Pre-tightening Force Research Articles

Design, Analysis, and Optimization Testing of a Novel Modular Walking Device for Pipeline Robots

This article investigates the limitations associated with traditional wheel-type pipeline walking devices, which are characterized by a single movement mode and an inability to navigate complex or irregular pipeline structures. A modular walking device (MWD) designed for pipeline robots was developed utilizing structural and mechanical analysis techniques. The reliability of the mechanical analysis was validated through single-factor dynamic testing. To analyze and optimize the factors influencing the maneuverability and obstacle-crossing capabilities of the MWD, a three-factor, three-level orthogonal testing method was utilized. The factors examined included the rotational speed of the walking wheel (RS), the pre-tightening force of the wheel brackets (PF), and the height of the annular obstacle (OH). The evaluation metrics used were the slip rate and passability. The results indicated that a parameter combination of RS at 70 rpm, PF at 30 N, and OH at 10 mm produced a slip rate of 11.6% ± 1.5%. During the obstacle traversal process, the remainder of the device maintained a safe distance from the obstacles, with only the walking wheel making contact. The verification testing also confirmed that the MWD is capable of executing three distinct modes of motion: rectilinear, rotational, and helical. The MWD designed and developed in this study can switch between multiple motion modes and successfully overcome obstacles within 15 mm, providing a new equipment for universities to enhance mechanized pipeline detection technology.

Influence of bolt creep induced pre-tightening force relaxation on dynamic response of the bolted joint system

The bolted joint is an important link that affects the accuracy maintenance of the heavy-duty machine tool. Due to bolts of the crossbeam are under a preload of several hundred kN for an extended period, the bolt gradually creeps and elongates as the machine tool's service time increases. This relaxation of the preload results in a degradation of the bolted stiffness, weakening the dynamic response of the bolted joint system. To reveal that the degradation law of crossbeam bolting performance of the heavy-duty machine tool induced by bolt creep, based on the Norton-Bailey(NB) model, a method for analyzing the creep of bolts with precision threads is proposed, and the influence of thread geometry and friction coefficient on the creep stress relaxation of bolts is studied. Considering the interface contact, an interface contact stiffness model is derived based on fractal theory. The dynamic equation of the bolted beam system is established using the Matrix27 stiffness matrix. The dynamic response of the bolted system, resulting from the degradation of interface stiffness due to bolt creep, is analyzed. The results show that the stress relaxation of bolt creep is not only related to creep parameters, but also related to the mate-thread interaction. The dynamic model with Matrix27 stiffness matrix is comparable to experiment in calculation accuracy and efficiency, which provides technical guidance for machine tool dynamics analysis and effectively solves the scientific problem of beam bolting performance degradation during the service of heavy-duty machine tools.

A reasonable method to reduce the volume of the WC anvil.

With the continuous development of the diamond industry, the China-type cubic press (CCP) has gradually become larger. As a result, the volume of the tungsten carbide (WC) anvil has been increased. Considering that the WC anvil is sintered, a larger volume will deteriorate sintering quality, which could facilitate the formation of cracks during its operation. One feasible way to reduce the volume of the WC anvil is to decrease its diameter and height. Along these lines, in this work, by performing finite element simulations, it was found that a reduction in the diameter of the WC anvil would increase the von Mises stress (VMS) during the synthesis process, as well as reduce the service life of the WC anvil and the ultimate pressure of the CCP. At the same time, a smaller diameter of the WC anvil would cause a significant increase in the VMS of the base steel block, exceeding its yield limit. In addition, a reduction in the height of the WC anvil would lessen the VMS during the synthesis process, and the VMS of the base steel block will also decrease. A reduction in the height of the WC anvil will decrease the pretightening force on the WC anvil, thereby reducing its lateral support effect. When the interference fit was increased from 0.6 to 0.8mm and the steel ring angle was changed from 1.5° to 1.1°, the pretightening force on the low WC anvil was similar to the pretightening force on the original WC anvil. Our work provides valuable insights for effectively reducing the volume of the WC anvil.

Influence of pre-tightening force on bearing capacity of composite cylinder

Influence of pre-tightening force on bearing capacity of composite cylinder

Study on Pretightening Loss Effect of Bolt Support in Deep Soft Rock Roadway

The magnitude of pretension force serves as an important indicator of the effectiveness of anchor bolt active support and is one of the significant factors influencing the stability of tunnel surrounding rock. Therefore, in practical engineering, it is crucial to establish the relationship between pretension torque and pretension force. However, current research in this field has some limitations. With a specific mine in western China as the engineering background, this paper first analyzed the influence factors of surrounding rock deformation and failure, established a mechanical model for pretension structure of anchor bolt support, and derived the quantitative relationship between pretension torque and pretension force based on hypothetical conditions. Finally, it proposed the loss effect of anchor bolt support and modified the pretightening loss coefficient for engineering application. The research results show that the actual pretightening force of anchor support is lower due to the influence of deep soft coal seam, which leads to failure of coal pillar under mining stress. The loss effect of surrounding rock on pretightening force was represented by a coefficient k, and the modified value of the coefficient was calculated as 0.19∼0.43. By applying the modified relationship between pretightening torque and pretightening force, it was found that the actual pretightening torque of 300 Nm applied to 11307 return air roadway effectively controlled surrounding rock deformation and failure, with coal pillar displacement less than 120 mm.

Seismic Performance Evaluation of Traditional Chinese Mortise-Tenon Frame Infilled with Friction Dissipative Window Frame

ABSTRACT This paper presents a new form of window frame that employs a friction dissipative connection. The design is informed by a structural analysis of the sill window in traditional wooden structures and inspired by friction dissipative mechanisms. By considering the frictional wear of the friction block, a more accurate formula for calculating the frictional torque is derived and its accuracy is verified. Additionally, a finite element model of the sill window-wooden frame system is established and verified using experimental data. Then a further finite element model of the sill window-wooden frame system with the friction dissipative window frame is established and analyzed, and the effectiveness of the reinforcement scheme of the friction dissipative connection is verified. The analysis shows that compared to the sill window-wooden frame system, the load-carrying capacity and energy dissipation of the sill window-wooden frame reinforced with the friction dissipative window frame are significantly improved. When the bolt pre-tightening force is 100 kN, the peak load and stiffness of the sill window-wooden frame system reinforced with the friction energy dissipation window frame are increased by 2.7 and 2.57 times, respectively, compared to the sill window-wooden frame, which can effectively prevent the seismic damage of ancient wooden structures.

Investigations on the modal vibration caused by bolted joint interface contact in the rotor-AMBs systems: Modelling and experimentation

Rotor-active magnetic bearings (rotor-AMBs) systems nowadays have been widely used in fluid machinery and the impeller and the shaft are commonly connected by bolted joint. However, when a certain pre-tightening force is applied to the bolted joint and the interface contact between the shaft and the impeller is formed, causing flexible modal vibrations when rotor is levitated. The mechanism of this modal vibration needs to be revealed to ensure stable operation of the machine. In traditional modelling, the effect of the interface contact is equated to an additional stiffness matrix by massless spring units, whose certain contact stiffness is uniformly distributed over the interface. Particularly, the calculation of contact stiffness and the effect of AMBs are neglected, resulting in the inaccurate response compared to experiments. Based on traditional modelling, we consider that there is partial separation in the contact interface due to the AMBs supporting and a novel additional stiffness matrix related to contact status is proposed by calculating the real-time contact area. The contact stiffness is calculated by microscopic contact model based on fractal theory and surface topography measurement. Finally, numerical simulation shows that the interface contact influences the system robustness and the unstable mode is excited. The increase of pre-tightening torque and contact radius both will increase the steady vibration amplitude, with the former being the major contributor. Moreover, the influence and order of the vibration are quantitatively validated by the experiments.

Acoustic and Vibration Response and Fatigue Life Analysis of Thin-Walled Connection Structures under Heat Flow Conditions

Thin-walled connection structures are commonly used in the hot-end components of aerospace vehicles. Large deflection nonlinear responses and fatigue failure occur due to their discontinuous mass distribution and prominent cross-sectional changes under the action of complex thermal, aerodynamic, and noise loads. A thermoacoustic fatigue test was carried out to obtain the acoustic and vibration responses and fatigue life changes of the connection structure under heat flow conditions in engineering applications. The high-temperature acoustic fatigue test system of aviation thin-walled structures was used, taking the high-temperature alloy thin-walled plate-load-bearing frame bolted connection structure as the research object. As a result, the vibration response and fatigue life under different thermoacoustic loads were obtained. The contact finite element method was used to simulate the connection pre-tightening force, and the coupled finite element/boundary element method was used to calculate the acoustic and vibration response of the heat flow conditions. The changing rules of the frequency response peak value at the critical point of the thin-walled connection structure under the effects of different temperature fields, fluid fields, and sound fields were obtained through the processing and analysis of the calculation results. Considering the structural vibration fatigue damage mechanism, this study employed an improved rainflow counting method to compute the rainflow circulation matrix (RFM) and rainflow damage matrix (RFD) of the vibration stress time history at critical points within the structure framework. Said method was combined with Miner’s linear cumulative damage theory to estimate the fatigue life under various thermal-fluid-acoustic coupled loads. A comprehensive analysis validates the accuracy of the established numerical simulation calculation model in identifying critical connection points within structures subjected to pre-tightening forces. This model effectively characterizes thermal, aerodynamic, and acoustic loads on high-temperature alloy thin-walled-load-bearing frame bolted connection structures. It delineates the relationship between vibration response and fatigue life while assessing the impact of three distinct load parameters.

Finite element model analysis of long-term performance of composite anchorage based on double-material parameters

Carbon fibre-reinforced polymer (CFRP) tendons demonstrate the advantages of light weight, high strength, and superior corrosion resistance and have broad application prospects for long-span cable structures. However, given the low transverse shear strength of CFRP tendons, how to achieve long-term and reliable anchorage for CFRP tendons is a critical issue. The long-term performance (LTP) of a novel composite anchorage for CFRP tendon was assessed in this study. Then, a finite element model (FEM) with double-material creep parameters was established to reliably model the LTP experiment according to the creep parameters of the bonding medium and CFRP tendon. Finally, the effects of the free section tendon length, pre-tightening force, over-tensioning force, and elastic modulus of the bonding medium were analysed using the established FEM with double-material creep parameters. Results revealed no visible damage to the CFRP tendon and anchorage after the LTP experiment. The maximum tendon slippage was 0.054 mm, and the residual load ratio was 0.826. These phenomena indicate that the novel composite anchorage has excellent LTP. The FEM modelling results based on double-material creep parameters were in good agreement with the experiment results. The residual load ratio calculated by the FEM was 1% lower than the experimental value. Through the parameter analysis, the residual load ratio of the specimen was effectively improved under longer free section tendon condition, but tendon slippage increased to a certain extent. In addition, the LTP of the composite anchorage can be effectively improved by appropriately decreasing pre-tightening force and over-tensioning force. When the over-tensioning force was 1.4 times the test load, the tendon slippage was reduced by 34.2%, and the residual load ratio increased by 4.8%. The greater elastic modulus of the bonding medium in the range of 2.1 GPa–3.1 GPa, the worse the LTP of the composite anchorage.

Experimental and numerical investigations of a staged energy dissipation device

Energy-dissipating devices (EDDs) are widely used in building structures to mitigate seismic disasters. This study designed a fully assembled friction-metal series damper which is one kind of the staged energy dissipation devices (SEDD). Quasi-static tests were conducted to examine the behaviour of the SEDDs. The influence of factors such as the configurations of the restrainers, pre-tightening force, and material of the metal strip module was investigated. The work behaviour of the SEDD consists of three stages: elastic, frictional energy dissipation, and metallic elastic–plastic energy dissipation stages. The experimental results verified the effectiveness of the predicted working mechanism and showed that the bearing capacity and energy dissipation of the SEDD increased with the configuration of the restrainers, pre-tightening force, and yield strength of the metal strip module. The experiment also showed that the rotation of the outer plates caused an unexpected force mode in the metal strip module. Subsequently, numerical models of the test specimens were built, and good agreement was observed between the numerical simulations and test results for the hysteresis performance, loading capacity, and stress distribution. To further improve the mechanical properties of the SEDD, an optimised model was established and studied. The SEDDs with optimised strip shapes and constraint conditions of the outer plate exhibited better mechanical performance, and their load capacities increased by 11 % and 41 %, respectively.

Experimental and numerical studies on friction energy-dissipating combination chord of staggered truss

Staggered truss framing systems have the problem of insufficient energy dissipation capacity in high intensity areas. To improve this situation, this paper proposes to replace the top chord of the staggered truss with a combination chord for frictional energy dissipation. Two groups and a total of four 1:2 scaled friction energy-dissipating combination top chord specimens were designed and fabricated, and hysteretic performance tests were carried out on them under low cycle reciprocating loads. It was investigated how high-strength bolt pre-tightening force and bolt layout affected the capacity of the combination chord to dissipate energy. The experimental results show that the hysteresis curve of the combination top chord for friction energy dissipation almost presents an ideal rectangle, and its energy-dissipating capacity is very strong. The combination top chord's capacity for friction energy dissipation increases with the increasing pre-tightening force of the high-strength bolt, but its stability for energy dissipation decreases. When the bolt layout is the staggered arrangement of single and double bolts, the initial energy dissipation and cumulative energy dissipation are weaker than that of the uniform arrangement of double bolts. Then, the friction energy-dissipating staggered truss with a sliding bottom chord was proposed to improve the load state of the diagonal web member in the staggered truss. The numerical simulation results show that the overall energy dissipation capacity and lateral bearing capacity of the staggered truss with the bottom chord sliding are 4.0% and 24.5% higher than those of the staggered truss with the top chord sliding.

Research on performance state evaluation of circuit breaker energy storage spring based on intelligent algorithm

The performance state evaluation method of circuit breaker energy storage spring mainly judges its performance state indirectly by measuring the pre-tightening force or pre-pressure of the spring. However, there may be some errors in this indirect measurement method, which will affect the accuracy of the evaluation results. Therefore, the performance state evaluation based on intelligent algorithm is proposed. Select the evaluation characteristic quantity of performance state, calculate the energy storage spring impulse according to the momentum theorem, and obtain the pressure value of the closing energy storage spring through the pressure sensor as the evaluation quantity reflecting the energy storage spring performance state. The BP neural network is established, and the fireworks algorithm is applied to the BP neural network to optimize the initial weight and threshold, so as to realize the performance state evaluation of energy storage spring based on BP neural network. The experimental results show that the spring energy release speed of the proposed method is in the range of 0 - 1.0m/s, and the estimated spring pressure value is basically consistent with the actual value.

Measurement and assembly methods for bolted flange joints using three-dimensional digital image correlation

Bolted flange joints are extensively used in pressure vessels and piping equipment. The assembly coaxiality accuracy and bolt pre-tightening force are particularly important in causing the risk of seal and leakage failure. This paper proposed a novel non-contact measurement and assembly adjustment method to reduce the coaxiality angle deviation efficiently. The flange joint is first bolted according to standard flange joint assembly guidelines and then adjusted using the proposed method. In the proposed method, the surface deformation and the coaxiality of the flange are evaluated using a 3D-DIC (three-dimensional digital image correlation) technique; RMS (root mean square) of the surface deformation is used to drive the correction of the bolts to further reduce the coaxiality angle deviation. Compared with existing bolting patterns, the established measurement and assembly adjustment method, which combines 3D-DIC measurement and adjustment based on RMS, can effectively reduce the coaxiality angle deviation. The experiments using a correction strategy demonstrated that the coaxiality angle deviation is reduced by 48.9 % and 60.1 % on average compared with the well-known star bolting pattern and modified star bolting pattern provided by ASME PCC-1, respectively, and even by 30.6 % and 51.9 % compared with their rotational pass patterns. Further experiments with an iterative strategy showed that the coaxiality angle deviation could be reduced by around 70 % and 75 %, tending to be stable around 0.01°–0.035°, after only 5 iterative adjustments.

Analysis of the Support Failure Mechanism Caused by Bolt Pre-Tightening Force Loss

The pre-tightening force loss (PTFL) of bolts is an important but underestimated cause of roadway instability. In mine anchorage systems, the actual pre-tightening force of bolts is only 50% to 80% of the design value. Through a case study at Xiahuo Coal Mine, it was found that the essential causes of PTFL are the increasing friction coefficient between supporting units controlled by factors such as pre-tightening torque levels, pre-tightening cycles, and surrounding rock roughness. This study investigates the behavioral characteristics of PTFL and its influence on surrounding rock failure in roadways. This research reveals a linear correlation between pre-tightening force and torque, with an average torque conversion coefficient of approximately 0.19. However, the PTFL increases with higher levels of pre-tightening torque, increasing pre-tightening cycles, and rougher surrounding rock conditions. For every 30 N·m increase in pre-tightening torque, the PTFL increases by approximately 1.67 kN. Reducing the PTFL can expedite the stress redistribution process and shorten the self-stabilizing period of the roadway by approximately 10 days, thereby enhancing the active supporting potential of bolts.

Seismic behavior of a new fabricated concrete grating composite wall structure in rural residences: Shaking table test and finite element analysis

To promote the application of prefabricated concrete structures in the field of rural residences, this paper proposes a new fully fabricated concrete grating composite wall structure (FFCGCW). A 2:3 scaled single-story model with door and window openings was designed, and a shaking table test was carried out to study the seismic performance of the FFCGCW structure. Three types of seismic waves were selected to analyze the failure modes, dynamic response, displacement response, strain response, and acceleration response of the structure under four peak ground accelerations (PGAs). The experimental results indicated that the FFCGCW structure had a large stiffness and could work in an elastic state at PGA = 0.4 g. At PGA = 0.8 g, the maximum inter-story drift was 1/600, and the natural frequency decreased by 9.4 %. The structure just entered a plastic state, and no overall failure occurred when loaded to 0.8 g. The cracks mainly occurred on the concealed beam at the upper end of the window, the corner of the door opening, the floor slab, and the column base, but they did not continue to develop and no collapse occurred. Compared to cast-in-situ concrete structures, FFCGCW structural components use bolt-connected keyed joints, which are convenient for construction and have similar seismic performance. During the earthquake, the bolt gaskets constantly deformed, the pre-tightening force of the bolt decreased, and the keyed joints allowed for mutual displacement between structural components to dissipate energy. Meanwhile, a simplified shell-element finite element (FE) simulation method was proposed for the grating wall, and the experimental data was verified by the FE analysis, with errors within 10 %.

Research on hysteretic performance of a semi-rigid energy dissipation connection for precast cladding panels

A novel semi-rigid energy dissipation connection (SEDC), capable of transitioning the precast cladding panel from a rigid connection to a flexible connection with the primary structure as the seismic action increases, is proposed in the present study. The combination of the bending part and friction part endows the connection with the ability to provide adjustable sliding force and sufficient energy dissipation for the precast cladding panel. The design methods of SEDC, including the elastic stiffness, the yield force, the yield displacement, and the bear capacity, are proposed, followed by a coordinated design method between the precast cladding panels and the primary structure based on SEDC. Fourteen SEDC specimens are designed and tested under monotonic and cyclic loading tests to investigate the semi-rigid workability of SEDC and to evaluate the influence of design parameters of the bending and friction parts. Two working processes, which are the static friction process and the sliding friction process, are clearly reflected by the monotonic test results. The cyclic test results indicate that the SEDC specimens demonstrate satisfactory plastic development with full hysteretic curves, stable load capacity, reliable deformation ability, and favorable energy dissipation ability. The U-shaped bending plates exhibited a track-like deformation pattern without any observed tears or cracks. The NAO friction pads demonstrated a fragmented damage pattern, while the Brass friction pads demonstrated a linear scratch damage pattern. SEDC specimens equipped with Brass friction pads exhibited better low-cycle fatigue performance, which can be attributed to the favorable wear resistance of the Brass material. In addition, finite models of SEDCs are established and validated based on Abaqus. The combined working mechanism of SEDC, including the contribution ratio of load capacity and dissipated energy from the bending part and the friction part, is clearly revealed. Furthermore, the influence of parameters including the thickness (t), width (B), straight section length (l), radius (R), and height (h) of the bending part, as well as the pre-tightening force (pc) and the friction coefficient (f) of the friction part, are also summarized based on both the experimental and numerical analyses. Further discussions, including the calculation of the seismic behavior factor and the measurements for accurate construction, are conducted.

Design, simulation, and experimental investigation on a novel multi-drive pattern three-degree-of-freedom rotary piezoelectric motor

Three-degree-of-freedom (3-DOF) rotary piezoelectric motors often suffer from low positioning accuracy, complex excitation signals, and uneven preloading, limiting their application in precision drive systems. To address these issues, this study proposes a novel multi-drive pattern 3-DOF rotary piezoelectric motor, comprising a sandwich-type hollow cylindrical stator, a spherical rotor, and a pre-tightening structure. The proposed motor can operate in both inertial and traveling wave drive patterns. In the inertial drive pattern, the first-order and the third-order bending vibration modes of the stator are simultaneously excited by a sawtooth wave signal, generating a saw-tooth displacement on its driving feet to rotate the rotor around the x or y-axis. In the traveling wave drive pattern, two mutually orthogonal first-order bending vibration modes of the stator are simultaneously stimulated by two sinusoidal signals, generating a traveling wave on its driving feet to rotate the rotor around the z-axis. Initially, finite element analysis is used to simulate the operating principle of the stator and determine its geometric dimensions. Subsequently, a prototype of the sandwich-type hollow cylindrical stator is fabricated, and its vibration characteristics are tested to confirm the validation of the proposed operating principle and the correctness of the finite element simulation. Finally, a prototype of the proposed 3-DOF rotary piezoelectric motor is assembled, and its mechanical output characteristics are experimentally evaluated. Experimental results indicate that when the excitation voltage is 200 Vpp, the no-load rotary velocities of the motor prototype in three rotation directions are 79 r min−1, 76 r min−1, and 101 r min−1, respectively, start/stop response times are 10 ms/8.6 ms, 13.4 ms/6.2 ms, and 15.5 ms/7.7 ms, respectively, and the angular displacement resolutions are 7.4 μrad, 8 μrad, and 11.4 μrad, respectively. The proposed motor exhibits high mechanical integration, 3-DOF rotation, few excitation signals, adjustable pre-tightening force, and high positioning accuracy advantages, holding the potential applications in fields such as robotic technology and space pointing mechanisms.

Numerical investigation on the failure mode of the upper shear hinge in steel spring floating slab track

Fracture on hinge bars and fixed bolts of upper shear hinges is a common problem in prefabricated steel spring floating slab tracks (SSFST), adversely affecting train operation safety and comfort. To investigate the potential failure modes, this paper established a four-slab SSFST model to analyze the force condition of upper shear hinges. Force transmission between floating slabs as well as the stress level of the hinge bars and fixed bolts under the most unfavorable vehicle cases were respectively simulated by the structural mechanics method (SMM) and the FEA software ABAQUS. Stress influence lines of hinge bars and fixed bolts under the moving vehicle load resulting from ABAQUS were extracted to evaluate the fatigue behavior based on the fatigue S-N curve by the post-processing software FE-SAFE. Furthermore, the influence of different pre-tightening force on fixed bolts’ fatigue behavior was discussed. The results of the two simulation methods match well, suggesting that force between floating slabs is mainly transmitted by rails, while shear hinges only account for about 1/3 of the bending moment and 1/5 of the shearing force. Hinge bars and fixed bolts are both sufficient in strength, yet fatigue problem is likely to happen to the latter. The fatigue failure mode and location of fixed bolts are related to the value of pre-tightening force. Large stress range or high stress mean always exists as the pre-tightening force varies, meaning that bolt fatigue is an intrinsic failure mode of the upper shear hinge in SSFST.

ВЕРТИКАЛЬНЫЕ ТИТАНОВЫЕ ВИНТЫ С МОДИФИЦИРОВАННЫМ ПОКРЫТИЕМ ДЛЯ ПОВЫШЕНИЯ НАДЁЖНОСТИ ФИКСАЦИИ И СТАБИЛИЗАЦИИ АБАТМЕНТОВ К ПЛАТФОРМЕ ДЕНТАЛЬНЫХ ИМПЛАНТАТОВ

Vertical screws of abutments after dental implantation tend to loosen, unscrew and break, which is associated with low strength, tribological and corrosion properties of screw material under stress and aggressive environment in the oral cavity. The main causes of problems with dental screws are a decrease in their fatigue strength due to defects, residual tensile stresses and hydrogen pickup of surface layer, as well as the process of fretting corrosion that occurs under conditions of micro-displacement under cyclic loads of conditionally stationary tribocoupling. The design and operational characteristics of abutment screws, the main problematic properties of titanium materials are considered, the calculated dependences of torque, pre-tightening force, friction coefficients in thread and on support surface are given. The analysis of numerical values of these parameters is given. It is concluded that the use of vertical titanium screws with functional coatings is one of the ways of improving the reliability of the dental implantation system. The results of studies of the BioPateks diamond-like coating of the a-C:H/a-SiC-Ag system for vertical titanium abutment screws applied using cold atmospheric plasma are presented. The effectiveness of this coating has been demonstrated in metallographic analysis, static tensile tests, tribological studies, tests under microabrasive wear conditions, studies of barrier properties from the release of toxic vanadium and aluminum ions, studies of surface defects during fretting fatigue. The BioPateks coating and its application technology can be used both in industrial and in clinical and laboratory conditions. For these purposes, small-sized and low-energy equipment is used.

Application of SLAM in bolt tightening monitoring process based on intelligent data algorithm analysis

Abstract In this paper, firstly, according to the requirements of static monitoring of bolt tightening quality, the bolt tightening process can be divided into four stages: snug, elastic deformation, yielding and plastic deformation, and the SLAM technology is applied to bolt monitoring modeling and building engineering modeling. Next, the pre-tightening force for the bolt is measured using the waveform expansion method, and the bolt tightening index can be determined. Then, all the collected bolt data are randomly combined into two categories of loosening and tightening to form a training data set, and the improved intelligent data algorithm is used to train and predict them. The results show a linear correlation between tightening degree x |τ ɛ| and preload force change ΔF under 0.31kN and 0.22kN loading gradients, and the linear correlation coefficient of the fitted curve is greater than 0.9215. The results of the data analysis verify the correctness of the theoretical analysis.