Browse Topic: Fastening

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Design and Control of a Target Plate Fastener Assembly and Disassembly Actuator for Divertor Maintenance in Fusion Reactors2026-99-01827/31/2026
With the development of controlled nuclear fusion technology, the tokamak device, as the most promising magnetic confinement fusion reactor for advanced engineering applications, requires remote maintenance of its internal components, which has become a key factor affecting both operational efficiency and safety. As a critical component directly exposed to high-temperature plasma, the divertor target plate needs to be periodically replaced and carefully maintained to ensure stable and reliable reactor operation. However, this region is subject to extreme conditions, including high temperature, high vacuum, and intense radiation, making conventional manual maintenance infeasible. This necessitates the development of intelligent and automated teleoperation systems. To address the automated assembly and disassembly requirements of divertor target plates, this study designs an integrated target plate actuator comprising key functional units: a positioning module, a screwing module, a quick-change module, and a passive compliance structure. The actuator achieves rapid and precise alignment with target plate holes, accommodates bolts of different specifications, and exhibits excellent impact resistance. Furthermore, stiffness and mechanical analyses, supported by finite element simulations, verify the actuator’s safety and reliability under high loads and impact forces. To further enhance operational performance, a segmented disassembly and assembly control strategy based on reinforcement learning is proposed, enabling the actuator to adaptively handle torque variations and ensure precise and stable bolt operations. The results demonstrate that the proposed actuator and control strategy significantly improve the accuracy, stability, and efficiency of target plate operations under complex working conditions, providing a reliable solution for automated divertor maintenance in tokamak devices.
Zang, Xizhe, Yu, Xingzu, Cao, Zhangbin
A Comparative Study of Pin Connection Methods in Aircraft Structural Assemblies2026-99-05697/10/2026
In the aerospace industry, pins are crucial for fastening multiple connected structural parts, ensuring a flush connection that does not protrude from the assembly’s surface. These pins are installed through various methods to meet stringent mechanical and anti-loosening requirements, essential for aircraft structural integrity. Typical pin installation techniques include clearance fit with punch point installation, small interference fit with punch point installation, large interference fit with punch point installation, and interference fit without punch point installation. This study examines the connection reliability and manufacturability of different pin assembly processes, focusing on load testing under operational conditions. Results indicate that a small interference fit (0-0.01mm) combined with punch point installation provides high connection reliability and ease of manufacture, with punch point methods notably enhancing loadbearing capability and assembly integrity. In contrast, larger interference fits (0.01–0.04mm) require complex manufacturing steps, such as liquid nitrogen cooling for cold shrinkage, and the use of a shaft press for assembly, which increases difficulty and risks damaging both pins and surrounding structural parts. This research provides insights into optimizing pin assembly techniques to improve the durability and performance of aircraft structural assemblies.
Hua, Shengyan
Mitigating Cracking in COP Optics through Annealing and Step-Torquing2026-26-07646/1/2026
Polymeric optical materials such as Cyclo Olefin Polymer (COP) are adopted in aerospace lighting systems due to their excellent optical clarity, dimensional stability, moldability and weight saving advantages over glass. However, their relatively low toughness and the presence of residual molding stress make them prone to crack initiation during mechanical fastening. During its installation, crack formation was consistently observed around self-tapping screw interfaces, raising concerns over reliability, maintainability, and compliance with durability requirements. A structured Design of Experiments (DOE) was performed to identify root causes and evaluate potential mitigation methods. The investigation revealed that residual stresses in the COP material, combined with localized stress concentrations during screw tightening, were the primary drivers of crack initiation. Two complementary process improvements were identified and validated as part of mitigation plan: (i) annealing of the optics prior to assembly to relieve internal stress, and (ii) using step-torquing method to fasten the screws, to gradually distribute applied loads and reduce localized stress peaks. Post-assembly observation over three days confirmed a significant reduction in crack initiation. The combined annealing and step-torquing approach demonstrated a substantial reduction in crack generation probability, providing a practical and repeatable process for enhancing the robustness of polymeric optic assemblies. This work contributes a generalizable methodology for mitigating assembly-induced failures in advanced polymer materials and supports broader adoption of lightweight, high-performance optics in aerospace applications.
S, Nikhil, Singh, Abhimanyu Kumar, Katageri, Praveen, SP, Pradeep, Chandra, Praveen
EP40: Structural Epoxy Used for Steel Bonding in Marine Applications26AERP04_074/1/2026
Master Bond EP40 is a two-part, room temperature curing epoxy for bonding, sealing, coating, and encapsulating. EP40 bonds well to a variety of substrates, including naval steel, the primary structural metal used in the shipbuilding industry. Master Bond Inc., Hackensack, NJ To reduce its environmental impact and pollution, the shipping industry is investigating methods to construct more lightweight ships. One potential method is using adhesive bonding techniques to replace traditional welding and riveted joints on ships to fabricate lighter ships with smaller carbon footprints. However, adhesives age and deteriorate when exposed to moisture, high temperatures, and ultraviolet light. This makes it necessary to understand how they age in maritime environments to determine whether they can truly replace traditional welding techniques. To this end, researchers at Centro de Investigación en Tecnologías Navales e Industriales (CITENI) and Centro de Investigación TIC (CITIC) developed a new method for studying adhesive aging on naval steel substrates. Master Bond EP40 was selected as the test adhesive for this method due to its strong performance and suitability for marine conditions. By using EP40, the team ensured that the observed adhesive bonding behavior would reflect a high-quality epoxy's potential in ship structures. The goal was to evaluate how EP40 bonds to naval steel and how the bulk epoxy material would behave in seawater to provide insights into the construction of lighter ships using this approach.
On the Modal Characteristics of Motor Stators under Different Interlaminate Fastening Conditions14-15-01-00052/14/2026
The increasing demand for quiet and efficient electric vehicles has highlighted the importance of understanding vibration and noise characteristics of motor stators. Previous studies have extensively modeled electromagnetic excitation and laminated structures, but there has been little experimental evidence clarifying how different interlaminate fastening methods affect vibration modes under comparable conditions. This knowledge gap limits the ability to optimize fastening strategies for noise and vibration control in practical motor design. In this study, laminated stator cores were fabricated with different fastening conditions—bolting, clinching, and welding—and subjected to vibration testing and experimental modal analysis. Natural frequencies, damping ratios, and mode shapes were identified for torsional, circumferential, and breathing modes. The results revealed that the in-plane torsional natural frequencies increase with bolt axial force, while clinching provides additional resistance to interlaminate movement but shows only a minor dependence on the number of clinching points. In contrast, the circumferential modes and the breathing-type (0,0) mode remain largely unaffected by these fastening variations. Welding points did not exhibit a consistent trend across the tested conditions, indicating that their influence on the modal properties is less systematic compared with bolting and clinching. The findings contribute not only to fundamental understanding of laminated stack vibration behavior but also to practical guidelines for designing fastening strategies that enhance vibration robustness and acoustic performance in automotive electric motors.
Matsubara, Masami, Saito, Akira, Shimada, Shogo, Oishi, Taizan, Furuya, Kohei, Kawamura, Shozo, Tajiri, Daiki
AI-Driven Predictive Methodology for Bolt Integrity in Vehicle Durability Testing2026-26-06481/16/2026
The application of AI/ML techniques to predict truck endgate bolt loosening represents a major innovation for the automotive industry, aligning with the principles of Industry 4.0. Traditional physical testing methods are both expensive and time-consuming, often identifying issues late in the development process and necessitating costly design changes and prototype builds. By harnessing AI/ML, manufacturers can now analyze endgate slam and bolt preload data to accurately forecast potential bolt loosening issues. This predictive capability not only enhances quality and safety standards but also significantly reduces the costs associated with tooling and builds. The AI/ML tool described in this paper can simulate a variety of load conditions and predict bolt loosening with over 90% accuracy, considering factors such as changes in loads, bolt diameters, washer sizes, and unexpected masses added to the endgate. It provides valuable design insights, such as recommending optimal bolt diameters and the use of high-friction washers to ensure strong and reliable connections. By enabling continuous monitoring and real-time adjustments, this tool helps maintain the integrity of bolted joints under diverse operational conditions. This methodology reduces dependence on physical testing along with considerable cost avoidance and accelerates the vehicle development process. It offers a more efficient and cost-effective approach to vehicle development. Through the integration of these advanced technologies, the automotive industry can fully embrace the concepts of Industry 4.0, leading to smarter manufacturing processes and improved product reliability.
Sivakrishna, Masani, Das, Mahat, Singh, Abhinav, Karra, Manasa, Shienh, Gurpreet, Luebke, Amy
Novel Methodology for Assessment of Bolted Joints Under Vibration Fatigue2025-28-028711/6/2025
The smart industrial revolution in any organization brings faster product delivery to the market, which can meet customer expectations and full life requirements without failure. Failure per machine (FPM) is a very critical metric for any organization considering warranty cost and customer perception. One such area which needs a detailed evaluation is bolted joints. Bolts play a pivotal role when integrating a subassembly with the main structure. Often, it is challenging to address bolt failure issues due to vibration induced in structures. Current bolt virtual evaluation methods help to evaluate bolts in simple loading conditions such as axial and bending loads. But it is quite complicated to evaluate the bolts which are prone to vibration loading. Traditional methods of using gravity loads miss out on dynamic characteristics, hence it must be simulated using modal dynamic analysis. With the current vADV (virtual accelerated design verification) method it is not possible to capture correct physics as modal analysis converts all frictional contacts to bonded contact resulting in change of load path. Different methodologies to evaluate bolts under vibration fatigue. Contact optimization of a bolted joint using contact pressure and load path study Acceleration extraction using modal dynamic analysis and load super-position. Both the methods have shown good correlation with field data and have been utilized in ongoing product development programs to address ADV (Accelerated Design Verification) failures. Pros and cons of these methods are understood and documented in this study.
Desale, Amit Nanaji, Singh, Gurwinder, Vhatkar, Rushikesh, Patil, Akhil
Evaluating the Influence of Material Properties and Hardness on Tightening Torque2025-28-025511/6/2025
Earthmoving machines are equipped with a variety of ground-engaging tools that are joined by bolted connections to improve serviceability. These tools are made from heat-treated materials to enhance their wear resistance. Attachments on earthmoving machines, including buckets, blades, rippers, augers, and grapples, are specifically designed for tasks such as digging, grading, lifting, and breaking. These attachments feature ground-engaging tools (GET), such as cutting bits or teeth, to protect the shovel and other earthmoving implements from wear. Torquing hardened plates of bolted joint components is essential to ensure uniform load distribution and prevent premature failure. Therefore, selecting the proper torque is an important parameter. This study focuses on analyzing various parameters that impact the final torque on the hardened surface, which will help to understand the torque required for specific joints. Several other parameters considered in this study include hardware material, coefficient of friction, end bit and cutting-edge material, and their hardness. Understanding the influence of surface hardness on bolted joint torque is crucial for optimizing performance, reliability, and longevity of bolted connections in various engineering applications
Parameswaran, Sankaran Potti, Bhosale, Dhanaji, Kumar, Rajeev
Strength Prediction of Self-Piercing Riveted Joints Using Practical Regression and Bayesian Neural Network2025-01-506810/10/2025
Self-piercing riveting (SPR) is a key joining method in multi/thin-material automotive structures, yet accurately predicting the mechanical strength of SPR joints remains challenging due to numerous influencing factors. Empirical engineering equations [1] provide a foundation for estimating lap-shear and cross-tension strength but require several geometric parameters that are often unavailable in the design phase. To address this limitation, we extract and leverage the core physical relationships embedded in these formulas. By reformulating the dependence of joint strength on the yield strength and total thickness of the sheet stack as practical regression models, we enable strength prediction using only commonly available material properties. Furthermore, a Bayesian convolutional neural network (BCNN) model is developed to incorporate additional material features, offering improved prediction accuracy and uncertainty quantification.
Soproni, Istvan, Womack, Darren, Liu, Zongyue, Balaji, Ashwin, Kulange, Deepak
Titles, SAE Subcommittee G-3E Aerospace Tubing Installation Documents, Selection OfARP1987/3A (Current)6/17/2025
The scope of this SAE Aerospace Recommended Practice (ARP) is to establish the procedure for creating titles of aerospace tubing and clamp installation documents generated by SAE Subcommittee G-3E.
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Semi-Automatic Riveter G39 Replacement2025-01-01605/2/2025
This paper reports on a new design of semi-automatic riveting machine designed to be affordable. This work started in 2024. There are no customers yet. The machine is all electric. The machine installs interference bolts as well as squeeze rivets. Cost is a key criterion. The machine must feed a wide variety of fasteners. This machine is called Flexriveter.
Zieve, Peter, Reznicek, Jeffrey
Optimization Methodology Development of FEA and Design Analysis on High Voltage Bolted Joints for Electric Vehicles2025-01-82444/1/2025
To promote the electric performance and safety of development for EV mobility, optimization methodology and design guide of high voltage bolted joint should be newly developed. This paper describes the development process of multi-physics (electrical, mechanical, thermal) FEA methodology, various experimental tests and establishment of optimization methodology of busbar bolted joint design in terms of bolt preload validation and joint temperature rise. The various key factors on high voltage joint tightening are quantitatively studied by utilizing this optimized methodology.
Lee, Joon Ha, Wu, Zhijun, Gerini-Romagnoli, Marco, Nassar, Sayed
Self-Piercing Riveting (SPR) of Magnesium High Pressure Die Casting and Dissimilar Materials2025-01-82314/1/2025
Solid state joining processes are attractive for magnesium alloys as they can offer robust joints without the porosity issue typically associated with welding of magnesium and dissimilar materials. Among these techniques, Self-Piercing Riveting (SPR) is a clean, fast and cost-effective method widely employed in automotive industry for aluminum alloys. While SPR has been proven effective for joining aluminum and steel, it has yet to be successfully adapted for magnesium alloy castings. The primary challenge in developing magnesium SPR technology is the cracking of the magnesium button, which occurs due to magnesium's low formability at room temperature. Researchers and engineers approached this issue with several techniques, such as pre-heating, applying rotation to rivets, using a sacrificial layer and padded SPR. However, all these methods involve the employment of new equipment or introduction of extra processing steps. The aim of this work is to develop a SPR technique which adapts current SPR machines with minimal changes to existing processes to create crack-free joint between magnesium and dissimilar materials. In the current study, feasibility of joining coupons of typical structural materials including high strength steel, aluminum alloys and composite to magnesium high pressure die casting (HPDC) was investigated. It was demonstrated that a joint is achieved which is crack-free both internally and externally. Also, the lap shear strength of the joints was investigated. Given its flexibility in material selection and compatibility with existing SPR process lines, this method holds significant potential to facilitate more applications on materials with limited ductility.
Tabatabaei, Yousef, Wang, Gerry, Weiler, Jonathan
Experimental Determination of the Residual Torque Range in a Plastic Connector of the Fuel Pump Module at End of Life2024-36-012912/20/2024
The study of residual torque is necessary in various fields to ensure the safety and reliability of bolted joints. The present study aims to determine, experimentally, the decrease in torque applied to a nut used in the assembly of two polymeric components (POM - Polyoxymethylene). These components are part of the fuel supply module, responsible for supplying fuel from the tank to the engine. This reduction in torque initially applied is mapped to the end-of-life of the components and is used as an approval criteria in the audit procedures of the Robert Bosch company. The first component features an overmolded metallic screw, injected into POM. The mating part is also injection molded from POM and is assembled onto the first part, secured by tightening a metal nut. Due to the plastic-to-metal interface, it’s expected that there will be a reduction in the initially applied torque required to fasten the pieces together. The study was based on 5 steps: 1 Theoretical study on residual torque at the plastic-to-metal interface; 2 Verification of plastic component deformation due to applied torque; 3 Assembly of samples for practical tests; 4 Mapping of torque decrease in samples by time. In this case, a digital torque wrench was used; 5 Analysis of the data and determination of the residual torque range at the end of the product’s life. After the study was completed, it was determined a minimum residual torque, for the end of the product’s life, in this application. This criterion enables more accurate control in field part verification, improves product quality, and optimizes failures identification.
Spitaletti, Laís Scotelari, da Fonseca, Márcio Ghiraldelli
A Virtual Calibration Strategy and Its Validation for Large-Scale Models of Multi-Sheet Self-Piercing Rivet Connections05-17-03-00164/29/2024
This article presents a strategy for the virtual calibration of a large-scale model representing a self-piercing rivet (SPR) connection. The connection is formed between a stack of three AA6016-T4 aluminum sheets and one SPR. The calibration process involves material characterization, a detailed riveting process simulation, virtual joint unit tests, and the final large-scale model calibration. The virtual tests were simulated by detailed solid element FE models of the joint unit. These detailed models were validated using experimental tests, namely peeling, single-lap joint, and cross-tests. The virtual parameter calibration was compared to the experimental calibration and finally applied to component test simulations. The article contains both experiments and numerical models to characterize the mechanical behavior of the SPR connection under large deformation and failure.
André, Victor, Costas, Miguel, Langseth, Magnus, Morin, David
Electric Motor Noise Reduction with Stator Mounted NVH Insert Ring2024-01-22054/9/2024
Electric motor noise mitigation is a challenge in electric vehicles (EVs) due to the lack of engine masking noise. The design of the electric motor mounting configuration to the motor housing has significant impacts on the radiated noise of the drive unit. The stator can be bolted or interference-fit with the housing. A bolted stator creates motor whine and vibration excited by the motor torque ripple at certain torsional resonance frequencies. A stator with interference fit configuration stiffens the motor housing and pushes resonances to a higher frequency range, where masking noise levels are higher at faster vehicle speeds. However, this comes with additional cost and manufacturing process and may impact motor efficiency due to high stress on stators. In this paper, a thin sheet metal NVH ring is developed as a tunable stiffness device between the stator and the motor housing. It is pre-compressed and provides additional torsional rigidity to mitigate torsional excitations. A CAE model is developed to model, analyze, and optimize the NVH ring for the bolted stator configuration. A system-level simulation method is utilized to characterize the interactions of the stator, the NVH ring, and the motor housing as well as the retention force variation of the insert ring due to thermal aspects. The optimized NVH ring provides increased torsional stiffness comparable to an interference fit configuration, which leads to reduced motor noise in the critical low frequency range.
He, Song, Tran, Xuan, Naismith, Gregory, Du, Isaac, Patruni, Pavan Kumar, Baladhandapani, Dhanasekar
Material Modelling of Lamination Stack in Electric Machines2024-01-27454/9/2024
The rotor and stator of electric motors consist of multiple materials, of which steel forms the majority of mass and volume. Steel in electric motors is commonly in the form of thin sheets (laminations), stacked along the axis of the rotor. The structural integrity of such a stack can be ensured using bolting, welding or bonding of the laminations. Predictive mechanical finite element simulations of these laminated stacks can become computationally intense because the steel sheets are thin, and the motor often contains hundreds of them. If the laminations are modelled individually, the size of the elements is very small compared to the overall dimensions and the interface between the laminations need to be modelled as well. In this paper, we present an alternate method of modelling this laminated stack as a single solid body using homogeneous and orthotropic material property, instead of representing each lamination. This provides realistic predictions of mechanical performance, while keeping the computational time significantly lower than modelling separate steel sheets. Modal testing and associated simulations are presented at the stator stack level as well as assembly level where the detailed stator is fitted into a housing.
Goel, Ashish, P, Praveen, Sharma, Hiren, Faggioli, Thiago
Design Optimization and Methodology for Safe Wheel End Joint2024-01-26524/9/2024
Threaded joints are considered the most basic of components. Although in use for over a century, significant problems still exist with their usage. Wheel bolt loosening in overloaded segments such as HD tippers and high-speed intercity buses poses a safety challenge for drivers, passengers, and pedestrians. Wheel nut loosening is a notable cause of service, fretting, and cracks in the mating components; contributing a significant chunk of warranty cost to the company. The need of the hour is to reinforce these joints while keeping resources at bay. This paper establishes a methodology for the evaluation and design of a safe wheel bolt joint interface including key parameters such as embedding, axial forces, and shear forces. It is necessary to obtain the minimum preload requirement for a wheel bolt joint to hold the clamped surfaces intact, which if not maintained otherwise would cause relative movement, play, shear load onto the bolt, and eventually failure. For physically auditing the pre-load the “on-off-on tightness checking method” has been incorporated. The study shows a significant increase in pre-load in geomate-coated nuts (M22X2.5 10.9 grade nuts binding rim, drum, and hub having PCD 335 mm) via optimizing the fastener finish and internal profile. A risk assessment study has been done involving bolt-nut grades, bearing stress, and thread stripping. Proof of concept has been established, verified for feasibility, and implemented in HD tippers. This approach saves any cost impact, development time, or changes in service operations, all being crucial to the industry. This proves to be a frugal and efficient way of strengthening bolted joints without disturbing size, PCD, or grade while maintaining modularity across platforms.
Raghatate, Shreyas, Sharma, Suchit, Sindal, Vinayak
Resistance Rivet and Insert Welding - A Flexible Manufacturing Technique for the Aluminum/FRPs-Steel Multi-Material Body Structures2024-01-20714/9/2024
Automotive body structures are being increasingly made in multi-material system consisting of steel, aluminum (Al) and fiber-reinforced plastics (FRP). Therefore, many joining techniques such as self-piercing riveting (SPR) and adhesive bonding have been developed. On the other hand, OEMs want to minimize the number of joining techniques to reduce the manufacturing complexity. Amount all joining methods, resistance spot welding (RSW) is the most advanced and cost-effective one for body-in-white. However, RSW cannot be applied for joining dissimilar materials. Therefore, a novel Rivet Resistance Spot Welding method (RRSW) was developed in which Al or FRP components can be directly welded to steel structures with existing welding systems. RRSW uses rivet-like double T-shaped steel elements as a welding adapter which are formed or integrated into Al or FRP components during their forming process. After that, they are welded to the steel components by RSW. This paper shows at first the development results on Steel – Al RRSW. An appropriate rivet geometry was developed using FEM simulation and made mechanically. The corresponding welding parameters were determined experimentally. Tests on different specimens and components were conducted. The static and fatigue strengths of RRSW are mostly better or equal to that of SPR. The corrosion resistance is superior to SPR. Finally, a section of a car roof made of Al sheet was stamped and welded with the steel structures in neighborhood using RRSW proofing the technology. In next step, RRSW was extended for long fiber reinforced thermoplastics components manufactured by compression molding. A 2nd rivet was successfully developed using FEM welding simulation with the target of minimal temperature in FRPs to avoid their thermal damage, and wide welding process window. The entire process was proved on an FRP seat cross member welded in steel floor panel. The strength of this RRSW is also equal or better than SPR.
Fang, Xiangfan, Zhang, Fan, Xu, Hongli
Simulation of Self-Piercing Riveting Process in Aluminum Alloy 5754 Using Smoothed Particle Galerkin Method2024-01-20694/9/2024
Self-piercing riveting (SPR) are one of most important joining approaches in lightweight vehicle design for Body-in-white (BIW) manufacturing. Numerical simulation of the riveting process could significantly boost design efficiency by reducing trial-and-error experiments. The traditional Finite Element Method (FEM) with element erosion is hard to capture the large plastic deformation and complex failure behaviors in the SPR process. The smoothed Particle Galerkin Method (SPG) is a genuine meshless method based on Galerkin's weak form, which uses a novel bond-based failure mechanism to keep the conservation of mass and momentum during the material failure process. This study utilizes a combined FEM and SPG approach to join Aluminum sheet 5754 using a full three-dimensional (3D) model in LS-DYNA/explicit. To mimic the rivet insertion process, the mesh-free SPG method is used to model the material part of the upper and lower sheet where the rivet pierces through, while FEM methods for computational efficiency model the remaining parts. Sensitivity studies are conducted to investigate the impacts of critical model parameters and accurate material properties. This work illustrates that precise material properties and 3D CAE modeling can provide fundamental and insightful information for the SPR process.
Zou, Jie, Huang, Li, Ren, Bo, Zhang, Jingyi, JI, Yuxiang, Guobi, Tan, Zhan, Zhenfei
Analysis of Loads Applied to Wheels of Heavy Vehicles and Study on Loosening of Hub Bolts and Nuts2024-01-22514/9/2024
Heavy vehicles such as construction machinery generally require a large traction force. For this reason, axle components are equipped with a final reduction gear to provide a structure that can generate a large traction force. Basic analysis of vertical load, horizontal load (traction force), centrifugal force, and torsional torque applied to the wheels of heavy vehicles such as construction machinery and industrial vehicles, as well as actual working load analysis during actual operations, were conducted and compiled into a load analysis diagram. The loosening tendency of wheel bolts and nuts that fasten the wheel under actual working load was measured, and the loosening analysis method was presented. The causes of wheel fall-off accidents in heavy trucks, which have recently become a problem, were examined. Wheel bolts are generally tightened by the calibrated wrench method using a torque wrench. The method is susceptible to variations in friction coefficient and tightening torque, and human error affects the tightening torque. Even if the tightening torque (initial clamping force) is insufficient, effective loosening prevention is considered necessary to prevent serious accidents such as wheels falling off. In forklifts, the number of hub bolts is limited due to space limitations, so hub nuts have a spherical or conical alignment structure that allows each nut and bolt to absorb the drive torque and slippage of the bearing surface. In wheel loaders, for example, there is space to install hub bolts, and the clamping force of the bolt sustained slippage of the bearing surface to prevent loosening and fatigue”
Hareyama, Soichi, Manabe, Ken-ichi, Kobayashi, Satoshi
Prevention of Operational Errors in Semi-Automatic Riveters by Machine Vision Systems Using Deep Learning2024-01-19443/5/2024
This paper reports the development of an operation support system for production equipment using image processing with deep learning. Semi-automatic riveters are used to attach small parts to skin panels, and they involve manual positioning followed by automated drilling and fastening. The operator watches a monitor showing the processing area, and two types of failure may arise because of human error. First, the operator should locate the correct position on the skin panel by looking at markers painted thereon but may mistakenly cause the equipment to drill at an incorrect position. Second, the operator should prevent the equipment from fastening if they see chips around a hole after drilling but may overlook the chips; chips remaining around a drilled hole may cause the fastener to be inserted into the hole and fastened at an angle, which can result in the whole panel having to be scrapped. To prevent these operational errors that increase production costs by requiring repair work, we have developed an operation support system that processes the monitor images so that the operator can distinguish markers before drilling and detect chips before fastening. Initially, we developed rule-based image processing, but it could not achieve sufficient accuracy because of the complexity of defining rules related to images features. Therefore, we turned instead to image processing based on deep learning, and after efforts to achieve the required accuracy and processing speed, the developed system now outperforms the rule-based system and we have improved the production efficiency of this riveter. Deep learning technology can be used to improve the productivity of a wide range of production equipment, both existing and new.
Yamanouchi, Shiho, Aoki, Naofumi, Nagano, Yoya, Moritake, Daichi, Sakata, Tatsuhiko, Kato, Kunihito
Electroimpact Automatic Fan Cowl Riveter2024-01-19223/5/2024
The Electroimpact Automatic Fan Cowl Riveter exhibits new and unique design features and automated process capabilities that address and overcome three primary technical challenges. The first challenge is satisfying the customer-driven requirement to access the entire fastening area of the fan cowl doors. This necessitates a unique machine design which is capable of fitting ‘inside’ a fan cowl door radius. The second challenge is determining drill geometry and drill process parameters which can produce consistent and high-quality countersunk holes in varying mixed-metal stack-up combinations consisting of aluminum, titanium, and stainless steel. The third challenge is providing the capability of fully automatic wet installation of hollow-ended titanium rivets. This requires an IML-side countersinking operation, depositing sealant throughout the OML and IML countersinks and the hole, automatically feeding and inserting a rivet which is only 5mm long and 6mm in head diameter and flaring the rivet tail to a ‘sub-flush’ condition.
Merluzzi, James, Schultz, Rich, Ernsdorff, Bryan, Peterman, Randy, Luker, Zachary, Stansbury, Erin, Murakonda, Sai Krishna
Optimizing the Design Parameters and Nanoclay Content of Thin GLARE Laminate Riveted Joints under Pull-Through Test Using Grey Relational Analysis2023-01-508612/13/2023
The study investigates the optimization of design parameters of riveted joints such as diameter of rivet, edge distance, and the amount of nanoclay filler in the modified GLARE laminate single lap riveted joints under pull-through test. Taguchi’s L9 orthogonal array was used to plan the experiments. The failure mechanism of riveted joints was observed to be elongation of rivet hole, followed by stress concentration, crack initiation, propagation in the interface, coalition of multiple cracks leading to delamination in the laminate. The failure of joint finally occurred by rivet pin fracture. The regression equations were developed for both failure load and maximum displacements with prominent level of confidence and the reliability of the equations were confirmed by experiments. The effect of individual and interaction of factors was evaluated using analysis of variance (ANOVA). The grey relational analysis (GRA) was conducted to determine the optimum combination of factors and levels. The GRA predicted the combination of factors and levels as “A3 (Diameter of rivet – 6.4 mm) -B3 (Edge distance – 35 mm) -C3 (Nanoclay wt.% - 5).”
Sabarilal Krishnan, K., Hariharasakthisudhan, P., Logesh, K., Kannan, Sathish
Building Engines for War: Air-Cooled Radial Aircraft Engine Production in Britain and America in World War IIR-56411/13/2023
Dive into the heart of wartime innovation and manufacturing through this groundbreaking book, unveiling a riveting narrative of technological mastery and organizational ingenuity. This meticulously researched work challenges conventional views of wartime production, offering a fresh perspective on the incredible efforts that drove the Allies to victory. Young's insightful analyses illuminate the strategic collaboration between the aerospace and automotive industries, showcasing their collective adaptation that created the engines powering victory. Spanning continents, Young examines the transformation of aircraft engine manufacturing during World War II. Unearthing the operations of key players such as the Bristol Aeroplane Company, Pratt & Whitney, and Wright Aeronautical, he sheds light on the monumental shift from traditional batch production to revolutionary quantity production. Readers will witness the birth of new factories, the development of advanced machine tools, and the innovation required to produce engines of unparalleled complexity and precision. Through Young's fresh perspective, the book unveils the intricate interplay of crisis techno-politics, engineering resilience, and the pivotal role of innovation in shaping the tides of history. This book is not just a study of the past; it is a critical foundation for understanding the dynamics of wartime production that continue to influence our world today. "Edward Young's reconstruction and analysis of the Allies' massive World War II aircraft engine programs is priceless, unique, thorough and critical - all at once." Philip Scranton Professor Emeritus, History of Industry and Technology, Rutgers University "Having spent decades as a financial-industry analyst, and with his interests in aerospace history, Young was the right person to tackle this subject. His charts are superb, and he analyses resource utilization on both sides of the Atlantic. In the end, thanks to his impressive research and analytical capabilities, a reader should understand how one part of the huge and complex materiel problem facing the Allies was met and overcome. Anyone interested in the 'back-home' story of how we won the war should read this excellent volume. It is not light reading, but it is worth every bit of time spent reading it." Col Scott A. Willey USAF (Ret), Book Review Editor, and former National Air and Space Museum docent
Young, Edward M.
Gripper to Defend Bolts in Magnetic Track Brake System2023-01-187211/5/2023
Carbide-tipped gripper dowel secures the bolted joints and plays a significant role in the safety and reliability of the magnetic track brake system. With mainline trains speeds over 250 km/hr the magnetic track brake is automatically activated in case of the emergency brake. As the train passes over switches, crossings, and narrow curves with track distortion, it creates an exceptional lateral and longitudinal force on the bolted joints. The introduction of a gripper between several bolts reduces the shear force of the bolt to a large extent. This solution has the added benefit of facilitating maintenance. The paper presents the application of the gripper in the magnetic track brake and the validation of the gripper using analytical and experimental tests. This study may be applied to a wide range of bolted joints. The experimental results demonstrate the ability of gripper and maximize the durability of the bolt to prevent bolt joint failures. The results indicate a higher shear force on the gripper. The study shows that the bolt safety factor has improved by 2.7 times in the magnetic track brake system.
K, Manjunath, Mishra, Nirmalya, Kumar, Sandeep, Montua, Sebastian
SAE TOMORROW TODAY: Buckle Up! We're Talking Future Trends134037/17/2023
From AI and ChatGPT to geopolitics and global supply chains, a multitude of trends are converging and paving the way for a historic transformation that will reverberate across industries and sectors. Are you ready? For a rousing conversation that is as wide-ranging as it is thought-provoking, we sat down with Katrin Zimmermann, CEO and Managing Director of TLGG USA, to discuss the trends impacting mobility, technology, globalization, and much more. Fasten your seatbelts for an honest discussion that is certain to push boundaries and open minds.
Hineman, Marcie
Wheel Mounting Elements for Off-Highway Disc WheelsJ714_202306 (Current)6/5/2023
This SAE Recommended Practice includes wheel mounting elements subject to standardization in a series of industrial and agricultural disc wheels. The disc may be reversible or nonreversible and concave or convex. (See Figure 1 and Table 1.)
MTC8, Tire and Rim
Research on Crack Detection Method of Self-Piercing Riveting2023-01-08634/11/2023
Compared with traditional welding, self-piercing riveting technology has unique advantages and is widely used in automobile lightweight technology. The riveting quality of self-piercing riveting is closely related to the safety and durability of automobiles. The detection of riveting quality has gradually become an important part of the automobile manufacturing process. The generation of surface cracks under self-piercing riveting will affect the riveting strength, which in turn affects the riveting quality. Therefore, the detection of riveting external quality is transformed into the detection of riveting surface cracks. The existing artificial vision-based riveting lower surface crack recognition technology is inefficient, subjective and cannot be applied on a large scale. Therefore, this paper will propose a local-overall strategy based on image processing and computer vision. Firstly, three sub-image crack recognition networks based on extreme learning machine and feature extraction are constructed. Considering that the crack recognition network based on feature extraction has a large room for improvement in accuracy and the limitation of feature description operator on image expression, two sub-image crack recognition networks based on convolutional neural network are constructed. Then based on the traversal search algorithm, four representative full-size images are used to show the detection effect of different crack recognition models. The final results show that the crack recognition network based on convolutional neural network has the best detection effect.
Wang, Kun, Zhan, Zhenfei, Xu, Hailan
Low Friction Coating for High Temperature Bolted Joints in IC Engines2023-01-07334/11/2023
The IC engine still plays an important role in global markets, although electrified vehicles are highly demanded in some markets. Emission requirements for stoichiometric operation are challenging. This requires the bolted joints for turbo, EGR (Exhaust Gas Recirculation) and exhaust manifold to work under much higher temperature than before. How to avoid fastener breakage due to bolt bending caused by cyclic changes of the thermal conditions in engines is a big challenge. The temperatures of the components in the exhaust, EGR (Exhaust Gas Recirculation) and turbo systems change from ambient temperature to about 800 ~ 1000 °C when engines run at peak power with wide-open throttle. The temperature change induces catastrophic cyclic bending and axial strain to the fasteners. This research describes a method to reduce the cyclic bending displacement in the fasteners using a low friction washer. Mathematical modeling and FEA methods have been employed to specify the design space based on the engine operating conditions. A series of tribological bench tests were conducted to evaluate different coatings on the washer under room temperature and up to 600 °C. A sensitivity study has also been done to identify the factors that affect the coefficient of friction (CoF). A multi-layer coating has been found to be able to provide a low coefficient of friction under high temperature and high pressure. It meets the design requirements and has been validated by engine dyno tests on the exhaust system.
Zhang, Wensheng, Wang, Bingxu, Barber, Gary, Lamonaca, Gianni
Material and Bonding Conditions Optimization of Monocoque Inserts Based on Formula Student Electric China2023-01-08084/11/2023
In the Formula Student Electric China (FSEC), the body structure is generally divided into two types, truss steel tube body and carbon fiber load-bearing body (monocoque). The monocoque is loved by Formula Student teams around the world because it has a higher stiffness and lighter weight than the truss steel tube body. With the widespread application of monocoque, it also brings more problems. Due to the use of the monocoque, the connection between each component and the body was changed from the welding of the original truss steel pipe frame to a bolted connection. However, the bolted connection will provide a large preload force to the monocoque, resulting in the monocoque easily crushed in the local, so it is necessary to pre-bury an enhanced part in the monocoque to ensure the connection strength, that is, the embedded part. At present, aluminum plug-ins after topological hollow processing are being used. Although the weight is reduced a lot, the assembly cross-sectional area is reduced, resulting in the inserts are easy to loosen, the connection is unstable, and even the lifting ears may be loose under severe working conditions, so that the vehicle is in an extremely unsafe state. It is necessary to optimize the material and bonding conditions of the inserts. In this paper, two engineering plastics, PPS and PPS with 30% glass fiber (PPS30), were selected and the bonding conditions were optimized in terms of several variables. The results show that the bonding strength is improved by the use of PPS30 and the optimization of the bonding conditions.
Kang, Yuxin, Guo, Wei, Wu, Shukai
Crack Detection and Section Quality Optimization of Self-Piercing Riveting2023-01-09384/11/2023
The use of lightweight materials is one of the important means to reduce the quality of the vehicle, which involves the connection of dissimilar materials, such as the combination of lightweight materials and traditional steel materials. The riveting quality of self-piercing riveting (SPR) technology will directly affect the safety and durability of automobiles. Therefore, in the initial joint development process, the quality of self-piercing riveting should be inspected and classified to meet safety standards. Based on this, this paper divides the self-piercing riveting quality into riveting appearance quality and riveting section quality. Aiming at the appearance quality of riveting, the generation of cracks on the lower surface of riveting will seriously affect the riveting strength. The existing method of identifying cracks on the lower surface of riveting based on artificial vision has strong subjectivity, low efficiency and cannot be applied on a large scale. Therefore, based on image processing and computer vision, this paper proposes an automatic identification method of surface cracks under self-piercing riveting based on convolutional neural network (CNN) and local-global strategy. Aiming at the quality of riveting section, the riveting process and section quality are analyzed by numerical simulation, and a multi-objective optimization method is proposed to assist in improving the quality of riveting section.
Wang, Kun, Zhan, Zhenfei, Xu, Hailan, Hu, Ke, Chen, Xiatong
Relationship between Material Strength and Friction Coefficients for Aluminum Alloy Bolt2023-01-09414/11/2023
Multi-material structures are demanded to reduce weight of vehicles. We have to reduce the weight of not only structural material but also joining elements to achieve multi-material structures. Some aluminum alloy bolts have begun to be used in the automotive fields recently. In our previous study, we investigated the tightening characteristics of Aluminum alloy A5056 bolt. The results showed that friction coefficients of thread surfaces and bearing surfaces are obviously different in comparison with those of steel bolt. The tightening strength, especially the proof clamp force, is very important to determine the target clamp force of bolted joint. However the proof clamp force of bolt is different from the proof tensile strength of bolt because the proof clamp force significantly depends on the friction coefficient of thread surfaces. Therefore we can easily know the proof clamp force for each bolt material if we can estimate the friction coefficients from the tensile strength. In this study, we have investigated a relationship between the tensile strengths of aluminum alloy bolts and these friction coefficient of contacting thread surfaces to easily estimate the proof clamp force of bolt using the tensile strengths. We have revealed the relationships of four different aluminum alloy bolts, A5056, A6056, A6061 and A2024. The results showed that there is a certain correlation between the friction coefficients of thread surfaces and tensile strengths for each bolt material if the bolted joints were lubricated by machine oil ISO VG46. However the correlation between the friction coefficient and the tensile strength was not high if the bolted joints were not lubricated.
Hashimura, Shinji, Horinouchi, Kenta, Kmibeppu, Kazuki
A Comprehensive Methodology to Design and Develop Suspension System Bolted Joints using Vehicle Test Loads and CAE Simulation2023-01-06084/11/2023
The bolted joints in suspension systems are subjected to severe external service loads during vehicle operation. To prevent the loaded joint from loosening and allowing it to retain its potential energy stored during assembly, a holistic design approach is needed. This paper explains the methodology to design and optimize bolted joints for the suspension systems of a modern 7-seater sports utility vehicle. The optimization technique consists of - 1 Extensive benchmarking of global benchmark vehicles with similar suspension architecture and gross vehicle weights to derive preliminary torque and joint preloads. 2 Measuring external loads acting in x, y and z directions using a wheel force transducer on various durability tracks. 3 Performing Multi body dynamic simulations to obtain the loads at various bolted joint locations. 4 Taking the input of the external loads acting on the individual joints and perform a simulation to evaluate slip at joinery for a given preload. 5 Bolt characterization measurements to establish the torque to be applied to achieve the required preload at the joint. Based on the results, joinery design approaches are discussed which focus on increasing the resistance against slip and utilizing the optimum preload applied during assembly. For critical joints experiencing high service loads, the torque to yield (torque plus angle) method is prescribed instead of the elastic tightening method along with reduction of the axial gap. For double shear joints having steel sleeve and sheet metal interface, improvements seen with the addition of serrations/knurling on the contact surface of the sleeve are discussed. The stiffness of mating parts is increased for proper bolt load transfer. With the incorporation of these design modifications in the joinery, extensive vehicle durability tests are performed in the vehicle, and no incidences of joinery loosening/slipping are observed. The efficacy of the design improvement was reflected in the residual torque values which showed no reduction after the test compared to the start of the test.
Vellandi, Vikraman, Namani, Prasad, Nair, Sharad, Nayak, Bhargav A., Chaudhari, Varun, Patnala, Avinash, Senthil Raja, T., Arunachalam, M
Optimization of the Bolted T-Joint of an Electric Bus Body Frame Considering the Fatigue Performance2023-01-00284/11/2023
This work focuses on the robust optimization of the bolted T-joint part of the steel-aluminum body frame of an electric bus, aiming to improve the performance of fatigue durability of the local structure of the bolted T-joint part. First, finite element model is built for the bolted T-joint part connecting the chassis and the side of the body frame for fatigue durability analysis. Surrogate model for design optimization is fitted by the Kriging method based on the finite element (FE) analysis data. Then, a multi-objective optimization problem is formulated to enhance the fatigue life of the element with the worst fatigue durability performance, and to decrease the deformation of the element with the largest deformation, by choosing the thickness of the beams of the T-joint part as the design variables. A deterministic multi-objective optimization problem is performed by the adaptive simulated annealing (ASA) method. To further improve the reliability of the optimization result, a six-sigma level robust design optimization is carried out based on the Monte Carlo sampling method and the archive-based Micro Genetic Algorithm (AMGA) method. The minimum fatigue times of the optimized bolted T-joint increased by 60.80% compared with that before optimization. The results show that the maximum deformation of the optimized vehicle is reduced by 4.87% and the minimum fatigue times are increased by 25.1% in the common working conditions. The proposed optimization method can effectively improve the comprehensive performance of the bus body frame.
Gan, Jinlin, Zou, Li, Yang, Xiujian, Liu, Jiaqi
A High-Performance Milling Machine for Aerospace Applications2023-01-10023/7/2023
As the aerospace industry moves toward determinate assembly and ever-tighter manufacturing tolerances, there is a need for automated, high-precision milling, trimming and drilling equipment that is specialized for aerospace applications. Precision countersinking is a common requirement for aircraft parts, but this is not a process that typical general-purpose milling machines are able to accommodate without the use of specialty tools such as depth-stop tool holders. To meet this need, Electroimpact has designed a 5-axis milling machine with high-speed clamping capability for countersink depth control. A custom trunnion and head with a quill and an additional clamp axis provide clamping functionality similar in speed and precision to a riveting machine, while maintaining the accuracy and features of a conventional machining center. An additional focus on design for pre-compensation accuracy has allowed the system to achieve post-compensation path and positioning tolerances that are competitive with premium milling machines. This combination of capabilities makes the system well suited for a variety of cutting and drilling processes for aircraft manufacture. This paper will describe the background and design process that led to the development of this system, and will provide details on its capabilities, specifications, and possible applications.
Bigoney, Burt, Smith, Scott, Bruns, Michael
On-Line Pose Measurement and Adjustment of End Effector Based on Laser Tracker for Robotic Drilling System2023-01-09823/7/2023
Automatic robotic drilling is a widely used way of fastening in the field of aircraft assembly and is worth studying continuously. Drilling accuracy is one of the most remarkable properties of the system, which is directly related to the absolute positioning accuracy of the robot end effector. Due to the kinematic errors and gravity of the robotic system itself, the nominal pose and the actual pose of the end effector are no longer consistent with each other. It is necessary to keep the high positioning accuracy of the system. In this paper, an automatic robotic drilling system with high positioning accuracy is proposed. Generally, there are two methods to improve positioning accuracy: off-line calibration and on-line adjustment. An off-line calibration based on the DH method is proposed to identify and modify the parameter errors of the robot. A 6- degree of freedom industrial robot is integrated into the drilling system. After the kinematic error modeling of the robot is established, the sample points in the reachable workspace of the robot are measured, the kinematic errors are identified and compensated, and the calibration process is achieved. Then an on-line pose measurement and adjustment of the end effector based on a laser tracker are developed. Transforming relations between coordinate systems of all parts of the drilling system are firstly obtained accurately. With the robotic drilling end-effector as the working module and the laser tracker as the measuring module, A closed-loop control system for positioning accuracy is established. By measuring the actual pose of the end-effector and comparing it with the nominal pose, the pose of the end-effector is adjusted in real-time. The experiment results indicate that after pose measurement and adjustment the positioning accuracy of the end effector meets the accuracy requirements.
Tang, Yue, Zheng, Jinhui, Zhang, Mao
Evolution of Mobile Robotic Manufacturing Systems at Spirit AeroSystems2023-01-09963/7/2023
Efforts toward the mechanization of aircraft manufacturing began as a divided focus between devices like power tools that augment human worker capability and purpose-designed, “monument” automation. While both have benefits and limitations, the capability of modern industrial robots has grown to the point of being able to effectively fill the capability gap between them, offering a third option in the mechanization toolbox. Moreover, increasing computer processing power continues to enable more advanced approaches to perception to inform task planning and execution. Higher performance robots supplemented with greater ability to adapt to various conditions and scenarios have also led to the ability to operate reliably and safely outside traditional fixed-installation, caged work cells. This in turn has made it feasible for robot systems to work in ever more complex environments and applications, including the world of aircraft assembly with its numerous challenges like workpiece scale, precision issues due to compounding tolerance stack-ups, and confined and often crowded spaces – including the potential for interaction with human workers. Mobile industrial robot systems are becoming more common throughout the aerospace industry and the most popular use case is still drilling and fastening. Spirit AeroSystems has been at the forefront of this trend since the early 2000’s in terms of system architecture and configuration, technology testing and maturation, and deployment into production use cases. In conjunction with a number of supplier partners, Spirit has nearly 20 years’ worth of history and lessons learned regarding drilling and fastening processes performed by mobile industrial robotic systems including several new systems across multiple programs and aerostructure configurations.
Richardson, Curtis A., Davis, Chris R.
Spring Clips and Cushion Selection for Metal Tube Support, MetricMA1806A (Current)10/13/2022
Spring clips (inner and outer) and associated PTFE single split cushion designed to support metric metal tubes (or inch tubes, using the inch series cushion).
G-3, Aerospace Couplings, Fittings, Hose, Tubing Assemblies
Effect of Initial Assembly Gaps on Thread Strip and Fatigue Assessment of Bolted Joint2022-28-009010/5/2022
Bolted joint is a popular method for assembly of mechanical systems which are typically designed by considering members to be in full contact without initial gap. However, manufacturing imperfections or part tolerances can introduce gaps between members. This initial gap is proven to have an adverse effect on the performance of bolted connection. The gap introduces additional bending moments (B.M.) during tightening operation and affects the loads shared by the threads thereby aggravating thread strip and fatigue performance. The aim of this paper is to provide a robust approach for predicting this premature failure of bolted joint due to initial gaps in assembly. VDI 2230 industry guideline for fastener assessment does not account for bending effect due to initial gap. To address this limitation, a “Coupled Analytical and FEA based” approach is developed to accurately capture initial bending moment and its effect on distribution of loads between the engaged threads. Results with initial gap show that there is a significant non-uniform distribution of shear forces on engaged threads, which reduces safety margins by 50% when compared with no-gap condition. The proposed approach was validated with experimental results on a sub-assembly of power electronic device. The authors expect this body of work will enable the readers to identify and mitigate the risk of bolted joint failure in compact assemblies like those in powder-dense EV and allied applications where initial gap in assembly is possible due to presence of multiple part tolerances (e.g., Choke, PCB, housing standoff etc.) and threads are present in soft material (e.g., copper busbar). Also, gap closure with sufficient clamping is desired for low contact resistance and high electrical performance.
Kar, Tanumoy, Shaikh, Rahil, Singh, Punit, Verma, Avinash
Simulation of Riveting Process on PCB and Comparison with Strain Gauge Measurements2022-28-035410/5/2022
Riveting is a process used to fasten printed circuit board to housing that offers several advantages compared to screws. This involves a cylindrical pin that protrudes from the housing being compressed with a concave tool to produce a rivet head that fills the PCB hole and holds it in place over service life of the component. The process as performed currently in-house uses parameters that have not been optimized. Testing has revealed that the process is subjecting the PCB to surface strains higher than 1000μɛ which is the limit as recommended by standards. Exceeding this limit reduces the reliability of electrical components and increases risk of field failures. This risk can be mitigated by improving the riveting process parameters to prevent high strain from reaching components. Having a finite element model for high deformation problems is an essential prerequisite to explore riveting process improvement. So the first goal is to identify a finite element procedure that converges well for large deformation problems and validate it with physical testing in terms of PCB strain, reaction force on tool and PCB hole filling level. Validation would also involve modeling strain gauges and placing them strategically on the PCB to ensure good comparison with test results. Then, suggestions need to be proposed to improve the riveting process based on simulations.
Krishna, Vikram, Faller, David, Andibur, Roman, Palaparthi, Kishore, Deckhardt, Celina, Gurudatt PhD, Balepur
Fretting Fatigue Damage and Life Evaluation of Cylinder Head Gasket Using Deviotoric Strain Amplitude-Based Parameter Corrected for Surface Wear Damage03-16-04-00249/21/2022
Fretting is a surface damage phenomenon and is typically observed at the contact interfaces such as bolted, gasketed joints, and the like. It occurs due to the combined effect of normal and tangential loads, which produces a small-amplitude relative sliding between two components that are held together using clamping forces. Fretting-related failures are also observed in multiple components of an internal combustion engine. This article presents the fretting fatigue damage evaluation of a single layer head gasket using a relative new approach, i.e., deviatoric strain amplitude-based method, further combined with the Ding’s empirical parameter D fret2. Corresponding fretting damage results are compared with the traditional approach based on the Ruiz’s parameter F1. To evaluate the consistency in the predicted results, the correlation study is carried out for three head gaskets of three different high horsepower engine platforms and very good correlation is observed between F1 damage results, fatigue life results obtained using the deviatoric strain amplitude-based parameter corrected for Ding’s parameter, D fret2, and the actual fretting damage observed on the actual head gasket. Stabilized stress-strain results obtained using multilinear kinematic hardening model (MKIN) are considered for the fatigue life evaluation. Further, alternative approach based on the “fretting limit line” is also proposed for simpler absolute and comparative fretting fatigue damage evaluation across the different designs. Overall, as demonstrated in this work, deviatoric strain amplitude-based parameter combined with Ding’s parameter, D fret2, is an effective approach toward the absolute and comparative fretting fatigue damage and associated life evaluation of actual engine components.
Ozarde, Amit Prakash, McNay, Gene H., Gautam, Sachin S.
Padded Self-Piercing Riveting (P-SPR) on Magnesium High Pressure Die Casting2022-01-02493/29/2022
Padded self-piercing riveting (P-SPR) is a newly developed multi-material joining technology to enable less ductile materials to be joined by self-piercing riveting (SPR) without cracking. A deformable and disposable pad was employed to reduce the stress distribution on the bottom surface by supporting the whole bottom sheet continuously during rivet setting process. To verify the P-SPR process, 2.0mm thick 6061-T6 wrought aluminum was joined with 3.2mm thick coated AM60B magnesium high pressure die casting (HPDC) by using 1.0mm thick dual-phase 600 (DP600) steel as the pad. Regular SPR processes with 2 different die geometries were studied as a comparison. Compared to the regular SPR processes, P-SPR demonstrated advantages on coating protection, crack mitigation and joint strength.
Liu, Yuchao, Wang, Gerry, Weiler, Jonathan
U-Bolt Pre-Load and Torque Capacity Determination Using Non-Linear CAE2022-01-07733/29/2022
This paper presents a method of using CAE to determine the pre-load and torque applied to a U-Bolt rear Spring Seat. In this paper it is review two U-bolt design and the stresses generated by the pre-load torque applied, based in this study a process to determine the minimal preload and the torque is discussed. By this process it is possible to determine the minimum Torque and the correct pre-load in the U-Bolt element and assuring the correct fastening of the components avoiding over stress in the Bar elements.
Martinez Laurent, Juan Carlos, Carrasco, Marco
Development and Deployment of Bolted Joint Integrity Evaluation for Automotive Suspension Joints2022-01-07613/29/2022
Bolted joints are the most used joints in automotive suspension assemblies. They are expected to retain the strength over the course of useful life of the vehicle and contribute to durability in a big way through reduction of stress amplitudes. Any sort of loosening or slip or breakage in these joints can lead to noise or catastrophic failures. In the past, such issues were addressed through thumb rules and design guidelines. However, with the focus on first-time right tests with reduced validation time it has become important to upfront predict the suspension joint integrity through simulation. Toward this objective, a novel approach was developed to simulate the suspension joint integrity for bolted joints. This approach considers various parameters like bolt preload, tolerance stackup of the parts in the joint, coefficients of friction of various interfaces, quality of contact and effect of deformation at the thread interface on joint integrity. Also, key parameters like percentage of bolt preload utilized in compression of bolted joint and contact opening values were monitored in joint integrity analysis. With the help of this method, it was possible to correlate prediction of joint slip for bolted suspension joint in vehicle durability test. Understanding of variation of joint performance w.r.t. above parameters enabled quick solutions to make the joints more robust. Thereafter this method was applied to other suspension joints in the vehicle to evaluate joint integrity in a reliable manner which was also corroborated in the test. This paper will outline and discuss in detail on above points. It will propose the method and criteria for judging bolted joint integrity.
Chaudhari, Varun N., Nagappan, Rajkumar, Kangde, Suhas, Londhe, Abhijit
Influence of Manufacturing Processes on the Structural Behavior of Truck Frame Rail Sections2022-01-07543/29/2022
The sequence of manufacturing processes involved in the making of truck frame rail sections leave a certain amount of imperfections in the form of plastic deformation and residual stresses in it. These residual stresses along with the externally induced loading stresses together should not be allowed to cross the yield limit of the frame material as it leads to premature failure of frame rail before giving its expected life. One such manufacturing process inducing premature failure is studied in detail using experimental analyses and presented in this paper. The kink bending process employed on the already formed and bolt hole punched C section frame rail, leads to plastic deformation and material crowding around the bolt hole located near the kink bend area of the frame flange. Experimental techniques such as Three Dimensional (3D) Laser Scanning and X-Ray Diffraction (XRD) were employed to assess the extent of plastic deformation and the residual stresses around the bolt hole surface respectively. It was observed that there is a significant loss of surface contact around the deformed bolt hole area and the presence of tensile residual stresses crossing the yield limit of the material on the bolt hole surface, which in turn lead to early initiation of frame crack on the bolt hole surface during proving ground trials. Hence, it is inferred from the study that any automotive designer should look for eliminating those processes inducing imperfections in critical areas or at least relocate the bolt holes/bolted joints away from those critical areas to avoid premature failure of truck frame rail sections.
K, Chinnaraj, KR, Balaji, Gopal, Gopi
Fatigue Endurance Limit of Fasteners in Automotive Application2022-01-02603/29/2022
Fasteners, commonly used in automotive industry, play an important role in the safety and reliability of the vehicle structural system. In practical application, bolted joints would never undergo fully reversed loading; there always will be positive mean stress on bolt. The mean stress has little influence on the fatigue life if the maximum stress is lower than a threshold which is near the yield stress of the bolt. However, when the sum of the mean stress and the stress amplitude exceeds the threshold, the endurance limit stress amplitude decreases fast as the mean stress increases. The purpose of this paper is to research the fatigue endurance limit of a fastener and establish the threshold for safe design in automotive application. In order to obtain the fatigue endurance limit at different mean stress levels, various mechanical tests were performed on M12x1.75 and M16x1.5 Class 10.9 fasteners using MTS test systems. Results show that the fatigue failure mode of a bolt is different from that of uniaxial tensile failure mode while the fatigue endurance limit curves of the two specific fasteners are very similar. Through this study, a safe fastener design zone is proposed for automotive bolted joint design.
Mao, Jianghui, Lin, Barry, Wu, Zhijun
Powertrain NVH CAE Process Enhancement Using Non-linear Interaction Modelling2022-01-06153/29/2022
NVH CAE is considered as one of the aspects of engine component design process. Following the best practices for CAE throughout the industry is the current trend which tend to miss the fact of improving it as per the continuously evolving component designs. Continuous improvement is necessary in existing methods and procedures to enhance CAE methodologies. Correlation of CAE models with measurement results increases stakeholders’ confidence and further allows to try out various combinations to reduce product development cycle time as well as cost. Engine components are connected with each other at periphery through bolted connection with required torque. The existing global CAE modeling practices are evolved to represent the bolt connections at the designed location. However, these practices miss the stiffness offered by the interface zone between bolts. Current study is focused on improvement of existing automotive connection modelling method through inclusion of non-linearity at the engine components interfaces. NVH simulation predictions have improved significantly through its incorporation in comparison with existing practices. The natural frequencies of the test parts in similar conditions are calculated using the computational model and correlated with experimental results. Validation of the proposed modeling method was carried out in two steps. First, modal vibrations tests were performed. Secondly, representative computations were performed and compared with measurements.
Singh, Aniruddh, Kumar, Vinay, Garg, Ankit Kumar
A New Approach to Check the Heath of Engine Mounting & Suspension Bolted Joints2022-01-06343/29/2022
The torque required to tighten any threaded joint is different from the necessary torque to untighten threaded bolt or nut, and it is not observed or widely known since this is a regular and straightforward operation. Typically the torque needed to untighten a newly tightened clamp is around 10% to 30% less than the torque to stretch it further. During tightening a threaded bolt, a significant amount of torque required to overcome friction in the threads and under the nut face. The proportion of the torque used to overcome frictional resistance depends upon the friction value. When we tighten a joint with a coefficient of friction of 0.12, only about approximately 14% of the torque required to stretch the fastener producing the clamp load with 86% of the torque is lost overcoming friction. The torque needed to pull the bolt always acts in the untightening direction, resulted in untightening torque lags behind the tightening torque. Sufficient preload has to be there in the bolted joint to meet service requirements. In this approach tightening torque, reading is Ton, and untightening torque is as Toff and then based on Ton & Toff reading preload is calculated in the bolt and checked with the requirement. If preload is not sufficient enough to serve in all load cases, then frictional parameters are to be changed to achieve necessary preload in a bolted joint. A case study of engine mounting bolt presented with this methodology.
Deshmukh, Sagar
Central Control of an Automated Riveting Machine and Robot Part Position with a Single CNC131993/10/2022
There exists a demand in the aerospace industry for highly configurable and flexible automated riveting cells to manufacture small to medium sized panels of complex geometries. To meet this demand Electroimpact has developed a manufacturing system consisting of a stationary Electro-squeeze C-frame riveter, coupled with a robot part positioner to present the component to the process head tool point. The C-frame can install a wide range of aerospace rivets and perform specialist functions including backside countersinking operations, giving potential for double flush fastening. The geometric limitations and high implementation costs of large cartesian based positioning barges or fixed jig tooling and moving gantry riveters are avoided when exchanged for a robot part positioner. To achieve the high levels of accuracy and repeatability required within the industry the robot part positioner is a KUKA KR1000L750 upgraded with EI proprietary Accurate Robot Technology (+/- 0.25 mm large volume global accuracy). Critical to the success of the system is high speed and seamless communication between the robot and C-frame, it is the details of this that will be explored within the paper. In summary this is achieved by deploying a Siemens 840D CNC as the singular central controller handling the robot motion control, riveting process and cell safety features. With twenty-seven individual servo driven axis? working in harmony to perform the core manufacturing functions the single 840D controller allows for a more efficient and simplistic control architecture when compared to the typical methodology of integrating a separate motion controller. A critical capability enabled by this approach is the ability to position components normal to the fastening axis via live sensor feedback at the tool point in real time. In circumstances where the system is reliant on the integration of a separate motion controller this type of closed loop feedback simply would not be possible.
Evans, Chris
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