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We investigate the propagation characteristics of two temporally separated soliton pulses with the same spectra, under the influence of stimulated Raman scattering, within a single-mode optical fiber. This analysis explores the behavior of the interacting solitons while propagating in different chalcogenide materials, exhibiting new features and promising prospects for soliton transmission in optical communication systems. Our study included all the interaction parameters constituting the nonlinear Schrödinger equation (NLSE). We have examined the relationship between the Kerr nonlinearity, interpulse and intrapulse Raman effects, and material-dependent collision length featuring a key aspect in logic design and phase control in mode-locking systems. We have also systematically shown the manifestation of the Raman response function from the Raman gain curve, which our mathematical model (the Lorentzian model) provides, that exhibits a near agreement with experimental data. Our findings reveal significant differences from the typical behavior of two-soliton interaction only due to Kerr nonlinearity. Furthermore, we have investigated the mechanism of the net energy transfer between the interacting solitons as an integral phenomenon involved in multiple soliton propagation. These results provide an insightful understanding of the associated nonlinear effects in high-power soliton transmission systems and are foreseen to possess the potential for designing advanced optical switches and mode-locked lasers. [ABSTRACT FROM AUTHOR]

The behavior and design of duplex stainless steel double-lap shear bolted connections produced by wire arc additive manufacturing (WAAM) are explored in this paper. A thorough experimental study carried out on 45 WAAM duplex stainless steel bolted connections with different bolt hole positions, surface conditions (milled or unmilled), and loading orientations relative to the printing direction is first presented. Details are described of the manufacturing process, which featured ER2209 feedstock wire, specimen geometries, which were determined via three-dimensional (3D) laser scanning, and testing of the bolted connection specimens. The failure modes, load-displacement responses, as well as strengths with and without consideration of the bolt hole deformation, are reported. The bolt hole position, rather than the loading orientation or surface condition, was found to have the strongest influence on the behavior of the tested WAAM duplex stainless steel double shear bolted connections. Given the lack of specific design rules for bolted connections between WAAM sheets, the applicability of existing design methods for conventional steel and stainless steel connections has been assessed. The connection test capacities were compared against the strengths predicted using the design expressions set out in three American specifications—AISC 360-22, AISC 370-21, and ASCE 8-22—and in the literature. It was found that existing design methods were generally able to predict the strengths of WAAM duplex stainless steel double shear bolted connections well, both with and without consideration of bolt hole deformation. [ABSTRACT FROM AUTHOR]

Detecting bolt looseness in flanged pipes at an early stage is critical for ensuring safety in the oil and gas industry. Failure to identify such looseness can lead to severe incidents such as leaks and explosions. One effective indirect method for detecting looseness is through vibration analysis of the structures connected by bolted joints. Changes in vibration parameters can indicate looseness, which affects the bolted joints' structural stiffness. This study presents a novel parametric modeling algorithm for detecting bolt looseness in flanged pipes. Autoregressive (AR) model parameters serve as the feature vector for a Mahalanobis distance–based indicator, facilitating accurate looseness detection. Validation was conducted using AR and time-varying autoregressive (TAR) models adapted to the stationary and nonstationary vibration signals of flanged pipes, respectively. The structure was excited using white noise (stationary state) and a moving mass inside the pipe (nonstationary state) to ensure practical applicability. The results demonstrate the method's effectiveness in detecting flange looseness at early stages using an output-only approach. Practical Applications: The developed vibration-based method for detecting flange bolt looseness offers significant practical applications, especially in pipeline integrity management. A novel application involves using a pipeline inspection gauge (PIG) as a moving mass, leveraging its movement within pipes for dynamic excitation similar to the study's approach. Integrating this method with pigging operations enables real-time monitoring of pipeline health. Vibration responses induced by the PIG were analyzed using TAR models and Mahalanobis distance–based indicators to detect various structural issues such as flange bolt looseness, weld cracks, and erosion- and corrosion-induced material loss. However, further investigation is needed to integrate the hardware (such as accelerometers) with the PIG itself, and this is currently under study. Practically, this approach offers: • Early detection of structural defects: identifies issues like flange bolt looseness early, facilitating timely maintenance to prevent failures. • Continuous monitoring: utilizes existing pigging routines for cost-effective, ongoing structural health monitoring. • Enhanced pipeline safety: early defect detection enhances overall safety and reliability. • Improved maintenance scheduling: early detection allows for better planning, reducing downtime and costs. • Applicability to various pipeline systems: adaptable to different pipelines, enhancing its utility across the industry. In conclusion, integrating this vibration-based method with pigging operations offers an efficient solution for maintaining pipeline integrity. By providing early defect warnings, it significantly boosts safety, reliability, and operational efficiency. [ABSTRACT FROM AUTHOR]

Bolted joints, prevalent in industrial applications for component fastening, are susceptible to self-loosening—a critical issue resulting in a gradual reduction in clamping force. Gaining insight into the underlying mechanisms of self-loosening is crucial. While prior research has largely focused on evaluating component stiffness, limited attention has been given to its impact on the self-loosening behavior of bolted joints under transverse cyclic loading. This study investigates how component stiffness influences self-loosening in bolted joints by varying the material and thickness of clamped members. An experimental setup replicating real-world conditions is devised to simulate loosening caused by cyclic lateral displacement. Tests are conducted using steel and high-density polyethylene (HDPE) clamped members of different grip lengths to explore the relationship between stiffness and self-loosening. Key parameters measured include bolt axial load, transverse force on clamped members, relative displacement, and rotation between the bolt and nut. The findings provide valuable insights into the effects of stiffness across various clamped member materials and grip length combinations, which can enhance the understanding of conditions that promote loosening resistance. Moreover, by highlighting stage-II or rotational loosening, with each test resulting in complete preload loss, the study provides a comparative analysis of the influencing factors. This enables the identification of distinct loosening patterns and supports the development of improved bolted joint designs to reduce loosening. [ABSTRACT FROM AUTHOR]

Highlights Reasonably designed hybrid joints can combine the advantages of both adhesively bonded and bolted joints, and have potential application value in improving the bearing capacity of the joint and ensuring structural safety. However, the failure behavior and damage mechanism of multi‐materials hybrid joints are not fully understood. In this paper, the mechanical performances of bonded, bolted, and hybrid CFRP‐aluminum alloy joints under tensile load were investigated using experiment and simulation methods. Based on the quasi‐static tensile test and fractography analysis, the mechanical behavior and damage mechanism of the three kinds of joints were studied, and the effects of hybrid effects were analyzed. The results demonstrated that there is no obvious co‐bearing effect between the adhesive layer and the bolt within the hybrid joint. Instead, a sequential load transfer behavior was observed. The hybrid joint showed more severe damage compared with the bolt joint, especially the CFRP delamination. Furthermore, a numerical model based on continuous damage mechanics (CDM) was established, the LaRC05 initial failure criterion and linear damage evolution were implemented to predict composite intra‐laminar failure, and the cohesive zone model (CZM) was used to simulate the inter‐laminar delamination and adhesive layer fracture. The model considers in situ effect, shear nonlinearity, and employs the selective parabola algorithm to improve computing efficiency. The comparison between experiment and simulation reveals that the model can accurately predict the mechanical performances of joints and capture the various failure modes. The performances of bonded, bolted, and hybrid CFRP‐aluminum alloy joints. The CDM model of CFRP includes LaRC05 criterion and stiffness degradation. Effect of damage constitutive models on the failure simulation of CFRP. Damage  evolution and failure modes of three types of joints. [ABSTRACT FROM AUTHOR]

This paper proposes a high-strength prestressed bolt that experiences both high strength and high elongation. Its elastic modulus is larger, and spiral ribs appear, which is referred to as the NPR bolt. The influence of different elastic moduli and spiral appearances on the bonding performance of the resin was analyzed. Theoretical analysis and FEM are used to analyze the influence of different elastic moduli on the mechanical distribution of the resin–rock interface. The results of the two methods are consistent. The maximum values of the interface shear stress and the axial force appear at the loading end, the minimum values appear at the end of the bolt, and both decays exponentially. With the increase in the elastic modulus of the bolt, the attenuation rate decreases, and the distribution becomes more uniform. The greater the elastic modulus is, the more positive the bonding performance of the resin–rock interface. The load transfer mechanism of the bolt–resin interface of a spiral rib under axial force was studied. With the same diameter and rib height, the spiral ribs of the NPR bolt can be more fully combined with the bonding agent to bear a greater tension load. Taking the NPR spiral and T-1 bolt used in this paper as examples, the bonding performance of the former is 2.24 times that of the latter. The loads of the spiral bolt and the inclined rib bolt are mainly borne by the ribs, accounting for 98.4% and 96.9%, respectively. The resin bonding performance experiment was carried out on an NPR spiral and commonly used T-1\T-2 resin bolts. From the experimental results, the spiral rib structure of the NPR bolt has excellent bonding performance with the resin, which can fully guarantee the bonding performance between the bolt–resin interface. With a resin anchor length of 600 mm, the average peak axial force of the NPR spiral bolt reaches 207 kN, and those of the T1 and T2 bolts are 163 kN and 139 kN, respectively. The NPR spiral bolts did not fail at the bolt–resin interface. Failure of the 1/4T-1 bolt and 3/4T-2 bolt occurred at the bolt–resin interface. The research results of this paper can provide a reference basis for the anchorage design of similar high-strength bolts with a spiral appearance. Highlights: A new type of prestressed anchor bolt with high strength and high elongation is proposed, which is anchored by resin and mechanical-type anchorage. Its elastic modulus is larger, and its appearance adopts the design of spiral ribs. The influence of the elastic modulus of the bolt on the bonding performance of the resin–rock interface was revealed. Under the same axial load, the larger the elastic modulus of the bolt, the more uniform the interface shear stress distribution. The mechanical transfer model of the spiral rib bolt–resin interface was established and analyzed. In addition, the experiment was carried out. Under the same bolt diameter and rib height, the interaction area between the spiral rib and the resin is larger, which can provide greater load. [ABSTRACT FROM AUTHOR]

The equivalent T-stub method is frequently employed in infrastructure projects, including bridge engineering, to simplify bolted connection analysis. However, steel connections remain inherently complex due to nonlinear behavior, cost considerations, and code compliance, framing the design process as a discrete structural optimization problem. This research addresses these challenges by presenting a comprehensive calculation framework that combines the finite element method (FEM) and genetic algorithm (GA) to accurately evaluate the structural performance of bolted T-stub configurations. The proposed approach accounts for nonlinear behavior, thereby reflecting realistic structural responses. To enhance the simulation efficiency and reduce the computational time without significantly compromising accuracy, the study introduces a simplified modeling methodology. The effectiveness of the approach is demonstrated through the development and experimental validation of a selected T-stub connection. Furthermore, a parameter sensitivity analysis is conducted to showcase the range of possible outcomes, emphasizing the potential for optimization. Finally, the proposed connections were optimized using GA, highlighting the benefits of structural optimization in achieving efficient and precise designs for steel connections. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe 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.)

Bolted joint is widely used in construction, vehicle, aerospace, and other engineering fields. Bolt tension is the most important performance index of bolted joints. The whole life cycle monitoring of bolt tension without contact and damage can be realized by vision-based method. The existing methods indirectly predict the change of bolt tension by calculating the rotary angle of the nut. This kind of method can judge the loosening caused by nut rotation but cannot deal with the non-rotary loosening. At the same time, the relationship between nut rotation angle and loosening must be obtained through calibration experiments. This paper proposes a vision-based method to measure the change of bolt tension considering the non-rotary loosening by detecting the change of bolt elongation. Based on VDI2230 and finite element analysis, a new calculation method of bolt flexibility coefficient is proposed. The experimental results show that this method can measure the change of bolt tension with high precision in the process of tightening and loosening. [ABSTRACT FROM AUTHOR]

This study tested a unique assembly method using single and multi-body sleeves with carbon fiber-reinforced plastic (CFRP) to improve load-carrying capacity in single-lap joints. Advanced techniques were implemented into FE code to simulate progressive material degradation behavior. Ti6-4 bolt, insert, and washers with AISI 304L sleeve joint were conceptually designed to keep bolt and nut together with less relative motion. Failure indices were reduced by 16–54%, damage initiation force was improved by 8–40%, and inter-plate clamp loss was reduced by 18% compared to the sleeveless design. Lateral load-carrying capability of joint and inter-plate clamp load significantly improved. [ABSTRACT FROM AUTHOR]

The impact of rock bolts on the mechanical behavior of nonpersistent joints, including the intricate interactions between the joints, rock bridges, and rock bolts, has received limited investigation despite their effectiveness in reinforcing rock mass discontinuities. In order to tackle this issue, a variety of normal stresses were applied during direct shear tests conducted on artificial rock-like specimens with nonpersistent joints, both bolted and unbolted. Meanwhile, to measure the deformation in the rock bridge and joint plane region, a set of strain gauges were implemented. The findings indicated that the local shear deformation-shear displacement curves, whether with or without rock bolts, can be categorized into five distinct stages. Application of the rock bolts on the nonpersistent joint plane resulted in making the following two important statements: (a) The rock bolts delay the shear stress transmission along the joint plane from the joint parts to the rock bridge area; (b) The rock bolts limit the dilatancy occurring in both the joint parts and at the rock bridge area. Furthermore, the shear displacement of the bolted nonpersistent joint specimen at the peak shear strength was found to be greater than that of the unbolted nonpersistent joint specimen indicating protection of the rock bridge by the rock bolts. Whether bolted or unbolted, the stiffness values seem to be the same for the nonpersistent joint plane for a selected normal stress; this observation is significantly different from that observed for the persistent joint plane. [ABSTRACT FROM AUTHOR]

In this paper, the mechanical properties, damage modes, and bolt load distribution of the bonded‐bolted hybrid three‐bolt joint were investigated by a combination of experiments and numerical simulations. Acoustic emission (AE) was used to monitor the tensile process of the connection in real time, and the K‐means clustering algorithm was used to realize the cluster analysis of the damage modes. A numerical simulation model of the tensile process of the joint was established using ABAQUS simulation software. The progressive damage evolution of composite laminates, and adhesive layer was characterized by using the VUMAT subroutine, the B‐K failure criterion, and cohesive element with zero thickness, respectively. The results show that four main damage modes occur in composite laminates during tension: matrix cracking, delamination, fiber pull‐out, and fiber breakage, with corresponding peak frequency ranges of (0–80 kHz), (80–210 kHz), (210–330 kHz), and (330–375 kHz), respectively. The adhesive layer between the laminates mainly exhibits peeling failure because of the secondary bending effect. In the load‐bearing process, the adhesive layer was loaded first and failed, and the bolt loading was delayed. Meanwhile, the results of bolt load distribution showed that the bolts and the adhesive layer at both ends carried greater loads. Highlights: Damage modes and damage evolution of the bonded‐bolted hybrid joint in tension were analyzed by combining acoustic emission technology and numerical simulation.The simulation of delamination damage in composite laminates was carried out by inserting zero‐thickness cohesive elements into the laminates, and the delamination damage between the carbon fiber layup and the adjacent glass fiber layup was analyzed.The effect of the inclusion of the adhesive layer on the mechanical properties of the joint and the distribution of the bolt load was analyzed. [ABSTRACT FROM AUTHOR]

It is important to study damage evolution as well as failure of carbon fiber reinforced polymer (CFRP) plates bolted joints. Therefore, the quasi‐static tensile test on single‐lap and double‐lap CFRP plates bolted joints was conducted. Meanwhile, the tensile strength prediction model for titanium alloy bolted joint of CFRP plates was established based on the improved 3D Hashin failure criterion, then a theoretical model was proposed to accurately predict the load distributions and tilt angle of bolted joints. Thus, the load–displacement curves were divided into four stages, and load distributions at different stage points as well as the relationship between tilt angle of bolt and load variation were obtained. The damage evolution of single‐lap and double‐lap at different stage points was analyzed respectively, and failure mechanisms were revealed based on load distribution. The results show that the ultimate failure of single‐lap is caused by the intrusion of bolt head into CFRP plates, while double‐lap is caused by the compression deformation of central plate. The numerical simulation works are in high agreement with the experimental results. Highlights: Calculate the load distribution at single‐lap and double‐lap bolted joints.Obtain the relationship between bolts tilt angle and load variation.Analysis of damage evolution in bolt‐hole wall of carbon fiber reinforced polymer (CFRP) plates.Using loads to reveal the failure mechanisms of single‐lap and double‐lap bolted joints of CFRP plates. [ABSTRACT FROM AUTHOR]

Rock masses are formed through long-term, complex geological processes, and the presence of joints significantly reduces their strength and increases their deformation. Rock bolts effectively enhance the strength and stability of rock masses and are extensively utilized for reinforcement. According to field investigations, a significant portion of the damage to bolted rock masses stems from shear deformation at joint surfaces. Moreover, roughness affects friction and surface contact, thus influencing the shear behavior between rock and rock bolts. This study considers two crucial factors affecting the shear characteristics of bolted rock joints: joint surface roughness and normal stress. Using the Particle Flow Code discrete element numerical method, the Barton standard joint profile lines were input to establish numerical models of both unbolted and bolted rock joints for direct shear tests. Results reveal that the peak shear stress and stiffness of both unbolted and bolted rock joints increase with rising normal stress and joint roughness coefficient. The peak shear stress and stiffness of bolted rock joints are notably higher than those of unbolted ones, with a maximum increase of 17.5%. Crack development in bolted rock joints occurs in stages of rapid, slow, and stable development, whereas no distinct slow development stage is observed in unbolted rock joints. Additionally, micro cracks in both unbolted and bolted rock joints are primarily tensile cracks, originating around the joint surface and extending outward with increasing shear displacement. These findings offer valuable insights into the microscopic shear mechanics of bolted rock joints and provide practical references for engineering design and applications in rock reinforcement projects. [ABSTRACT FROM AUTHOR]

AbstractBolted connections are widely used in the assembly of aeroengine casings, and the uniformity of residual pretension of bolts is considered one of the important criteria for evaluating the structural performance of bolted connections. This paper is based on the theory of elastic interaction between bolts, and constructs theoretical models of bolt group pre-tightening force for single bolt and double bolts pre-tightening during the pre-tightening process. This model can obtain the residual preload distribution of each bolt with known initial preload force, and re solve the initial preload force. During the analysis process, the influence of different pre-tightening sequences and pre-tightening steps on residual pre-tightening was analyzed. It was found that using specific pre-tightening sequences and increasing pre-tightening steps can effectively reduce the impact of elastic interaction on residual pre-tightening force of bolt groups. At the same time, the difference correction method is used instead of the reverse solution method to solve the initial pre-tightening force for the double bolts pre-tightening model, making the residual pre-tightening force of the bolt group more evenly distributed. In addition, this paper also conducted single step and multi-step bolt pre-tightening experiments and compared them with the theoretical model, fully proving the correctness of this model. The method of constructing the bolt pre-tightening theoretical model of the bolt group connection system in this paper can be widely applied to other aerospace bolted connection systems, effectively guiding the assembly process design, optimization, and improving the performance of the connection structure of actual aerospace engine casings in engineering. [ABSTRACT FROM AUTHOR]

This paper presents the experimental results of Grade 8.8S high-strength steel coupons tensioned to fracture at room and elevated temperatures, followed by finite element analyses for investigating the ductile fracture behavior. Smooth round bars, notched round bars, flat shear sheets, and flat grooved sheets were tested at room temperature, which covered a wide range of stress states. The relationship between the ductility of the Grade 8.8S high-strength steel and the stress state was discussed. Extra smooth and notched round bars were also redesigned and tested at elevated temperatures. The nonlinear variations of material properties, including elastic modulus, yield strength, and tensile strength, were discussed. Different modeling strategies were used for the room and elevated temperatures. At room temperature, three uncoupled ductile fracture criteria were evaluated regarding their applications in the Grade 8.8S high-strength steel. Besides, in conjunction with a modified Johnson–Cook (JC) hardening model, the JC fracture criterion was improved and characterized by an exponential temperature function, as the original linear temperature function could not accurately describe the relationship between the fracture strain and temperatures. The developed finite element models closely traced most specimens' load-displacement paths at the room and elevated temperatures. [ABSTRACT FROM AUTHOR]

In order to solve the problem of difficult simulation of the bolted joint structure of rotors, this study proposes an improved sub-regional thin-layer element method (ISRTL) and applies it to the equivalent simulation of the joint interface in the presence of bolt deviations. The theory introduces the fractal theory and Hertz contact theory to calculate the thin-layer parameter for the region with weak influence of bolt preload. The trend of dynamic response under different loosening deviation conditions is investigated. The experimental study of bolt deviation under axial tension and transverse vibration was carried out using a drum-disk rotor. The frequency and stiffness with bolt loosening position conform to M-type trend. The error of the eigenfrequencies calculated by the proposed method is within 3 % from the experimental results. The results demonstrate that ISRTL method has high accuracy and efficiency in the simulation study for the assembly deviation of rotor bolt connections. [ABSTRACT FROM AUTHOR]

Bolted connections are a highly efficient joining method, especially for constructions with mixed materials or final coated parts as well as maintenance‐friendly constructions, and significantly influence the design. The VDI 2230–1 forms the basis for the dimensioning of such joints in mechanical engineering. To meet tolerance requirements in the assembly of components and subassemblies and to enable a efficient production process, the holes for the connections are often designed as oversized round or slotted holes. However, the increased nominal hole clearance is not taken into account in the calculation steps R0 to R13 for the calculation of highly stressed bolted joints with one cylindrical bolt according to VDI Guideline 2230–1, which leads to overdimensioning or auxiliary constructions. The practical verification often can only be supported by cost‐intensive individual case studies based on laboratory tests. The investigations shown in this paper aim on the determination of the pressure distribution in the interface, the bolt resilience as well as the influence of the hole geometry on the plate resilience to create a well founded data basis for the development of an analytical calculation model according to VDI 2230–1 for bolted connections with increased nominal hole clearance. [ABSTRACT FROM AUTHOR]

Most of the frame structures in mechanical equipment are connected by bolts, and the non-uniform pretension among the bolts will have an obvious impact on the vibration characteristic parameters of the frame structure. In this paper, semi-analytical modeling and vibration analysis of a frame structure considering non-uniform pretension of bolts are carried out based on the Timoshenko beam theory and Rayleigh-Ritz method. Specifically, a method is proposed to decompose the frame structure into several substructures and model them respectively, and further the coupling springs are applied among the substructures. Through the vibration test of a beam lap structure with a bolted joint, the analytical expressions between bolt pretension and bolted joint stiffness and damping parameters are obtained. Moreover, the method of simulating the non-uniform pretension among each bolted joint is proposed. Considering the external factors such as reinforcing rib structures and flexible rod exciter, and a complete semi-analytical dynamic model of the bolted frame structure introducing the non-uniform pretension is further established. A case study is carried out on a frame structure that contains four connecting bolts with non-uniform pretension. The natural characteristics of the frame structure are solved by using the developed modeling method, and the rationality of the analysis results is verified by experiments. Based on this, the increasing trends of the resonant frequencies and the resonant response of the frame structure under different pretension conditions are analyzed from two aspects of experiment and simulation. [ABSTRACT FROM AUTHOR]

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

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company 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.)

Topological insulators with high spin–orbit coupling and helically spin-momentum-locked topological surface states (TSSs) can serve as efficient spin current generators for modern spintronics applications. We used the industrial-friendly DC magnetron sputtering technique to fabricate magnetic heterostructures consisting of Bi2Te3 (BT) as a topological insulator and Co60Fe20B20 (CFB) as a magnetic layer and studied the temperature-dependent spin pumping, utilizing out-of-plane ferromagnetic resonance spectroscopy. These results demonstrate that the effective spin-mixing conductance is significantly affected by the contribution of two-magnon scattering (TMS). It is found that the TMS-free effective spin-mixing conductance increases with decreasing temperature. Additionally, results from magneto-transport measurements indicate that the surface coherence length of BT is in accordance with the temperature-dependent effective spin-mixing conductance. This enhancement of effective mixing conductance correlated with the enhancement in the contribution of the TSSs as evaluated using the weak-anti-localization effect. This study provides a deeper understanding of the temperature-dependent spin dynamics in sputtered BT/CFB heterostructures which can serve as a guide for further exploration of such bilayers for topological-based spintronic applications. [ABSTRACT FROM AUTHOR]

Pre-tightening torque has a significant impact on the performance of a bolt-clamped high-frequency piezoelectric ultrasonic transducer widely used in wire bonding. To develop a vibratory response-based method for the determination of optimal pre-tightening torque, the vibration amplitude signals of the transducer under different excitation conditions were monitored, and the characteristic parameters of the response, involving the resonance frequency, settling time within the initial transient response, and vibration amplitude of the steady-state stage, were extracted. Based on a series of in-depth tests, analyses, and discussions, the influences that the pre-tightening torque has on the vibratory response properties were investigated. Then, the experimental measurement and the random forest method were combined to determine the optimal pre-tightening torque. The performance test results show that the developed method can give the optimal pre-tightening torque according to the desired vibrational response properties, and it is feasible, effective, and reliable as well as improves the adaptability and flexibility of the high-frequency ultrasonic transducer in the application. [ABSTRACT FROM AUTHOR]

Wind load is one of the main control loads of transmission tower-line systems. Numerical simulation is the main method for studying the structural wind-induced response. The establishment of a refined transmission tower simulation model is the basis for accurately analyzing the dynamic response of a transmission tower-line system under a wind load. This paper first considered the mechanical properties of bolted joints under cyclic loading and established a transmission tower-line system model considering the joint effects. Then, the wind load was generated by the harmonic superposition method, and the wind dynamic time-history analysis of the tower-line system was conducted. The influence of the joint effect on the wind-induced response of the transmission tower-line system was studied, and the effects of turbulence intensity and wind attack angle on the bolted joint slip effect were discussed. The results showed that the joint effect significantly increased the displacement response of the transmission tower subjected to wind loads and affected the normal service performance of the tower-line system. When the turbulence intensity is 10%, the top displacement of the tower model considering the joint effect is approximately 2 times that of the ideal rigid frame model. After considering the joint effect, the additional P − Δ effect caused by the increased displacement resulted in an increase in the stress of 75.6% members, and the maximum stress of the main member was located near the upper diaphragm of the tower leg. Therefore, considering the joint slip effect in angle steel transmission towers can improve the accuracy of the dynamic response analysis of transmission lines. [ABSTRACT FROM AUTHOR]

The dowel bearing capacity is a fundamental metric for assessing the performance of bolted connections. In this research, we examined the dowel bearing strength of bamboo scrimber across various load-to-face grain angles. Seven groups of specimens, each comprising 10 units, were subjected to testing. Yield strength was determined using the ASTM-D5764 5%D offset method, revealing a pattern where strength initially decreases with increasing grain angle, reaching a nadir at 60°, before rising again. This indicates that grain angle significantly affects both strength and stiffness. Analyzing the failure modes, load–displacement curves, and key mechanical properties of the specimens, comparing the dowel bearing strength trends across grain angles in different bamboo and wood materials. Discrepancies between theoretical predictions and experimental results were also evaluated. Based on these findings, we proposed a calculation formula for dowel bearing strength at various grain angles, tailored to bamboo scrimber. [ABSTRACT FROM AUTHOR]

Highlights Carbon Fiber Reinforced Polymer (CFRP) Hybrid Bonded/Bolted (HBB) joint structures are distinguished for their superior jointing performance among current mechanical joint systems, making them a favored option for mechanical joints. These structures are characterized by many structural parameters, with the relationship between these parameters and jointing performance being notably complex. Additionally, the laminate's brittleness and the uneven distribution of bolt loads in multi‐bolt joint structures impair the overall jointing performance. To investigate the impact of structural parameters on the uneven load distribution within CFRP HBB joint structures and improve their jointing performance, a finite element analysis (FEA) model grounded in 3D Hashin failure criterion is developed. Validation of the model with experimental data confirmed the uneven load distribution among bolts in multi‐bolt joints. The study elucidated the influence of changes in structural parameters (overlap length, bolt‐hole spacing, and clearance fit) on the uneven load distribution and the connection strength of CFRP HBB joint structures. A negative correlation is found between the unevenness of load distribution and connection strength, offering insights for enhancing and researching connection strength in CFRP HBB joint structures. Developed a FEA model based on the 3D Hashin failure criterion for CFRP Bonded‐Bolted joints. Identified key factors affecting HBB joint load distribution and jointing performance. Evaluated the impact of overlap length, bolt‐hole spacing, and clearance fit on CFRP joints. Suggested design optimizations for enhancing the performance of HBB joints. [ABSTRACT FROM AUTHOR]

In the literature on rotating machinery, many articles discuss the analysis of various rotor and bearing defects, including both sliding and rolling bearings. Defects in the rotor supporting system are investigated much less frequently. In rotor-bearing-supporting structure systems, where there are couplings between the individual sub-systems, damage to the supporting structure can significantly impact the dynamic properties of the entire machine. The authors of this article have, therefore, focused on analysing the defects that can occur in the supporting system of the rotor and bearings. This article presents the results of a numerical analysis of two common defects in the supporting structure: cracks in the bolted joints attaching the machine body to the foundation and a decrease in foundation stiffness. The research object was a test rig that accurately reproduced the dynamic phenomena occurring in rotating machinery, such as vapour and gas turbines. In the numerical model of the rotating machine, a three-dimensional linear model of the supporting structure was combined with a beam model of the rotor line via a nonlinear fluid film-bearing model. The developed model allowed for the analysis of two different failures in the supporting system over a wide range of rotational speeds. The calculations showed that damage to the supporting structure can significantly impact the dynamic characteristics of the entire rotating machine. [ABSTRACT FROM AUTHOR]

The detection of bolt loosening in key components of aircraft engines faces problems such as complex and difficult-to-establish bolt loosening mechanism models, difficulty in identifying early loosening, and difficulty in extracting signal features with nonlinear and non-stationary characteristics. Therefore, the automated structural bolt micro looseness monitoring method using deep learning was proposed. Specifically, the addition of batch normalization methods enables the established Batch Normalized Stacked Autoencoders (BNSAEs) model to converge quickly and effectively, making the model easy to build and effective. Additionally, using characterization functions preprocess the original response signal not only simplifies the data structure but also ensures the integrity of features, which is beneficial for network training and reduces time costs. Finally, the effectiveness of the proposed method was verified by taking the bolted connection structures of two key components of aircraft engines, namely bolt connection structures and flange connection structures, as examples. [ABSTRACT FROM AUTHOR]

Bolted connections for built-up cold-formed sections are studied using different section configurations, gusset plates, and bolt arrangements. This paper presents the study of a connection between beam and column in light-weight steel frames with spans ranging between 8.0 and 12.0 m and a maximum height of 6.0 m that are used in agricultural sheds. The cross section of the beam and column is a novel built-up cold-formed cross section. A total of eight connections were tested and studied. The purpose of the study is to determine the effect of serval factors on the moment capacity and failure modes of the connection. The experimental study considered the effects of different shapes of tie plates, numbers, and spacings of bolts, as well as the effect of strengthening angles with different numbers of bolts in the connections. The experimental results showed that the failure modes in all connection types were due to a local failure in the connecting parts. The experimental results revealed that the configuration type has a great influence on the moment capacity of the connection. [ABSTRACT FROM AUTHOR]

Hybrid interference‐fit bolted‐bonded (HIBB) composite joint has a wide application prospect in improving bearing capacity of the hybrid structure. In order to deeply understand its load sharing mechanism, an analytical stiffness prediction model of HIBB composite joint was established, considering the influence of interference‐fit percentage, preload, friction coefficient, adhesive property, material performance, secondary bending moment and other parameters. Corresponding experiments were carried out to determine the experimental secondary bending moment coefficient, and the accuracy of the model was further verified. Research on HIBB composite joint shows that the hybrid form increases the adhesive failure displacement but has no effect on failure load. Before adhesive failure occurs, bolted joint stiffness is small and bolt load will increase suddenly to bear the load loss caused by the adhesive failure. It is further found that load‐sharing ratio of the bolt and total load of the structure increase with the increase of interference when adhesive failure occurs. Preload and friction coefficient have limited influence on total load of the structure at this moment, but have great influence on the bearing capacity of pure bolted structure after adhesive failure. The adhesive properties have great influence on the bearing capacity of bonded joint. Low modulus high strength adhesive can improve the load‐sharing ratio of bolt and enhance the bearing capacity by reducing the overall stiffness of the structure. Bearing mechanism of the two joint forms in the hybrid one was fully revealed, which provides a theoretical method for the application of HIBB composite joint. Highlights: An analytical stiffness prediction model of HIBB composite joint was established to deeply understand its load sharing mechanism.Load sharing mechanism analysis and parametric research for the two joint forms were carried out and influences on stiffness were obtained.Low modulus high strength adhesive can improve the load‐sharing ratio of bolt by reducing the overall structure stiffness.Bearing mechanism of the two joint forms in the hybrid one was revealed. [ABSTRACT FROM AUTHOR]

Highlights Assessing the mechanical properties of CFRP and aluminum specimens exposed to hygrothermal aging is vital. Moreover, it is important to develop strategies to improve these properties. This study examines the influence of fullerene and Single‐Walled Carbon Nanotubes (SWCNT) on the fatigue life and static strength of bonded and bonded/bolted joints. The research concentrates on composite‐to‐composite and composite‐to‐aluminum substrates under three‐point bending tests, both prior to and after hygrothermal aging. The samples were classified into four groups: (1) neat specimens, (2) specimens with added fullerene, (3) specimens containing SWCNT, and (4) specimens with a blend of 50% SWCNT and 50% fullerene.The findings indicated that the optimal nanoparticle ratio for bonded joints differs from that for bonded/bolted joints. Incorporating nanoparticles into the adhesive enhanced the fatigue life of single lap joints (SLJs), particularly in samples with mixed particles and SWCNT. In some instances, nanoparticles intensified the effects of hygrothermal conditions, further increasing fatigue life. The incorporation of nanoparticles and the use of bonded/bolted joints significantly enhanced joint strength, with the combination of both yielding the best results. This study improves the understanding of aging in adhesive and hybrid joints, particularly in dissimilar configurations, and offers insights into their performance under various environmental conditions. Study examines fullerene and SWCNT impacts on CTC/CTA joint strength and fatigue. Optimal nanoparticle ratios differ for bonded and bonded/bolted joints. Nanoparticles reduce moisture absorption, aging damage, and increase failure load. Nanoparticles enhance fatigue life, varying by type, volume, load, and joint. Incorporating nanoparticles significantly improves joint strength. [ABSTRACT FROM AUTHOR]

Petroleum bolts are important connection points for various key parts of oil wellhead blowout preventers. Bolted connections are prone to loosening, deformation, defects, and even fractures in the oil well environment, which can cause adverse consequences to the wellhead blowout preventer. Ultrasonic testing is a nondestructive testing method widely used in metal material testing. This experiment uses M10 bolts as test samples, then will use wire cutting equipment to simulate the damage of bolts in a cutting form, simulate the prefabricated cracks of bolts, and then use piezoelectric chips pasted on the bolt head to collect ultrasonic signals. Three different devices, including ordinary ultrasonic emission and reception equipment, nonlinear ultrasonic, and UA-360 ultrasonic wave detection equipment, will be used, and different load forces will be applied to the bolts using an electronic universal tensile testing machine, By collecting ultrasonic signals before and after prefabricated bolt cracks, as well as under different axial stresses, the relationship between external load and prefabricated bolt cracks on accelerating bolt failure can be identified. And at the same time, the macroscopic morphology and microstructure of the bolt fracture were analyzed. Through the analysis of the bolt cross-section image, it can be concluded that the failure of the bolt is all affected by the prefabricated cracks. [ABSTRACT FROM AUTHOR]

Understanding the shear characteristics and acoustic emission features of bolted joints is crucial for the optimization of support systems and disaster early warning. In this paper, a series of shear tests on rock joints using both full-length anchorage and partial anchorage methods were conducted. The evolving patterns of shear mechanical characteristics and acoustic emission features of bolted rock joints were obtained, elucidating the influence of anchorage methods and revealing the shear failure mechanisms of joints under different anchorage lengths. The results indicate that the "pin effect" of the bolt can be rapidly mobilized in the full-length anchorage compared to the partial anchorage method. The full-length anchorage exhibits higher peak shear stress and fracture shear stress, with maximum differences of 0.38 MPa and 0.08 MPa, respectively, when contrasted with the partial anchorage method. The deformation range of bolts in the partial anchorage method approximately doubles that observed in the full-length anchorage. Acoustic emission feature parameters exhibit a good correspondence with shear stress curves, and their evolution suggests that the most significant damage to bolted joints occurs at the shear stress peak, with the highest energy release observed when bolts fail. Under both partial anchorage and full-length anchorage, with an increase in normal stress or JRC, the b of bolted joint acoustic emissions gradually decreases. Compared to the partial anchorage method, the full-length anchorage demonstrates a higher maximum Hit rate, along with lower maximum energy release, implying more intense interaction between bolts and surrounding rock in the full-length anchorage, resulting in greater damage under the same conditions, whereas the deformation range of bolts is smaller, and the energy released upon failure is lower in the full-length anchorage. Highlights: A series of shear tests on rock joints using full-length and partial anchorage methods. Investigated the effects of anchorage lengths, normal stress, and joint surface roughness on shear behavior and acoustic emissions. The effects of the anchorage lengths on the fracture behavior of bolted joints was revealed. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the mechanical performance of bolted joints used in silos for storing bulk materials. In particular, we investigated the effectiveness of three types of bolted joints: one without reinforcement, one with angular reinforcement, and one with squared reinforcement. Our analysis involved the use of the finite element analysis sub-modeling technique, which allowed us to construct a large finite element model with shell elements and a sub-model with solid elements. By analyzing the stress state of each joint, we were able to determine the contact state and contact pressure of the bolted joint. Our findings showed that bolted joints reinforced with triangular and square plates were effective in maintaining contact pressure, even under high-stress conditions. This study provides valuable insights into the design of bolted joints used in silos, which can help ensure their reliable and safe operation. [ABSTRACT FROM AUTHOR]

This study establishes a finite element model based on the Iwan model to accurately characterize the force–displacement relationship and energy dissipation in bolted joints under small-amplitude tangential displacement. The force–displacement behavior of the Iwan model is transformed into a stress–strain relationship using a hybrid hardened intrinsic model. A subroutine developed with UMAT and UHARD is used to simulate the elastic–plastic behavior of the Iwan model during surface contact in the finite element model. Three-dimensional modeling and joint simulation are conducted using ABAQUS software. Experimental data verify the model's validity, and the effects of multiple factors on the bolted bonding surface are analyzed. The influence of friction coefficient, cyclic displacement amplitude, and preload on the force–displacement relationship of the bolted bonding surface is explored. Polynomial interpolation of the loading and unloading curves is applied to investigate the energy dissipation phenomenon. Results show that the finite element method can effectively reflect the hysteresis and energy dissipation behavior of the bonding surface. Increased friction coefficient and preload improve residual stiffness and energy dissipation capacity, while larger cyclic displacement amplitudes increase energy dissipation but have a minimal effect on residual stiffness. [ABSTRACT FROM AUTHOR]

Bolted connections are a common feature of connection in mechanical structures, employed to secure connected parts by tightening nuts and providing preload. The preload is susceptible to various factors leading to potential bolt loosening. The acoustoelastic theory is the most common measure of a bolt structure's stress. The present study investigates the relationship between the inherent properties of a structure and its acousticelastic properties. The modal response of the bolted structure under different preload forces is studied by translating the acoustoelastic relationship of the structure into an analysis of its intrinsic properties. The modal analysis reflects the relative change in wave velocity to be determined implicitly based on the eigenfrequencies of the structure. A frequency formulation of classical bolted structures based on acoustoelastic theory is presented in this paper to conduct the intrinsic characteristic analysis of bolted structures. The COMSOL5.4 simulation results are under the acoustic elasticity coefficients for ultrasonic wave propagation in bolt structures, as predicted by the acoustic elasticity theory, and the present solutions are compared with those available in the literature to confirm their validity. A systematic parameter study for bolted structures under the varying preloads with different material parameters, Lame elastic constants, Murnaghan third-order elastic constants, and structural parameters are presented. These results may serve as a benchmark for researchers in this field. [ABSTRACT FROM AUTHOR]

Transmission towers in service are highly susceptible to corrosion caused by environmental conditions. It is crucial to assess the residual load capacity of corroded angles in transmission towers. In this study, corrosion at the connection of angels was simulated by local damage using a mechanical cutting method, and compression tests and numerical simulations were performed to investigate the load capacity of corroded angles. A total of 24 angles were designed and tested in the experiments, and the parameters considered included the location and thickness of damage and slenderness. The local damage was designed on the loaded or non-loaded legs, with slendernesses of 80 and 140, and a thickness of damage of 1 mm and 2 mm. The residual load capacity, failure modes, and strain of the angles were analysed based on experimental results. Furthermore, corrosion was simulated by reducing the local thickness of angles using ABAQUS. The accuracy of numerical models was verified after comparing the numerical results with experimental data. Based on the verified model, parameter analysis was conducted, in which the slendernesses was extended to 100 and 120, and the local damage thickness was also set to be 0.5 mm and 1.5 mm to quantitatively study the influence on the residual load capacity. The tests results showed that with the damage depth at the ends of the angle increased, and the load capacity of the angle decreased by up to 6.7%. Finally, a design equation for calculating the residual load capacity of corroded angles was proposed using the numerical results. By comparing the design equation, experimental results, and load capacity calculated per existing standards, it was found that the load-bearing capacity of corroded angles can be accurately predicted by the equation. [ABSTRACT FROM AUTHOR]