In hydraulics, threaded plugs are used to close various manufacturing holes and other fluid channels. They are preloaded to ensure sufficient sealing force. Since the range of recommended thread and underhead friction coefficients for preloaded threa...
The calculation of manual tightening torque applied by clinicians plays a critical role in achieving optimal preload for dental implants. However, there is a research gap when it comes to understanding the specific calculus involved in this process....
The disc cutter is a key rock-breaking component of tunnel boring machines, and during operation, improper assembly preload often leads to uneven wear of the cutter. To study the effect of preload force on the friction torque of paired tapered roller...
This study aimed to evaluate the effect of two coating materials, a silicone sealing gel and a polytetrafluoroethylene (PTFE) tape, on the screw preload and removal torque value (RTV) to develop strategies to prevent prosthetic screw loosening. We ex...
Background: To compare the loss of preload in absence of loading and after a fixed number of cyclic loadings on 7-mm distal cantilever in two different connection systems using all-on-four prosthetic model. Methods: Two equal models of an edentulous...
The stability and integrity of the abutment-implant connection, by means of a screw, is fallible from the moment the prosthetic elements are joined and is dependent on the applied preload, wear of the components and function. One of the main causes o...
High-strength bolts are widely used in structural connections, and the preload affects the failure behavior of bolts. In this paper, a variable cross-section bolt (VCSB) with weakened strength to induce fracture is designed. Quasi-static tensile expe...
Background: Abutment screw loosening (ASL) is the most frequent mechanical complication in dentistry, leading to prosthetic instability and biological risks. Preload, generated during screw tightening, is critical for maintaining stability but is inf...
Aiming at analyzing the load characteristics and friction torque of triple-row hub bearings for new energy vehicles, this work established a comprehensive theoretical and experimental methodology for predicting the internal load distribution and fric...
23 November 2020
Introduction: Different implant–abutment connections have been developed to reduce mechanical and biological failure. The most frequent complications are loss of preload, screw loosening, abutment or implant fracture, deformations at the differ...
Oral rehabilitation with dental implants has resulted in high success rates. However, some complications have been described, such as the loss of the prosthetic screw. Some manufacturers sell screws with different coatings to avoid screw loosening, b...
The aim of this study was to evaluate the stability of prosthetic screws after applying cyclic loadings in an “all-on-four” rehabilitation model with the OT Bridge system. The model was tested both with and without anterior screws. Four i...
Torque and velocity fluctuations in internal combustion engines (ICEs), particularly during idle and low-speed operation, can reduce efficiency, increase vibration, and impose mechanical stress on coupled systems. This work presents the design, simul...
The tightening torque applied to a screw in a provisional restoration immediately after implant placement in a fresh extraction socket is often too low to gain sufficient preload force. Therefore, abutment screw loosening is a common complication. Th...
In this paper, a dynamic simulation analysis model was established for CMGB (control moment gyroscope bearing) under the conditions of time-varying moment. The influences of the moment’s response time, axial preload, and working temperature on...
The preload has a significant impact on the output performance of ultrasonic motors. To achieve optimal output from the ultrasonic motor, this paper proposes a novel multi-objective optimization method for preload, utilizing the Non-dominated Sorting...
Preload optimization is very important for ultrasonic motors’ design and application. In this paper, a novel method for a traveling-wave rotary ultrasonic motor is proposed. Firstly, based on linear regression and the analytic hierarchy process (AHP)...
In this study, a novel shape memory alloy actuated bearing active preload system (SMA-BAPS) was proposed and experimentally demonstrated. SMA actuators placed in a single or antagonistic configuration were employed to drive the screw pair and thus fu...
The tightening torque values considered in the assembly of vehicle subparts are of great importance in terms of connection safety. The torque value to be selected is different for each bolted joint type with respect to mechanical features. While the...
Multi-degree-of-freedom piezoelectric motors have the advantages of high torque and resolution, simple structure, and direct drive, which are widely used in robot wrist joints, deep-sea mechanisms, medical equipment, and space mechanisms. To solve th...
The present paper describes the structural analysis performed on a preloaded bolted joint. The first joint modeled was comprised of a conventional cylindrical flange that was sliced to simplify the analysis for two bolts in lieu of four. This involve...
The purpose of this study is to numerically analyze a 3D model of an implant under fatigue loads. A bone and a V shape implant were modeled using SolidWorks2008 software. In order to obtain an exact model, the bone was assumed as a linear orthotropic...
A high-gear-ratio anti-backlash 3K planetary gearbox with a preloaded flexure-based carrier is a suitable reducer for robot joints owning to its compact design and high transmission accuracy. However, to design such a 3K planetary gearbox with high b...
Achieving accurate fit in implant-supported prostheses is critical for avoiding mechanical complications; however, the influence of digital manufacturing techniques and abutment designs on misfit and preload remains unclear. This study evaluated the...
Aim: This study aimed to compare the torque loss, fracture load, compressive strength, and failure types of selective-laser-sintered cobalt chromium (SLM-Co-Cr), computer-aided design and computer-aided manufacturing zirconium oxide (CAD-CAM-ZrO), an...
Dielectric elastomer actuators (DEAs) are increasingly recognized for their potential in robotic applications due to their ability to undergo significant deformation when subjected to an electric field. However, they are often limited by their low ou...
Based on the research and development demand of the 400 km/h high-speed turnout, a new type of elastic iron tie plate based on stiffness optimization is proposed. The new elastic iron tie plate is expected to reduce the stiffness unevenness and effec...
Self-loosening of the prosthetic screws is a major mechanical problem affecting roughly 10% of dental implants, according to the literature. This phenomenon may lead to micro-movements that produce crestal bone loss, peri-implantitis, or structural f...
We recently proposed a numerical model using equivalent circuit models to analyze the resonance characteristics of Langevin transducers and design them in a systematic manner. However, no pre-load torque biased by a metal bolt was considered in the m...
Bolts have the advantages of simple installation and easy removal. They are widely applied in aerospace and high-speed railway traffic. However, the loosening of bolts under mixed loads can lead to nonlinear decreases in pre-loading. This affects the...
Preloaded bolted connections are one of the most used approaches for anchoring steel structures and equipment. Preload is induced by a mechanical tightening of the nut with the required torque. In the case of anchor bolts embedded in a concrete base,...
We report here on a laser ultrasonic system to indirectly evaluate the preload force of different-frequency piezoelectric bolts. This newly developed system enables us to achieve the goal of non-contact excitation and synchronously collects the laser...
The working principle and motion process of an aviation wet clutch are analyzed. The initial velocity before the friction pair engaged is solved. The transient Reynolds equation is modified, and an oil film bearing capacity model and a micro-convex b...
Fretting fatigue is a well-known and dangerous damage mode that occurs on the mating surfaces of mechanical components, mainly promoted by a combination of stress distribution, contact pressure distribution, and relative sliding (micro)motion between...
This in vitro experiment aimed to understand the difference in preload acting on an abutment screw under different angles of angulated screw-retained crown and the performance after cyclic loading. In total, thirty implants with angulated screw chann...
Background: This study aimed to evaluate the influence of a screw coating on the screw preload and removal torque value (RTV) with and without the application of a cyclic load (CL) to make screws with greater untightening resistance to prevent screw...
High-strength bolts play an essential role in connecting steel structural components across bridges, buildings, and machinery, thanks to their low cost and broad adaptability. However, prolonged exposure to complex loading and harsh environments can...
The sealing performance of ultra-high-pressure solenoid valves faces significant challenges, particularly under low-temperature conditions. Due to the difference in thermal expansion coefficients between the valve seat and the sealing tube, combined...
Background: Screw loosening is considered a leading mechanical complication in implant-supported restorations. Hybrid abutments, combining a titanium base with a ceramic mesostructured, were proposed to enhance stability and esthetics. Objective: We...
Pipeline transportation of oil and gas is widespread. To improve inspection and maintenance, a pipeline inspection robot was developed in our study. We employed a threaded nut mechanism with a preload spring and diameter-adjustment methods. A torque...
Background/Objectives: Screw loosening and vertebral fractures remain common after vertebral body tethering (VBT). Because tightening torque sets screw preload, its biomechanical effect warrants explicit modeling. In this paper, a Finite Element (FE)...
Although bolted joints may appear simple and are easy to manipulate, they are challenging to model and analyze due to their complex structural patterns and statically indeterminate nature. Ensuring the structural integrity of these joints requires ma...
Gas foil thrust bearings (GFTBs) have been successfully used to support the axial load of oil-free microturbomachinery with low drag friction due to the low viscosity of gas or air used as a bearing lubricant. However, the widespread use of GFTBs in...
Bolted connections are the main method of connecting the components of an aero-engine low pressure rotor. Due to the influence of the elastic interaction relationship, it is easy to cause uneven distribution of the preload force of the bolt group, al...
The present paper describes a study conducted at the request of the operator of machining center equipment. The operator observed undesirable indicators in terms of increased backlash and vibration of the milling head and poor quality of the machined...
The use of composite materials has shown steady growth in recent years due to their excellent specific mechanical properties and the possibility to reduce the weight of vehicles without impairing their safety and comfort. Continuous fibre-reinforced...
The aim of this study was to examine the settling of abutments into implants and the removal torque value under static loading. Five different implant-abutment connections were selected (Ext: external butt joint + two-piece abutment; Int-H2: internal...
This study investigates the impact of tightening torque (preload) and the friction coefficient on stress generation and fatigue resistance of a Ti-6Al-4V abutment screw with an internal hexagonal connection under dynamic multi-axial masticatory loads...
Rather than using longitudinal “muscle” as in biological inchworm, the existing magnetic active elastomer (MAE)-based inchworm robots utilize magnetic torque to pull and push the soft body, which hinders its locomotion mobility. In this p...
Bolted joints are highly loaded components and serious issues may arise from improper fastening and in particular from too high or too low preload. Friction at the underhead plays an important role, as it significantly affects the achievable preload...
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