Tightening Torque Value Research Articles

OPTIMIZING THE PRODUCTION OF LAYERED SYSTEMS INCORPORATING MFC TRANSDUCERS AND MODELING BOLT JOINT LOOSENING DETECTION WITH THEIR APPLICATION

This article offers a concise overview of cutting-edge techniques for monitoring bolt joint looseness and optimizing Macro Fiber Composite (MFC) based structure manufacturing for structural health monitoring emphasizing MFC-host structure attachment methods, optimal MFC placement, and the impact of adhesive layers between MFC and the host structure. The study also employs Ansys software to conduct Multiphysics modelling and characterization of bolt joint conditions using MFC piezoelectric transducers. Emphasizing joint looseness under varying pretension loads, the results demonstrate that increasing preload, up to the full tightening torque value (14.5 Nm), increases the natural frequency, indicating enhanced joint stiffness. Conversely, looser connections result in lower natural frequencies, signifying decreased joint stiffness. The article focuses on assessing the effectiveness of Macro-Fiber Composite (MFC) for monitoring the health of bolt joints, providing a simple and efficient method for modelling the structural response of MFC-integrated bolt joints, facilitating convenient and rapid engineering analysis and testing.

Prediction of Self-Loosening Mechanism and Behavior of Bolted Joints on Automotive Chassis Using Artificial Intelligence

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 tightening torque value is an important indicator, the bolt preloading value is always a more reliable parameter in terms of whether a secure tightening can be achieved or not. For this reason, when it is desired to create reliable joints, the preloading value that the tightening torque input will create on the connection package should be calculated well. This study presents an integrated approach using Taguchi method (TM) and neural network (NN) to predict the self-loosening mechanism of bolted joints in automotive chassis engine suspension connections. External loading acting on the joints of the engine suspension was collected from bench tests. NN was applied to establish the relationship between controlled factors and loosening rate. The results showed that the proposed approach can be used to predict mechanism of self-loosening and behavior of bolted joints without additional tests, and it is possible to make predictions with very low error rates using artificial intelligence techniques.

Bolt pre-load CAE analysis and validation: FEA simulation of hex bolt tightening torque for IDU assembly of 2-wheeler in MSC Nastran and practical validation

In any machine or automotive product, different nuts, bolts and other types of fasteners are used during assembly of the different parts. It is required to properly define the fastening loads or torques during the fastening application. In certain product assembly being manufactured and assembled by Varroc Engineering ltd, it is required to find out the exact tightening torque of the bolt as it could crack the product if the torque applied beyond certain limit. The product is IDU. In this we have done the bolt preload analysis in MSC FEA (Patran) software. Firstly, we found the allowable clamping force by analytical method. Then we performed bolt pre-load analysis to find the stress and displacement values which could be induced due to the certain tightening torque. Then we tested the part for same into lab and validated the results. Due to this simulation, we have been able to understand the behavior of the part under different bolt tightening torque values and thus it has enabled the designer to finalize the tightening torque values. Same concept of simulation is being applied now for tightening torque problems of different application.

Robust tool wear monitoring system development by sensors and feature fusion

AbstractThis study introduces a tool wear monitoring system that uses multiple sensors and a feature fusion technique. To improve the robustness of the system, different tightening torque and spindle speed conditions were considered in the experimental design stage. Vibration signals in three coordinates and sound signals were collected and transformed by fast Fourier transform for feature extraction. Two types of features in the frequency domain were used to establish the proposed system, including the mean value features selected by the class mean scatter feature selection criterion and statistical features by Gradient Class Activation Mapping++ (Grad‐CAM++). The proposed monitoring system was established using a hierarchical neural network structure and feature fusion of the sensors. Cross‐validation was introduced to demonstrate the performance and effectiveness of our approach under various tightening torque values and spindle speeds.

Peri-implant bone alterations under the influence of abutment screw preload stress. A preclinical vivo study.

The study purpose was to examine peri-implant bone alternations around osseointegrated implants caused solely by abutment screw preload stress using different tightening torque values. Twenty 20- to 22-week-old Japanese white rabbits received two implants each in right and left femurs. Implants were randomly assigned to one of three tightening torque groups or the control (Cont) group. After 8weeks, 35Ncm torque was delivered to abutment screws in the recommended torque (RT) group (n=16). Other screws received 70Ncm torque as the high torque (HT) group (n=16). Temporary tightening (TT) groups (n=8) received only 70Ncm torque without preload stress as screws were untightened immediately. Cont group (n=40) remained in situ. Animals were euthanized at 4, 6, 8, and 10weeks after torque application. Micro-CT images were then taken, and undecalcified ground sections were stained with toluidine blue. Cross-sections of cortical bone showed remodeling activities adjacent to the implant in all groups. While bone marrow spaces appearance was relatively small in Cont and TT groups, RT and HT groups showed large bone marrow spaces and extensive remodeling activity. Bone-to-implant contact was significantly less in RT and HT groups compared with Cont and TT groups at different time points (p˂.05). Furthermore, RT and HT groups showed significantly less bone volume and area (p˂.05). Results suggested that preload stress without any occlusal loading might negatively affect peri-implant bone stability and initiate bone remodeling. This could alter bone mechanical properties, subsequently influencing long-term implant success.

Dynamic Characteristics of Plastic Plates With Bolted Joints

AbstractThis paper discusses the dynamic characteristics of plastic plates with bolted joints. The effects of tightening torque on the modal properties of the plates are investigated. Experimental and numerical modal analyses have been conducted on the plates made of acrylonitrile butadiene styrene (ABS), that are clamped by bolted joints. First, the effect of tightening torque on the vibration mode of the plates is investigated by experimental modal analyses. Modal testing has been conducted for various tightening torque values, and the relationships between the modal parameters and the tightening torques are discussed. Second, the effects of tightening torque on the vibration mode are studied by using analytical models for the bolted joints based on the finite element method (FEM). Based on the comparisons between the experimental and the numerical results, a modeling strategy for the boundary conditions between the plates is introduced and its validity is discussed. From both experimental and numerical studies, it is shown that the natural frequencies of the structures with bolted joints tend to converge to specific values as tightening torque increases. Moreover, it is also shown that when modeling the bolted plates by FEM, the inter-plate motion should be constrained by a boundary condition to properly suppress the out-of-phase motion of the plates.

Prediction of failure stages for double lap joints using finite element analysis and artificial neural networks

Abstract Prediction of failure stages of double lap bolted joints is an important task for design. Finite element (FE) and artificial neural networks (ANNs) methods are widely used in such tasks to reduce time, money, and efforts consumed in laboratory experiments. Three dimension elastic-plastic FE analysis was adopted to simulate the failure stages of double lap joint in the present work. After completing mesh sensitivity analysis for the present FE model, only nine experiments were conducted to verify the prediction of the present FE model. Taguchi technique was applied to reduce the number of loading cases (different joint geometry and tightening torque) from one hundred twenty five cases of loadings to only twenty seven cases of loadings. The FE results of twenty seven cases of loadings were accomplished to provide the training set of ANNs. Finally, a comparison between the results obtained from FE and ANNs was made. Results indicated that, either FE or ANNs can highly predict the failure stages of double lap bolted joints for different e/D, w/D, and tightening torque values. Therefore, FE and ANNs methods may be considered good candidates to predict the mechanical behavior and failure mode of such joint.

The failure stages of bolted double-lap metallic joints: experimental study

In this study, the effect of clamping force on the bolted double-lap joints has been investigated experimentally. The mechanical behavior of the present joint has been divided into several stages based on the sequence of failure. The commencement failure occurred in such joint is the sticking failure, i.e., loose of clamping effect. One of the main objectives of present investigation is to study the effect of tightening torque value (T = 0–30 Nm) on the sticking failure load, i.e., initiation of the relative sliding. Three different geometries (e/D = 1, 2, and 3) have been adopted to get different modes of failure, namely bearing, shear, and tensile. A steel sheet AISI 1006 with fixed width 30 mm and thickness 3 mm was used. The present experimental results showed six different stages identifying the mechanical behavior of the double-lap joint namely; sticking failure, bearing failure, shearing failure, ultimate strength, tensile/shear crack initiation (depending on the value of e/D), and lastly final failure. For e/D = 2 and 3, the maximum value of sticking failure load is obtained at T = 25 Nm, while T = 30 Nm for e/D = 1. Furthermore, for all values of e/D, the values of sticking failure load are approximately the same at T = 30 Nm. In the case of small values of tightening torque (T < 25 Nm), the stiffness of the joint before sticking failure increased by increasing the value of e/D and T. The difference between the stiffness of joints with different values of e/D, e/D = 1–3, decreased by increasing the tightening torque.

Fastener Spacing &amp; Tightening Torque of Gasket Joints of Oil Filled Transformers

Objectives: Design of leak-proof gasket joint of the transformer is very important to ensure the safe long-term service of a transformer. This paper gives the properties of gaskets, fastener spacing calculation and recommended tightening torque values. Methods/Statistical Analysis: This study commences with a review of the equations applicable for the calculation of leak rate of gas and oil through a gasket joint. Findings: A comparison of properties of various types of gaskets used is carried out and NITRILE Rubber and NITRILE Cork gaskets are selected as the most suitable ones for transformer application. The procedure to calculate the fastener spacing and the recommended tightening torque values are given. Application/Improvements: This paper is useful for the transformer designer because the gasket types and parameters fastener spacing calculation and torque requirements are not consolidated in any published paper. Further studies to determine the relationship of surface finish, gasket characteristics, fastener spacing and tightening torque on the long-term performance of the transformer. Keywords: Distribution Transformers, Gasket, Tightening Torque, Fastener Spacing, Oil-Filled Transformers

Finite Element Analysis of Screw-Tightening Torque Applied to Custom and Conventional Abutment

The aim of this study was to design an abutment with an esthetic emergence profile contour using CAD technology and compare the stress distribution within the structure between the custom abutment and conventional abutment according to the screw tightening torque using 3D finite element analysis (FEA). The maximum tensile principal stress was found in the endpoint of the screw head and the start point of the screw line with regard to the application of the tightening torque of the screw. A similar pattern was observed in all of the following screws: 10N·cm, 20N·cm, and 30N·cm. The tightening torque of the screw had a significant impact on the changes in the stress of the abutment and screw fixture. This study also found that the condition in which the screw load was applied showed a more realistic description of the behavior of a single fixed dental implant than the condition in which the screw load was not applied. This study examined the optimal tightening torque value of the screw for the denture used in this study at a location slightly higher than 20N·cm. The difference in the custom abutment and conventional abutment did not have a significant impact on the supporting bone with regard to the external load. In regard to the stress occurring in the screw, the custom abutment had a lower degree of stress than the conventional type. Therefore, a screw fracture would occur less frequently in a custom abutment than a conventional abutment.

Role of Washers in Controlling Loosening of Full Threaded Bolted Joints

Bolted joints are used for fastening components together in the industry, aeronautics and in railways. These joints may get loose with time and if not attended timely may result in catastrophic failure also. The purpose of this study was to examine the effect of tightening torque on loosening. For this purpose tests were conducted using three different tightening torque values, in the vicinity of rated torque. Washers of different types are used in bolted joint, with an understanding that they prevent or retard loosening. This study also attempts to examine the role of two types of most commonly used washers: the plain washer and the spring washer. Trials were also performed on joint without any washer, for the sake of comparison of loosening performance of the joint. The results of this experimental study are shown in terms of starting point of loosening of joint and rate of loosening of the joint. Various combinations of washers for three values of tightening torque are considered in the experimental study. The results are useful in understanding the role of type of washer in prevention of loosening of the bolted joint.

On failure mode analysis in a bolted single lap joint under tension-shearing

This paper investigates the failure mode of a bolted single lap joint formed from thin sheet of aluminum alloy 6082 T6 with several configurations of assemblies. Two types of geometric characteristics, i.e. the width and the distance between the hole center and the free edge of the substrate, are used in order to verify the effect of the distance between the bolted joint and the edge effects. Mechanical testing in tensile shearing are carried out to verify the influence of: tightening torque, number and disposition of bolted joint (1 bolted joint, 2 bolted joints (vertical and horizontal row), 3 bolted joints and 4 bolted joints). The tightening torque value isn’t significant for the failure mode and has little influence on the global behavior of the bolted joint. The failure modes depend on the edge effects, on the number and disposition of bolts.

Bacterial Colonization of the Implant–Abutment Interface Using an In Vitro Dynamic Loading Model

Previously, we demonstrated that the geometry of the fixture-abutment interface influences the risk of bacterial invasion into the internal part of the implant, although the contribution of loading on this invasion was not evaluated. The aim of the present study is to use an in vitro dynamic-loading model to assess the potential risk for invasion of oral microorganisms into the fixture-abutment interface microgap of dental implants with different fixture-abutment connection characteristics. Twenty-eight implants were divided into two groups (n = 14 per group) based on their microgap dynamics. Group 1 was comprised of fixtures with internal Morse-taper connection that connected to standard abutments. Group 2 was comprised of implants with a four-groove conical internal connection that connected to multibase abutments. The specimens were immersed in a bacterial solution of Escherichia coli and loaded with 500,000 cycles of 15 N in a wear simulator. After disconnection of fixtures and abutments, microbial samples were taken from the threaded portion of the abutment, plated, and cultured under appropriate conditions. The difference between loosening and tightening torque value was also measured. One of the 14 samples in Group 1 and 12 of the 14 of samples in Group 2 developed multiple colony forming units for E. coli. Implants in Group 1 exhibited an increase in torque value in contrast to implants in Group 2, which exhibited a decrease. This study indicates that differences in implant design may affect the potential risk for invasion of oral microorganisms into the fixture-abutment interface microgap under dynamic-loading conditions.

STUDY ON STRUCTURAL BEHAVIOR OF FRICTION TYPE HIGH STRENGTH BOLTED JOINTS HAVING GAP IN THE CONTACT PLANE

High strength bolted friction type joints may have gap in the contact plane because of permissible deviation of steel plate thickness. In the “Part 1” of last paper, we proposed analytical method to evaluate the slip load of such joints tightened by turn-of-nut method. The validity of the proposed analytical method was verified, because the calculated slip load by the analytical value of the contact force was in good agreement with the experimental results. We consider popular three methods which may prevent from the reduction in slip load of gapped joint. One is the way increase the preliminary tightening torque value, the other is increase the nut rotation of tightening, further, the effect of the bolt location are discussed based on the analytical method which is described in the last paper.

STUDY ON STRUCTURAL BEHAVIOR OF FRICTION TYPE HIGH STRENGTH BOLTED JOINTS HAVING GAP IN THE CONTACT PLANE

High strength bolted friction type joints may have gap in the contact plane because of permissible deviation of steel plate thickness. In the “Part 1” of last paper, we proposed analytical method to evaluate the slip load of such joints tightened by turn-of-nut method. The validity of the proposed analytical method was verified, because the calculated slip load by the analytical value of the contact force was in good agreement with the experimental results. We consider popular three methods which may prevent from the reduction in slip load of gapped joint. One is the way increase the preliminary tightening torque value, the other is increase the nut rotation of tightening, further, the effect of the bolt location are discussed based on the analytical method which is described in the last paper.