Browse Topic: Fatigue

Items (3,077)

Low Cycle Thermo-Mechanical Fatigue Life of Solder Joints using Cohesive Zone Model

2024-28-0253To be published on 12/05/2024

A temperature dependent cohesive zone model considering the thermo-mechanical fatigue loadings are used to simulate and predict the failure process of solder joint interface in power electronics modules. Cohesive Zone Models (CZMs) are gaining popularity for modeling the fracture and fatigue behavior in various class of materials such as metals, polymers, ceramics, and their composite materials. Unlike the traditional fracture mechanics which considers concept of infinitesimal crack, CZMs assume a fracture process zone in which external energy is distributed in vicinity to propagating crack. In order to predict the fatigue-fracture process under thermo-mechanical cyclic loading, a damage accumulation variable is utilized. The calculation of damage is performed using a progressive mechanism, and the cohesive zone model is updated to reflect the present level of damage. The existing cohesive forces are influenced by both the current damage status and the extent of separation

Singh, Praveen Kumar, Sahu, Abhishek, Chirravuri, Bhaskara, Miller, Ronald

Durability Analysis for Off-Road Vehicle Stowage Systems

2024-01-3214

11/15/2024

ABSTRACT Durability analysis as applied to high mobility off-road ground vehicles involves simulating the vehicle on rough terrains and cascading the loads throughout the structure to support the verification of various components. For components within the hull structure, the rigid body accelerations of the hull are transformed to the component location producing a prescribed g-load time history. This modeling method works extremely well for items which are bolted in place but is inappropriate for stowage systems such as boxes and shelves where cargo can experience intermittent contact and impacts. One solution is to create a dynamic contact nonlinear finite element model of the stowage solution with supported cargo and subject them to the same acceleration profile. This approach effectively resolves the stresses needed to perform fatigue evaluations but is a computationally and labor intensive process. The resources required for single design point verification cannot be justified

Purushothaman, Nammalwar, Critchley, James, Hulings, Jessica, Joshi, Amarendra

DEVELOPMENT OF LABORATORY TESTING APPARATUS AND FATIGUE ANALYSIS FOR TRACKED VEHICLE RUBBER BACKER PADS

2024-01-3381

11/15/2024

ABSTRACT The first part of this paper will outline the conception of the testing apparatus (Figure 1), along with its operation and preliminary results. The second part of the paper will discuss a new methodology used to correlate the dependence of crack growth rate for strain crystallizing natural rubbers in terms of tearing energy. The tearing energy which depends on the type of elastomer, geometry and stress strain behavior of a particular specimen demonstrates a direct correlation with the crack growth rate at different R-ratios (= min tearing energy/max tearing energy). Figure 1 Schematic of the testing apparatus

Kujawski, Daniel, DiStefano, Daren, Bradford, William

Reduced-Order Modeling Method for Fatigue Life Predictions of Hybrid Electric Vehicle Batteries

2024-01-3373

11/15/2024

ABSTRACT The goal of this work is to develop an efficient numerical modeling method for the structural dynamic response of hybrid electric vehicle (HEV) batteries in order to support fatigue life predictions. The dynamics of HEV battery packs are known to feature very high modal density in many frequency bands. The high modal density combined with small, random structural variations among the cells (which are unavoidable in practice) can lead to drastic changes in the structural dynamics. Therefore, it may be important to perform probabilistic simulations of the structural dynamic response with cell-to-cell parameter variations in order to accurately predict the fatigue life of a battery pack. However, the computational time for obtaining forced response results for just a single sample of parameter variations with a finite element model can be on the order of a day. One approach to overcome this challenge is to generate parametric reduced-order models (PROMs). The novel approach is

Hong, Sung-Kwon, Epureanu, Bogdan I., Castanier, Matthew P.

DIGITAL TWIN FOR TANK TRACK ELASTOMERS: PREDICTING SELF-HEATING AND DURABILITY

2024-01-3642

11/15/2024

ABSTRACT In this work, Abrams tank track system T-158LL backer pad elastomer self-heating and fatigue behavior was characterized experimentally, and the backer pad design was digitally twinned to show how complex in-service conditions can be evaluated virtually. The material characterization included measurement of the thermal properties and dissipative characteristics of the rubber compound, as well as its fatigue crack growth rate curve and crack precursor size. The analysis included 1) a structural finite element analysis of the backer pad in operation to obtain the load history, 2) a thermal finite element analysis to obtain steady-state operating temperature distribution within the backer pad, and 3) a thermo-mechanical fatigue analysis using the Endurica CL fatigue solver to estimate the expected service life and failure mode of the backer pad. As validation, experiments were conducted on the backer pad to measure operating temperature, fatigue life, and failure mode over a

Mars, William V., Castanier, Matthew, Ostberg, David, Bradford, William

SAMPLING-BASED RBDO USING STOCHASTIC SENSITIVITY AND DYNAMIC KRIGING FOR BROADER ARMY APPLICATIONS

2024-01-3301

11/15/2024

ABSTRACT The University of Iowa has successfully developed Reliability-Based Design Optimization (RBDO) method and software tools by utilizing the sensitivity analysis of the fatigue life; and applied RBDO to Army ground vehicle components to obtain reliable optimum designs with significantly reduced weight and improved fatigue life. However, this method cannot be applied to broader Army application problems due to lack of sensitivity analysis in many application areas. Thus, for broader Army applications, a sampling-based RBDO method using surrogate model has been developed recently. The Dynamic Kriging (DKG) method is used to generate surrogate models, and a stochastic sensitivity analysis is used to compute the sensitivities of probabilistic constraints with respect to independent and correlated random variables. Once the DKG method accurately approximates the responses, there is no further approximation in the estimation of the probabilistic constraints and stochastic sensitivities

Choi, K.K., Lee, Ikjin, Zhao, Liang, Noh, Yoojeong, Lamb, David, Gorsich, David

A Framework for Modeling and Simulation of Tracked Vehicles of High Mobility

2024-01-3232

11/15/2024

ABSTRACT This paper presents a modeling and simulation framework for tracked vehicles for ride comfort and load prediction analysis. The development began with the identification of the key issues such as formulations, integration schemes and contact (with friction) modeling on which the comparative studies are conducted. Based on the results of the investigations, the framework and process for the modeling and simulation of tracked vehicles are established and appropriate algorithms for contact and friction are developed. To facilitate the modeling and simulation process, a Python-based modeling environment was developed for process automation, design optimization and design of experiment. The developed framework has been successfully applied to the dynamic load predication of a M1A1 based Joint Assault Bridge (JAB). The parameter optimization enabled with the Python-based process automation tool helps improve the design and modification of vehicles for significantly improved fatigue

Song, Peilin, Melick, Pete, Horchner, James

INCREASING POWER DENSITY BY ADVANCED MANUFACTURING, MATERIALS, AND SURFACE TREATMENTS

2024-01-3595

11/15/2024

ABSTRACT Track vehicle Final Drive torque transferring capacity is constrained by the availability of packaging space, weight constraints, and material / heat treat properties. These constraints create a paradigm where as the increase in load due to weight growth is inversely related to life due to fatigue. Funded under Phase II SBIR contract W56HZV-13-C-0056, Loc Performance Products, Inc. (Loc) developed manufacturing processes aligned to key selected materials and surface treatments to break through this paradigm. The results of the SBIR efforts produced an optimized Final Drive design that addressed the increasing Gross Vehicle Weight (GVW) of the Bradley Fighting Vehicle while maintaining the current Final Drive packaging space, reducing lifecycle cost and maximizing performance in terms of power density and extending the life of the product

Militello, Anthony, Fowlkes, Edward

PREDICTING THE LIFE OF MILITARY VEHICLE COMPONENTS IN THE PRESENCE OF DEFECTS

2024-01-3200

11/15/2024

ABSTRACT When the components of a military vehicle are designed, consideration is given to long term durability under repeated mission applications. In reality, surface and subsurface defects have always existed in weldments, forgings, and castings. These defects came from the manufacturing process or nucleated during the life of the vehicle. These defects may grow under repeated operations, resulting in ultimate failure of parts well before the design life is achieved. In such situations, a design based on crack initiation alone will not suffice, and a fracture mechanics based fatigue should also be included to predict the design life of a part accurately. In this paper a methodology is given on how to predict the available design life given the presence of defects in different parts of a military vehicle. An example will be provided with the process to demonstrate each step of the process

Porter, William De

A ROBUST DURABILITY PROCESS FOR MILITARY GROUND VEHICLES

2024-01-3122

11/15/2024

ABSTRACT BAE Systems has departed from traditional design rules of thumb and implemented a full-vehicle durability fatigue life analysis process at the design concept level to support lighter weight component designs. The durability process includes derivation of test duty cycles, generation of virtual loads from vehicle dynamic simulations, cascading of hundreds of channels of suspension attachment loads, and prediction of accumulated damage/fatigue life for both quasi-static and transient responses using a finite element vehicle structural model. The fatigue analysis process is typically deterministic, however the stochastic nature of the loads, material properties, and build variations should also be considered to ensure a robust durability process. The process is demonstrated on a heavy wheeled-vehicle platform using a generic duty cycle with examples shown at each stage of the process. This study additionally demonstrates the effects of variability of loads, materials, and

Purushothaman, Nammalwar, Jayakumar, Paramsothy, Critchley, James, Datta, Sandip, Pisipati, Venkat

MECHANICAL BEHAVIOR AND FATIGUE STUDIES OF RUBBER COMPONENTS USED IN TRACKED VEHICLES

2024-01-3207

11/15/2024

ABSTRACT In this study, a styrene butadiene rubber, which is similar to the rubber used in road wheel backer pads of tracked vehicles, was investigated experimentally under monotonic and fatigue loading conditions. The monotonic loading response of the material was obtained under different stress states (compression and tension), strain rates (0.001/s to 3000/s), and temperatures (-5C to 50C). The experimental data showed that the material exhibited stress state, strain rate and temperature dependence. Fatigue loading behavior of the rubber was determined using a strain-life approach for R=0.5 loading conditions with varying strain amplitudes (25 to 43.75 percent) at a frequency of 2 Hz. Microstructural analysis of specimen fracture surfaces was performed using scanning electron microscopy and energy dispersive x-ray spectroscopy to determine the failure mechanisms of the material. The primary failure mechanisms for both loading conditions were found to be the debonding of particles on

Brown, H.R., Bouvard, J.L., Oglesby, D., Marin, E., Francis, D., Antonyraj, A., Toghiani, H., Wang, P., Horstemeyer, M.F., Castanier, M.P.

METALLIC COMPOSITE MATERIALS FOR AFFORDABLE & RELIABLE THERMAL MANAGEMENT OF HIGH POWER DEVICES

2024-01-3178

11/15/2024

ABSTRACT Lower cost aluminum silicon carbide (Al-SiC) metal matrix composite (MMC) produced by stir-casting is emerging as an important material in cost effectively improving the reliability of high power electronic devices; e.g. electronic (IGBT) baseplates, thermal spreaders & stiffeners for flip-chip microelectronics, and heat slugs or MCPCB base layers for high brightness LEDs. This paper will review the properties and competitive cost of these new Al-SiC materials as well as the ability to tailor the coefficient of thermal expansion (CTE) of the Al-SiC to minimize thermal fatigue on solder joints and reduce component distortion. The impact on the final component cost through the use of conventional forming techniques such as (a) rolling sheet followed by stamping, and, (b) die casting, will be described, as will be the opportunity of eliminating a thermal interface material (TIM) layer by integrating the thermal spreader with the heat sink for high power microelectronic packages

Drake, Allen, Schuster, David, Skibo, Michael

GVSETS 2020 PAPER: FATIGUE-FOCUSED WELD ASSEMBLY OPTIMIZATION

2024-01-3834

11/15/2024

ABSTRACT This work presents the development and application of an optimization algorithm for simultaneously improving the fatigue life and minimizing a representative manufacturing cost when assembling a ground combat vehicle. High stress in the occupied space of the weld decreases the fatigue life of the structure; therefore, by minimizing the weld’s exposure to high stresses, the structure’s life can be improved. The new capability for simultaneously improving the fatigue life of a welded structure while reducing a manufacturing cost is demonstrated by considering the welding of a representative panel of a v-hull. Selections are made for the weld placement, the weld type, and the type of filler material, in order to minimize exposure to high stresses and therefore maximize fatigue life. In addition to the stress evaluation, the optimization considers manufacturing cost as another objective in parallel. The final evaluation provides an assembly design to increase the fatigue life and

Mayhood, Carly, Vlahopoulos, Nickolas

INVESTIGATION OF THE DURABILITY TRANSFER CONCEPT FOR VEHICLE PROGNOSTIC APPLICATIONS

2024-01-3209

11/15/2024

ABSTRACT Vehicle prognostics are used to estimate the remaining useful life of components or subsystems, based on a limited number of measured vehicle parameters. Ideally, sensors would be available for every component and failure mode of interest, such that accurate data could be measured and used in prognostic estimates. However, this is impractical in terms of the number of sensors required and the costs to install such a system and maintain its integrity. A better solution is to relate the loading on a specific component to more generic vehicle behavior. This paper reviews a methodology referred to as the “Durability Transfer Concept”, which suggests that damage, or severity of usage, at various points of interest on a vehicle can be predicted simply from measured accelerations at some nominal location – a wheel axle, for example. Measured accelerations are double integrated to get displacements. Those displacements are then filtered using the Rupp or Lalanne method. A transfer

Halfpenny, Andrew, Hussain, Shabbir, McDougall, Scott, Pompetzki, Mark

Reliability Prediction Using Additive Weibull Model

2024-01-5101

11/05/2024

This paper presents additive Weibull reliability model using customer complaints data and finite element fatigue (FEA) analysis data. Warranty data provides insight into the underlying customer issues. Reliability engineers prepare a prediction model based on this data to forecast the failure rate of components. However, warranty data has certain limitations with respect to prediction modeling. The warranty period covers only the infant mortality and useful life zone of a bathtub curve. Thus, predicting with solely warranty data generally cannot provide results with desired accuracy. The failure rate of wear-out components is driven by random issues initially and wear-out or usage-related issues at the end of the lifetime. For accurate prediction of failure rate, data need to be explored at wear-out zone of a bathtub curve. Higher cost always limits the testing of components until failure, but FEA fatigue analysis can provide the failure rate behavior of a part much beyond the warranty

Koulage, Dasharath Baliram, Mondal, Kanchan, Manerikar, Dattatray Shriniwas

Numerical and Experimental Investigation of Water Cooled Reciprocating Air Compressor Used in Automotive Applications

2024-28-0014

10/17/2024

Most of the heavy commercial vehicles are installed with Pneumatic brake system where the medium is a pressurized pneumatic air generated with the reciprocating air compressor. Heating is an undesirable effect of the compression process during loading cycles as reciprocating air compressors are concerned. Therefore it is necessary to reduce the delivery air temperature of compressor for safer operation of downstream products. The present investigation deals with the measurement of the delivery air temperature of a typical 318 cc water cooled compressor. A through steady state conjugate heat transfer analysis is conducted for the given speed and with the specification cooling water flow rate to predict the delivery air temperature. Pressure drop across the cooling water flow path has been measured and optimum flow rate is arrived to meet the design requirement. The results of characteristic analysis and comparative research show that the cooling system can obviously reduce the cylinder

N, Prabhakar, V A, Sahaya Irudayaraj, Raj, Amal, T, Sukumar

Guidelines for Design of Digital Fiber Optic Link Loss Budget Methodology

AIR6113 (Current)

10/07/2024

This document draws from, summarizes, and explains existing broadly accepted engineering best practices. This document defines the process and procedure for application of various best practice methods. This document is specifically intended as a standard for the engineering practice of development and execution of a link loss power budget for a general aerospace system related digital fiber optic link. It is not intended to specify the values associated with specific categories or implementations of digital fiber optic links. This document is intended to address both existing digital fiber optic link technology and accommodate new and emerging technologies. The proper application of various calculation methods is provided to determine link loss power budget(s), that depend on differing requirements on aerospace programs. A list of parameters is provided as guidance for aerospace fiber optics applications along with a check list to help assure that appropriate parameters and

AS-3 Fiber Optics and Applied Photonics Committee

Stress Field near Crack Tips in Pressurized Thick-Walled Cylinders with Single and Multiple Cracks in Linear Elastic Fracture Mechanics: Analytical and Numerical Analysis of Stress Field and Crack Behavior

05-18-01-0004

10/04/2024

Arrays of radial cracks often appear at the bore of pressurized cylinders, posing potential safety risks and leading to possible structural failures. This article presents an analytical approach to evaluate the stress field arising from single or multiple uniform radial cracks in thick-walled pressurized cylinders within the context of linear elastic fracture mechanics (LEFM) under mode-I loading. This formulation is based on the fundamental equations of elasticity and approximations of stress intensity factors (SIF) reported in the literature. Hence, the SIF were revisited and their range of validity was highlighted. The study considers two types of internal pressure loading: one applied only to the cylinder’s inner surface with no pressure on the crack faces and another applied to both the inner surface and the crack faces. The influence of the number and length of cracks relative to cylinder thickness on the stress field is analyzed. A finite element model of the pressurized vessel

Methia, Mounir, Benslimane, Abdelhakim, Bechir, Hocine, Aït Hocine, Nourredine

Additively Manufactured Lightweight Automobile Cylinder Head—A New Process for Structural Optimization from Concept to Validated Hardware

03-18-01-0003

09/25/2024

Reducing vehicle weight is a key task for automotive engineers to meet future emission, fuel consumption, and performance requirements. Weight reduction of cylinder head and crankcase can make a decisive contribution to achieving these objectives, as they are among the heaviest components of a passenger car powertrain. Modern passenger car cylinder heads and crankcases have greatly been optimized in terms of cost and weight in all-aluminum design using the latest conventional production techniques. However, it is becoming apparent that further significant weight reduction cannot be expected, as processes such as casting have reached their limits for further lightweighting due to manufacturing restrictions. Here, recent developments in the additive manufacturing (AM) of metallic structures is offering a new degree of freedom. As part of the government-funded research project LeiMot [Lightweight Engine (Eng.)] borderline lightweight design potential of a passenger car cylinder head with

Kayacan, Can, Pischinger, Stefan, Ahlborn, Klaus, Bültmann, Jan

Knowledge Push Mechanism of Rolling Bearing Fault Diagnosis Employing Deep Residual Network Architecture

2024-01-6004

09/11/2024

Rolling bearings play a critical role in rotating machinery, with their fatigue life directly impacting equipment’s operational reliability. This underscores the significant engineering application value of “fault diagnosis” (FD) technology for rolling bearings in mechanical, automation, and aerospace domains. Literature reviews highlight that a substantial portion of failures in machinery such as jet turbine engines, wind turbines, gear reducers, and induction machines are attributable to bearing issues. Early fault detection and preventive maintenance are therefore imperative for ensuring the smooth operation of rotating machinery. This paper focuses on rolling bearings, delving deep into FD technology using machine learning principles. It analyses the structure and common failure modes of rolling bearings, discussing an FD method based on machine learning. Specifically, the SE-DRN (“squeeze-exclusion deep residual network”) approach is employed, leveraging “variational modal

Muin, Abdullah-Al, Khan, Shahrukh, Miah, Md Helal

Computer-Aided Engineering Approach to Optimize Hydroformed Exhaust Gas Recirculation Tube under Thermal Load

2024-01-5086

08/30/2024

This study emphasizes the importance of computer-aided engineering (CAE) approach in optimizing exhaust gas recirculation (EGR) tube under thermal load. With exhaust gases generating high temperatures, the EGR tube experiences increased stress and strain, posing challenges to its structural integrity. Moreover, the cyclic heating and cooling cycles of the engine imposes thermal fatigue, further compromising the tube’s performance over time. To address these concerns, the paper introduces a comprehensive CAE methodology for conducting factor of safety analysis. The nonlinear thermal analysis is performed on the assembly as due to high temperatures the stresses cross the yield limit. The strain-based approach is used to calculate the factor of safety. Moreover, a comprehensive case study is presented, illustrating how design modifications can enhance the thermal fatigue factor of safety. By adjusting parameters such as thickness and routing, engineers can mitigate thermal stresses and

Munde, Ganesh, Chattaraj, Sandip, Hatkar, Chandan, Godse, Rushikesh

Effect of nanostructuring of nodular cast iron on the static mechanical properties and fatigue life of commercial vehicle brake spiders

2024-36-0312

08/09/2024

The demand for enhanced safety and extended lifespan of brake systems prompts the investigation to increase the static mechanical properties and fatigue resistance of commercial vehicle brake spiders through the incorporation of niobium nanoparticles into a cast iron alloy. This study aims to improve the material structure as well as the static and dynamic mechanical properties of the component. Chemical, microscopic, and mechanical analyses were conducted in samples of the nanostructured alloy and in the spider. A durability test was performed using a structural bench called “Chuker” to assess the potential increase in fatigue life. The Chuker is capable of simulating a real-world brake system condition, including torque magnitudes up to 17.5 kNm, which are the highest to be withstand by the designed brake power. This torque replicates the brake system activation during a vehicle emergency braking. The spiders manufactured with the nanostructured alloy exhibited most uniform

Titton, Angelo Pradella, Tuzzin, Matheus, Lopes, Carlos H. R., Marcon, Lucas, Boaretto, Joel, Klein, Aloísio N., Cruz, Robinson C. D.

Application of Neural Networks for Real-Time Decision Support in Virtual Approval of Brake Components

2024-36-0306

08/09/2024

This study aims to present a virtual numerical validation procedure for durability in brake system components, using artificial neural networks and based on experimental bench tests. The study focus was concentrated on the drum brake spider component, responsible for mechanically connecting the brake system subassemblies. To develop the validation procedure, engineering software such as ABAQUS, Fe-Safe, Minitab, and MATLAB was used. These were crucial for carrying out stress analyses, statistical data validation, and construction of an Artificial Neural Network (ANN) capable of predicting finite element responses, fatigue life, and supporting real-time decision-making for structural validation of mechanical components. The results obtained from these tools allowed the calibration of a numerical virtual model using the Finite Element Method (FEM) based on mechanical theories and results obtained in bench tests with the brake system, thus, a finite element database was generated for the

Marcon, Lucas, Vieceli, Alexandre, Corso, Leandro

A Fatigue Damage Spectrum-Based Approach to Vibration Durability Test for Vehicle Batteries

02-17-03-0016

08/06/2024

For the vibration durability bench test of commercial vehicle batteries, it is essential to have accurate test specifications that exhibit high robustness and reasonable acceleration characteristics. This study evaluates the impact of different battery frame systems on the vibration response of the battery body, as determined by road load spectrum test results of a commercial vehicle battery system. It also confirms the variations in the external environmental load. Utilizing the response spectrum theory, a comprehensive calculation method for the fatigue damage spectrum (FDS) of batteries is developed. The time domain direct accumulation method, frequency domain direct accumulation method, and frequency domain envelope accumulation method are all compared. Analysis of kurtosis and skewness reveals that when the load follows the super-Gaussian distribution characteristics, the time domain direct accumulation method should be used to calculate the fatigue damage spectrum to minimize

Yan, Xin, Guo, Dongni, Wan, Xiaofeng, Sun, Jiamei, Quan, Xinhui, Wang, Ying

Liftgate Slam by Bilinear Quasistatic Approach Using Modal Transient Method under Equivalent Static Loads

2024-01-5077

08/05/2024

Automotive closure slam is the most crucial attribute affecting the closure structure and its mountings on BIW due to its high occurrence in real-world usage. Thus, virtual simulation of closure slam becomes necessary and is generally carried out using explicit codes with associated technical hitches like all-requisite inputs availability, FE modeling and analysis techniques, substantial human effort, high solution time, human and computational resource competence, or even access to suitable expensive explicit FE solver. Hence it becomes challenging to virtually analyze the design at every design phase of product development cycle under strict timelines leading to possibilities of both over- and under-designed parts, sometimes resulting in physical testing or even field failures. So, the need for an alternative simplified representation of closure slam, addressing the typical issues faced during explicit dynamic simulation and producing acceptable analysis outputs, gains significance

Chatterjee, Suprakash

Uniaxial Stress and Strain Analysis of a Notched Component Made of Cast Irons

05-18-01-0001

08/02/2024

This article investigates the deformation mechanics of cast iron and its implications for notch analysis, particularly in the automotive industry. Cast iron’s extensive use stems from its cost-effectiveness, durability, and adaptability to various mechanical demands. Gray, nodular, and compacted graphite cast irons are the primary types, each offering unique advantages in different applications. The presence of graphite, microcracks, and internal porosity significantly influences cast iron’s stress–strain behavior. Gray and compacted cast iron display an asymmetrical curve, emphasizing low tensile strength and superior compression performance due to graphite flakes and crack closures. Nodular cast iron exhibits a symmetrical curve, indicating balanced mechanical properties under tension and compression. The proposed simplified macrostructural approach, based on monotonic stress–strain, aims to efficiently capture graphite and crack closure effects, enhancing compressive strength and

LaCourt, Cameron, Lee, Yung-Li, Gu, Randy

Comparison of Low Cycle Fatigue Crack Propagation Methods for Turbine Exhaust Case

2024-01-6002

07/24/2024

The aerospace industry heavily relies on NASGRO as a standard method for crack propagation analysis, despite encountering challenges due to variations in stress gradients across flight missions. In response to this issue, this paper introduces a pioneering methodology that integrates stress gradients at each time point throughout a mission, computed cycle by cycle using NASGRO. The study meticulously evaluates the feasibility and efficacy of this approach against established industry-standard procedures, focusing on the critical topic of low cycle fatigue (LCF) and underscoring the significance of damage-tolerant design principles. The methodology encompasses the design of an H-sector in Ansys Workbench, the execution of stress analysis for a typical flight mission profile, and the systematic extraction of stress gradients for each cycle at the pivotal crack nucleation point. Subsequently, NASGRO is employed to estimate life cycles using both industry-standard baseline methodologies

Karandikar, Rishi Suhas, Kumar, Niraj

Carbon Steel, Wire Spring Quality Music Wire 0.70 - 1.00C Cold Drawn

AMS5112N (Current)

06/24/2024

This specification covers a carbon steel in the form of wire supplied as coils, spools, or cut lengths (see 8.2

AMS E Carbon and Low Alloy Steels Committee

Effect of Fatigue Loads on behavior of 2024 Aluminum for Aircraft Hydraulic Applications

2024-26-0431

06/01/2024

Hydraulic systems in aircraft largely comprise of metallic components with high strength to weight ratios. Some examples of such material include Aluminum and Titanium alloys which are typically chosen for low and high-pressure applications respectively. For aircraft fluid conveyance products, hydraulic conduits are fabricated by axisymmetric turning to support flow conditions. The hydraulic conduits can have grooved interfaced design within for placement of elastomeric sealing components. This article presents a systematic study carried out on common loads experienced by fluid carrying conduits and the failure modes induced. Firstly, a static structural analysis was carried out on each of the geometries of the test articles to identify the locations having areas of high stress concentration. Test articles of various wall thicknesses and internal diameters were pressure impulse tested at different conditions of side loads to identify cycle numbers till failure and failure locations. On

Paidimarri, Vishal, Jacob, Krupa, Harish, Uppu, Hovis, David

A Multi-Scale Computational Scheme for Prediction of High-Cycle Fatigue Damage in Metal Alloy Components

2024-26-0430

06/01/2024

High-cycle fatigue damage causing micro-crack initiation is a critical concern in aerospace structural components and alloys due to intense thermo-mechanical stress and vibration. Vibration or overload/impact can initiate small cracks near the stress concentration zones. These cracks may expand erratically before being detectable in subsequent inspections, emphasizing the need to predict the effects of usage and aging on components. This predictive ability would significantly aid material refinement, design enhancements, and inspection planning. Prediction of fatigue damage leading to the formation of cracks is a great challenge for many reasons, including microstructure anisotropy and uncertainties in complex stress states compared to design stress used in testing and qualifying a component. These uncertainties undermine inspection reliability and effectiveness. The elastic moduli of the material are considered isotropic and homogeneous at the macroscopic level of continuum plasticity

Kumar, Ravi, D S, Karan, Roy Mahapatra, Debiprosad

A Methodology for Accelerated Thermo-Mechanical Fatigue Life Evaluation of Advanced Composites

2024-26-0421

06/01/2024

Thermo-mechanical fatigue and natural aging due to environmental conditions are challenging to simulate in an actual test with advanced fiber-reinforced composites, where their fatigue and aging behavior are little understood. Predictive modeling of these processes is challenging. Thermal cyclic tests take a prohibitively long time, although the strain rate effect can be scaled well for accelerating the mechanical stress cycles. Glass fabric composites have important applications in pipes, aircraft, and spacecraft structures, including microwave transparent structures, impact-resistant parts of the wing, fuselage deck and many other load-bearing structures. Often additional additively manufactured features and coatings on glass fabric composites are employed for thermal and anti-corrosion insulations. In this paper, we employ a thermo-mechanical fatigue model based on an accelerated fatigue test and life prediction under hot-to-cold cycles. Thermo-mechanical strain-controlled stress

Kancherla, Kishore Babu, B S, Dakshayini, Raju, Benjamin, Roy Mahapatra, Debiprosad

Failure Analysis of Cryogenically Treated and Gas Nitrided Die Steel in Rotating Bending Fatigue

05-17-02-0014

04/24/2024

AISI H13 hot work tool steel is commonly used for applications such as hot forging and hot extrusion in mechanical working operations that face thermal and mechanical stress fluctuations, leading to premature failures. Cryogenic treatment was applied for AISI H13 steel to improve the surface hardness and thereby fatigue resistance. This work involves failure analysis of H13 steel specimens subjected to cryogenic treatment and gas nitriding. The specimens were heated to 1020°C, oil quenched followed by double tempering at 550°C for 2 h, and subsequently, deep cryogenically treated at −185°C in the cryochamber. Gas nitriding was carried out for 24 h at 500°C for 200 μm case depth in NH3 surroundings. The specimens were subjected to rotating bending fatigue at constant amplitude loading at room temperature. Measurement of surface roughness, hardness, and microstructural analysis indicated improved fatigue life for cryogenically treated specimens as compared to gas nitride, which could be

Shinde, Tarang, Mutalikdesai, Sachin, Jomde, Amit, Shamkuwar, Sonal

Dynamic Performance Optimization of Ball Joints with Cross Groove for Automotive Driveshaft System

2024-01-2438

04/09/2024

The ball joint with cross groove offers both angular and plunging motion. When transmitting the same torque, the cross groove ball joint is lighter than other plunging Constant Velocity Joints (CVJs). It is crucial for the design of the joint and enhancing the contact fatigue life of the raceway to accurately estimate component loads of the ball joints with cross groove. In this study, the transmission efficiency of the joint and the peak value of contact force between ball and the track are used as evaluation indexes for characterizing dynamic performance of the joint. A multibody dynamic model of the joint is established to calculate its dynamic performance. In the model, the contact properties and friction characteristics of the internal structures were modeled, and a nonlinear equivalent spring and damping model was adopted for estimating the contact force. The transmission efficiency loss of the cross groove joint was measured and compared with the calculated values. Taking

Zhan, Haojing, Wan, Lixiang, Wu, Xiaoyong, Hou, Qiufeng, Shangguan, Wenbin

Durability of Elastomeric Bushings Computed from Track-Recorded Multi-Channel Road Load Input

2024-01-2253

04/09/2024

The qualification requirements of automakers derive from track testing in which road load and moment inputs to a part in x, y and z directions are recorded over a set of driving conditions selected to represent typical operation. Because recorded histories are lengthy, often comprising many millions of time steps, past industry practice has been to specify simplified block cycle schedules for purposes of durability testing or analysis. Simplification, however, depends on imprecise human judgement, and risks fidelity of the inferred life and failure mode relative to actual. Fortunately, virtual methods for fatigue life prediction are available that are capable of processing full, real-time, multiaxial road load histories. Two examples of filled natural rubber ride bushings are considered here to demonstrate. Each bushing is subject to a schedule of 11 distinct recorded track events. Endurica EIETM map building procedures are first used together with a finite element solution to map the

Mars, William, Barbash, Kevin, Wieczorek, Matthew, Braddock, Scott, Goossens, Joshua, Steiner, Ethan

A Study on Fatigue Life Prediction Technique considering Bead Notch Shape in Arc Welding of Steel Components under Multi-Axial Load

2024-01-2257

04/09/2024

This study deals with the fatigue life prediction methodology of welding simulation components involving arc welding. First, a method for deriving the cyclic deformation and fatigue properties of the weld metal (that is also called ER70S-3 in AWS, American Welding Standard) is explained using solid bar specimens. Then, welded tube specimens were used with two symmetric welds and subjected to axial, torsion, and combined in-phase and out-of-phase axial-torsion loads. In most previous studies the weld bead’s start/stop were arbitrarily removed by overlapping the starting and stop point. Because it can reduce fatigue data scatter. However, in this study make the two symmetric weld’s start/stops exposed to applying load. Because the shape of the weld bead generated after the welding process can act as a notch (Ex. root notch at weld start / Crater at weld stop) to an applied stress. Accordingly, they were intentionally designed to cause stress concentrations on start/stops. A geometric 3D

Kim, Dooyoung, Kong, Ho Young, Park, Jaehong

A Method for Predicting Fatigue Life of Rubber Isolators at Power Spectral Density Load

2024-01-2261

04/09/2024

Rubber isolators are widely used under random vibrations. In order to predict their fatigue life, a study on the fatigue analysis methodology for rubber isolators is carried out in this paper. Firstly, taking a mount used for isolating air conditioning compressor vibrations as studying example, accelerations versus time of rubber isolator at both sides are acquired for a car under different running conditions. The acceleration in time domain is transformed to frequency domain using the Fourier transform, and the acceleration power spectral density (PSD) is the obtained. Using the PSD as input, fatigue test is carried for the rubber isolator in different temperature and constant humidity conditions. A finite element model of the rubber isolator using ABAQUS is established for estimating fatigue life, and model validity is verified through static characteristic testing. Dynamic responses of the rubber isolator at frequency domain are calculated if a unit load is applied. The estimated

Yao, Qishui, Li, Min, Zhang, Licheng, Yue, Zaiqin, Shangguan, Wen-Bin

Spectrum-Based Method for Fatigue Damage under Excitation of Sinusoidal Sweeps for Automotive Systems

2024-01-2260

04/09/2024

Vibration from a mechanical system not only produces unwanted noises annoying to people around, but also runs a risk of fatigue failure that would actually hinder its functionality. There are several forms of vibration depending on the sources of excitation forms. Mechanical systems with rotating components can be subjected to sinusoidal excitation due to the fact the center of mass is not perfectly aligned with the rotating axis. If the rotating speed is strictly ramping up or ramping down, this can create an excitation whose frequency is changing with time in a frequency range corresponding to the speeds swept. Compared with a single sinusoidal excitation, the issue with fatigue at swept sinusoidal excitation, is that as it sweeps through a wide frequency range, some swept frequencies will definitely coincide with the natural frequencies of the system. Certainly, the stress response exactly at the resonant frequency becomes the highest and could account for a lot of fatigue damage

Yang, Zane, Zhou, Lin

A Study on a Prognostics and Health Management (PHM) Based on Fracture Mechanics Using Deep Learning

2024-01-2248

04/09/2024

This paper presents deep learning-based prognostics and health management (PHM) for predicting fractures of an electric propulsion (eP) drivetrain system using real-time CAN signals. The deep learning algorithm, based on autoencoders, resamples time-series signals and converts them into 2D images using recurrence plots (RP). Subsequently, through unsupervised learning of DeepSVDD, it detects anomalies in the converted 2D images and predicts the failure of the system in real-time. Also, reliability analysis based on fracture mechanics was performed using the detected signals and big data. In particular, the severity of the eP drivetrain system is proportional to the maximum shear stress (τmax) in terms of linear elastic fracture mechanics (LEFM) and can be calculated by summarizing the relationship between cracks (a) and the stress intensity factor (KIII). During this process, the system status can be checked by comparing the stress intensity factor and fracture toughness (KIIIc), and

Moon, Byungwoo, Lee, SangWon, Nam, DongJin, Kim, Jeonghwan, Bae, JaeWoong, Shin, JeongMin

Method for Root Bending Fatigue Life Prediction in Differential Gears and Validation with Hardware Tests

2024-01-2249

04/09/2024

An advanced multi-layer material model has been developed to simulate the complex behavior in case-carburized gears where hardness dependent strength and elastic-plastic behavior is characterized. Also, an advanced fatigue model has been calibrated to material fatigue tests over a wide range of conditions and implemented in FEMFAT software for root bending fatigue life prediction in differential gears. An FEA model of a differential is setup to simulate the rolling contact and transient stresses occurring within the differential gears. Gear root bending fatigue life is predicted using the calculated stresses and the FEMFAT fatigue model. A specialized rig test is set up and used to measure the fatigue life of the differential over a range of load conditions. Root bending fatigue life predictions are shown to correlate very well with the measured fatigue life in the rig test. Also fatigue life predictions are shown to correlate well with validation tests carried out on a full-scale axle

DeJack, Michael A., Tichy, Richard

Efficient Fatigue Performance Dominated Optimization Method for Heavy-Duty Vehicle Suspension Brackets under Proving Ground Load

2024-01-2256

04/09/2024

Lightweight design is a key factor in general engineering design practice, however, it often conflicts with fatigue durability. This paper presents a way for improving the effectiveness of fatigue performance dominated optimization, demonstrated through a case study on suspension brackets for heavy-duty vehicles. This case study is based on random load data collected from fatigue durability tests in proving grounds, and fatigue failures of the heavy-duty vehicle suspension brackets were observed and recorded during the tests. Multi-objective fatigue optimization was introduced by employing multiaxial time-domain fatigue analysis under random loads combined with the non-dominated sorting genetic algorithm II with archives. While evaluating fatigue life within optimization loops, particularly for multiaxial random load fatigue in the time domain, is time-intensive, this study is to improve computational efficiency in two strategies: 1) the dynamic adjustment of target nodes from the

Tong, Jiachi, Meng, Dejian, Wang, Lei, Gao, Yunkai, Yang, James

A Special User Shell Element for Coarse Mesh and High-Fidelity Fatigue Modeling of Spot-Welded Structures

2024-01-2254

04/09/2024

A special spot weld element (SWE) is presented for simplified representation of spot joints in complex structures for structural durability evaluation using the mesh-insensitive structural stress method. The SWE is formulated using rigorous linear four-node Mindlin shell elements with consideration of weld region kinematic constraints and force/moments equilibrium conditions. The SWEs are capable of capturing all major deformation modes around weld region such that rather coarse finite element mesh can be used in durability modeling of complex vehicle structures without losing any accuracy. With the SWEs, all relevant traction structural stress components around a spot weld nugget can be fully captured in a mesh-insensitive manner for evaluation of multiaxial fatigue failure. For validation purposes, a set of spot-welded lab test specimens has been analyzed for demonstrating the mesh-sensitivity of structural stress computation and fatigue test data transferability, e.g., from lap

Zhang, Lunyu, Wu, Shengjia, Dong, Pingsha

Computational Modeling and Optimization of a Flapping Mechanism Based on the Scotch Yoke Principle

2024-01-2264

04/09/2024

The flight mechanisms of birds have long inspired efforts to develop bioinspired aerial vehicles. This study presents a computational framework to analyze a flapping mechanism's structural behavior and performance based on the Scotch yoke principle. A three-dimensional CAD model is developed and meshed for finite element analysis in ANSYS. Structural steel is chosen as the material. Static analysis is performed under simulated flapping loads to predict deformation, stresses, fatigue life, and failure points. Preliminary results identify regions of high-stress concentration requiring optimization. Topology optimization is conducted to determine an optimal material layout within defined constraints. Additional shape and compliance optimizations are employed. Comparison of initial and optimized designs significantly reduces maximum deformation and stresses throughout the structure. Fatigue life and safety factors are markedly improved. This study enhances understanding of Scotch yoke

Rayed, Ashraf Mahmud, Esakki, Balasubramanian, Banik, Sajal Chandra, Nahin, Ashrafun

Fatigue Life Analysis Methods for Rolling Lobe Air Spring

2024-01-2259

04/09/2024

The fatigue prediction model of an air spring based on the crack initiation method is established in this study. Taking a rolling lobe air spring with an aluminum casing as the studying example, a finite element model for analyzing force versus displacement is developed. The static stiffness and dimensional parameters of limit positions are calculated and analyzed. The influence of different modeling methods of air springs bellow are compared and analyzed. Static stiffness measurement of an air spring is conducted, and the calculation results and the measured results of the static stiffness are compared. It is shown that the relative error of the measured stiffness and calculated stiffness is within 1%. The Abaqus post-processing stage is redeveloped in Python language. The damage parameters including the maximum principal nominal strain, maximum Green-Lagrange strain, and effective stress of air spring bellows are extracted and calculated to find out the critical points, where the

Yu, Yingjin, Yin, Zhihong, Li, Jianxiang, Shangguan, Wen-Bin

A New Equation for Modeling S-N data of Steels

2024-01-2252

04/09/2024

High cycle fatigue (HCF) S-N curves of steels are applied by OEMs for direct evaluation of the products' durability or as an input to their CAE for design purpose. It has been found that the existing models for S-N data resulting HCF test might have difficulties in properly depicting the entire spectrum of fatigue lives. To overcome these difficulties, a new equation has been developed based on the relationship between the behaviors of short and long fatigue lives. The new equation was applied to model S-N data resulting from recent HCF testing of several steels and was compared with the 3 existing popular models. The comparison in the preliminary validations indicated that the new equation has high potential for application in more accurate S-N data modeling and fatigue limit prediction

Huang, Gang

Thermomechanical Fatigue Behavior of a Cast Austenitic Stainless Steel

2024-01-2683

04/09/2024

Cast austenitic stainless steels, such as 1.4837Nb, are widely used for turbo housing and exhaust manifolds which are subjected to elevated temperatures. Due to assembly constraints, geometry limitation, and particularly high temperatures, thermomechanical fatigue (TMF) issue is commonly seen in the service of those components. Therefore, it is critical to understand the TMF behavior of the cast steels. In the present study, a series of fatigue tests including isothermal low cycle fatigue tests at elevated temperatures up to 1100°C, in-phase and out-of-phase TMF tests in the temperature ranges 100-800°C and 100-1000°C have been conducted. Both creep and oxidation are active in these conditions, and their contributions to the damage of the steel are discussed

Liu, Yi, Hess, Devin, Wang, Qigui, Coryell, Jason

Lightweight Design Enabled by Innovative CAE Based Development Method Using Topology Optimization

2024-01-2454

04/09/2024

Carbon neutrality has become a significant target. One essential parameter regarding energy consumption and emissions is the mass of vehicles. Lightweight design improves the result of vehicle life cycle assessment (LCA), increases efficiency, and can be a step towards sustainability and CO2 neutrality. Weight reduction through structural optimization is a challenging task. Typical design development procedures have to be overcome. Instead of just a facelift or the creation of a derivative of the predecessor design, completely alternative design creation methods have to be applied. Automated structural optimization is one tool for exploring completely new design approaches. Different methods are available and weight reduction is the focus of topology optimization. This paper describes a fatigue life homogenization method that enables the weight reduction of vehicle parts. The applied CAE process combines fatigue life prediction and topology optimization. An adapted design for a

Kato, Yoshiya, Ishikawa, Satoru, Puchner, Klaus, Schossleitner, Martin, Gaier, Christian

Water Droplet Collison and Erosion on High-Speed Spinning Wheels

03-17-05-0037

04/04/2024

The water droplet erosion (WDE) on high-speed rotating wheels appears in several engineering fields such as wind turbines, stationary steam turbines, fuel cell turbines, and turbochargers. The main reasons for this phenomenon are the high relative velocity difference between the colliding particles and the rotor, as well as the presence of inadequate material structure and surface parameters. One of the latest challenges in this area is the compressor wheels used in turbochargers, which has a speed up to 300,000 rpm and have typically been made of aluminum alloy for decades, to achieve the lowest possible rotor inertia. However, while in the past this component was only encountered with filtered air, nowadays, due to developments in compliance with tightening emission standards, various fluids also collide with the spinning blades, which can cause mechanical damage. One such fluid is the condensed water in the low-pressure exhaust gas recirculation channel (LP-EGR) formulated at cold

Takács, Richárd, Zsoldos, Ibolya, Szentendrei, Dániel

Wheel Hub Cracks of Heavy-Duty Vehicles due to Drum Brake Shoe-Lining Wear, Friction, and Self-Lock

2024-01-5037

03/21/2024

Wheel hubs with drum brakes of heavy-duty vehicles rarely broke, but some suddenly cracked in the 2000s. The cause of damage was said to be a lack of hub strength. However, the case was suspicious because the hubs were produced according to the design guidelines by the JSAE. In the 1990s, brake shoe-lining materials were changed from asbestos to non-asbestos for people’s health. The brake squeal and abnormal self-lock frequently occurred because of the increased friction coefficient between drum and shoe lining in the case of the leading–trailing type. The mechanical friction coefficient changes with the material and the contact angle, which varies with the wear of shoe lining and the drum temperature. In the previous report, the deformation of the wheel hub under the abnormal self-lock was verified by observing the change of hub attitude in model test equipment. In this paper, a causality between the hub crack damage and the abnormal friction increase is clarified by predicting the

Kanairo, Kazunori, Soejima, Mitsuhiro

Amplitude Method for Detecting Debonding in Stack Bond Adhesive

2024-01-5033

03/13/2024

Adhesively bonded joints have been applied in the automotive industry for the past few decades due to their advantages such as higher fatigue resistance, light weight, capability of joining dissimilar materials, good energy absorption, and high torsional stiffness for overall body structure. They also provide an effective seal against noise and vibration at a low cost. There exists the challenge of defining the fatigue characteristics of adhesive joints under cyclic loading conditions, and conventional methods have limitations in detecting the crack initiation of a bonded joint. This study introduces a method of detecting crack initiation by using the frequency method. It is found that stiffness change in the system is highly correlated to change in natural frequencies. By monitoring the change in natural frequencies, the crack initiation can be detected

Huang, Xiaobao, Barber, Gary

Weld Fatigue Damage Assessment of Rail Track Maintenance Equipment: Regulatory Compliance and Practical Insights

05-17-02-0010

03/04/2024

The use of appropriate loads and regulations is of great importance in weld fatigue assessment of rail on-track maintenance equipment and similar vehicles for optimized design. The regulations and available loads, however, are often generalized for several categories, which proves to be overly conservative for some specific categories of machines. EN (European Norm) and AAR (Association of American Railroads) regulations play a pivotal role in determining the applicable loads and acceptance criteria within this study. The availability of track-induced fatigue load data for the cumulative damage approach in track maintenance machines is often limited. Consequently, the FEA-based validation of rail track maintenance equipment often resorts to the infinite life approach rather than cumulative damage approach for track-induced travel loads, resulting in overly conservative designs. The work presented in this article evaluates and compares the weld fatigue damage of track maintenance

Patil, Dipak, Petersen, Michael

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