosening zone around the tunnel, block elements are used to represent the intact rock mass outside the loosening region, and bar elements are introduced to describe the supporting structures, such as bolts and cables. A contact coupling mode is adopted between particles and blocks, one normal spring and two tangential springs are constructed, and brittle Mohr–Coulomb fracture constitutive law and tensile fracture constitutive law are introduced to represent contact behavior. To realize the transmission of force and displacement, the interpolation coupling approach is adopted between the elements of bars and the elements of discrete particles or blocks. In this coupling mode, penalty springs Sgn and Sgs along and perpendicular to the axis of the bar, respectively, are established. Sgn and Sgs are mainly used to describe the pulling and pushing effect and the lateral compression effect between the bar and the surrounding rock, respectively. The coupling algorithm described in this paper is adopted to simulate the elastic field of a circular shield tunnel, rectangular tunnel reinforced by prestressed rock bolts, reinforcement of full-anchored rock bolts on surrounding rock, and the tunnel support effect in a jointed rock mass. The results of the four numerical cases show the accuracy and rationality of the coupling algorithm. Using this proposed algorithm, the progressive failure process of rock tunnels under high ground stress and the supporting process by lining and bolt (cable) can be accurately simulated.

Implementation of demountable beams in steel‐concrete composite floors enables structure reuse during several life cycles, consequently leading to savings in material consumption and reduction of emissions, providing overall ecological benefits. The behaviour of the innovative demountable beam with a shear connection consisting of headed studs and bolts is analysed in this paper. The proposed beam is formed of a steel profile and a steel‐concrete composite slab cast in open trough profiled steel sheeting. Headed studs, welded to the additional steel angles, are placed in sheeting ribs, whereas bolts are installed between ribs, connecting the steel angles and profile flange. A numerical FE model of a full‐scale steel‐concrete composite beam has been developed to analyse the beam behaviour under service loads. Experimental results of push‐out tests have been used to describe the load‐slip behaviour of headed studs, whereas bolt response has been simulated according to the experimental investigations of lap joints with preloaded bolts and oversize holes. The parametric study has been conducted by varying the bolt diameter, grade and bolt hole size. The results have validated the applicability of the proposed system, confirming the fulfilment of serviceability limit state requirements. [ABSTRACT FROM AUTHOR]

In this study, the competitive failure mechanism of bolt loosening and fatigue is elucidated via competitive failure tests on bolts under composite excitation. Based on the competitive failure mechanism, the mode prediction model and "load ratio—life prediction curve" (ξ–N curve) of the bolt competitive failure are established. Given the poor correlation of the ξ–N curve, an evaluation model of the bolt competitive failure life is proposed based on Miner's linear damage accumulation theory. Based on the force analysis of the thread surface and simulation of the bolt connection under composite excitation, a theoretical equation of the bolt competitive failure life is established to validate the model for evaluating the bolt competitive failure life. The results reveal that the proposed model can accurately predict the competitive failure life of bolts under composite excitation, and thereby, it can provide guidance to engineering applications. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering 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.)

Bolts cannot be loaded axially according to real field conditions in assembly lines. The main reasons for this are that the loads cannot be applied centred due to the plate thickness and the holes are wider than the bolt. This creates a change in the shear loads on the plate connections due to the moment. Therefore, in this study, a software including additional equations has been developed to reveal the moment formation which the bolts are exposed to. This program, prepared in Matlab software, first determines whether the material properties and thickness of the plate can withstand this tensile force when two bolt-connected plates are subjected to tensile force. If the plate is resistant to these tensile forces, the calculation is continued and the maximum shear stress on the bolts is calculated. For the experimental study, 5 samples with M6 bolt connections were prepared and tensile tests were carried out. The accuracy was measured by comparing the software result with the tensile tests and the finite element analysis results made in the Ansys program. In addition, a method for topology optimization is presented in order to improve the position of the connections on the plate.

Cross-laminated timber (CLT), a wood product with excellent shear resistance, is often used in modern timber constructions. Using the standards ASTM D1761-12 (2020) and NDS-2012 (2012), this study investigated the connection properties of shear bolts and screws in CLT panels. The specimens were made from spruce-pine-fir lumber and installed on a test platform using one high-strength bolt or eight screws, and then an upward load was applied to the top of the specimen. The results showed that the bolt connection provided a higher ultimate bearing capacity and elastic stiffness. The bolt exhibited virtually no deformation, and the CLT panel did not noticeably deteriorate when the connection was damaged. The distance between the bolt hole and the bottom of the CLT specimen and the angle between the outer-layer grain direction of the CLT panel and the load direction were both measured. Changes in the ductility coefficient value had an obvious effect on the connection performance of the shear bolts when the outer-layer grain direction of the CLT panel was consistent with the load direction. Contrastingly, when the outer-layer grain direction of the CLT panel was perpendicular to the load direction, the effect was negligible, and the yield load was nearly unchanged.

Torsional deformation of an elastic half-space containing a vertical cylindrical cavity caused by a rotation of a bonded rigid bolt with a long shank is studied in this article by employing Weber integral transforms and integral equations. In the limiting case of the infinite shank, we suggest two different techniques reducing the problem to the regular integral equations of the second kind, which permit efficient solutions in distinct ranges of geometric parameters and allow us to derive a highly accurate approximate analytic solution of the problem for any values of the parameters. Almost exact approximations are suggested for the stress concentration at the edge of the bolt head. In the case of a bolt with a long finite shank, relationships between the torque and the angle of twist of the bolt are derived by utilizing solutions obtained for the bolt with the infinite shank as asymptotic approximations. The effect of the geometric parameters is investigated providing insight into the behavior of the bolt and contact stress in dependence on the bolt head radius and the length of the shank. [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.)

Improper design or maintenance of threaded fastener bolted joints can lead to safety issues and/or loss of life due to failure of the joint. This paper describes the effect of multiple uses of threaded fasteners on the associated loss of preload. Experimental test data is used to model the behaviour of fastener usage against preload loss; a predictive capability is derived accounting for fastener diameter changes. Assessment of the behaviour identifies that fastener thread pitch is an important contributor to the decay of preload due to reuse. [ABSTRACT FROM AUTHOR]

Upon careful examination, numerous wind turbine collapses can be attributed to the failure of the tower bolts. Nowadays, the Schmidt–Neuper algorithm is extensively accepted in wind turbine tower bolt design. It is not advisable to utilize the finite-element method, notwithstanding the effect of the flange gap. To quantitatively investigate the influence of flange gaps on bolt fatigue, a nonlinear finite-element model of a flange segment incorporating bolt pretension and contact elements is herein proposed. Three distinct types of flange gaps are defined intentionally. It is possible to determine the nonlinear relationship between the wall load and bolt internal force. The fatigue damage of bolts was thus computed using the obtained nonlinear curve. Comparing with the results with those of Schmidt–Neuper method revealed the bolt fatigue damage is susceptible to a specified flange gap.

The use of electric drives and energy storage devices in vehicles presents fresh challenges for system designers. Among these is addressing the susceptibility of battery packs to mechanical vibrations, necessitating vibration testing. In failure scenarios, like a battery fire, swiftly detaching the battery pack from the vibration platform is vital. It is also essential to ensure that the mounting system—fixture and fastener—effectively transfers vibration between the exciter and the battery pack. The article discusses the basic requirements for the fixture of specimens subjected to vibration testing and fastening it to a slip table of head expander, giving a better understanding of its role. It then presents the results of a theoretical analysis of the fixing forces and their laboratory testing using prototype customized fastening solutions with potential for use in vibration testing. The results of the conducted research and analyses demonstrate that non-standard mounting techniques have limited potential to replace screw mountings in vibration testing, particularly as fully universal techniques. However, the generated mounting forces, with potential resulting from the possibility of tailored implementation of the tested mounting techniques in the design of tables or head expanders, appropriately designed, justify further research work in this area.