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Viewing 1 to 30 of 15341
2011-04-12
Technical Paper
2011-01-0438
Ahmet Kanbolat, Murathan Soner, Tolga Erdogus, Mustafa Karaagac
The parabolic leaf spring plays a vital role in suspension systems, since it has an effect on ride comfort and vehicle dynamics. Primarily, leaf spring endurance must be ensured. Presently, there are two approaches to designing a leaf spring. In the traditional method, fatigue tests should be repeated for each case, considering different material, geometry and suspension hard points. However, it takes a long time and requires a heavy budget to get the optimized solution. In the contemporary method, a numerical approach is used to obtain the fatigue life and the leaf geometry against the environmental condition on the basis of material properties. This paper presents a more precise method based on non-linear finite element solutions by evaluating the effects of the production parameters, the geometrical tolerances and the variations in the characteristics of the material.
2011-04-12
Technical Paper
2011-01-0399
Andre Ferrarese, Jason Bieneman, David J. Domanchuk, Thomas Smith, Thomas Stong, Peter Einberger
Changing emission legislation limits are challenging the engine developers in many aspects. Requirement to improve combustion and engine efficiency have resulted in increased loads and higher levels of abrasive particles within the engine environment. Concerning piston rings and piston ring grooves, such engine modifications are leading to critical tribological conditions and side wear is becoming a key issue in the design of these components. Historically one of the most common forms of side wear protection on piston rings has been chromium plate. This solution has limitations on durability (low thickness) and on topography (rough surfaces). In response to these limitations, nitrided stainless steel top rings have been used to improve the side protection; it is harder and typically has a smoother surface finish when compared to chromium coating.
2011-04-12
Journal Article
2011-01-0470
Pai-Chen Lin, Ru-Yi He, Zheng-Ming Su, Zhi-Long Lin
Failure modes of spot friction welds in cross-tension specimens of aluminum 6061-T6 sheets are first investigated based on experimental observations. Optical and scanning electron micrographs of the welds before and after failure under quasi-static and cyclic loading conditions are examined. Experimental results show that the failure modes of the welds under quasi-static and cyclic loading conditions are quite different. Under quasi-static loading conditions, the failure mainly starts from the necking of the upper sheet outside the weld. Under low-cycle loading conditions, the dominant fatigue cracks are the kinked cracks growing into the upper sheet from the crack tips; hence, the upper nugget pullout failure mode can be seen. Under high-cycle loading conditions, the dominant fatigue cracks are kinked cracks growing into the lower sheet from the crack tips; subsequently, the lower nugget pullout failure mode can be seen.
2011-04-12
Technical Paper
2011-01-0669
Azadeh Sheidaei, Xinran (Sharon) Xiao, Xiaosong Huang, Jixin Wang
The mechanical behavior of a commercially available single layer polypropylene (PP) separator was investigated using a dynamic mechanical analyzer (DMA). Samples were tested along the machine direction (MD) and transverse direction (TD). The tensile stress-strain, tensile creep and viscoelastic behaviors were studied. Experiments were performed in two conditions: (1) dry and (2) wet, i.e., samples submersed in dimethyl carbonate (DMC). The experimental results revealed that the mechanical properties of the separator were much lower while being submersed in DMC. This finding suggests that the mechanical properties measured at a dry condition may not be sufficient to represent the in-situ material behavior. Therefore, it is important to conduct material characterization in an environment close to the service condition.
2011-04-12
Technical Paper
2011-01-0015
Brian P. Hake
Delivering the appropriate material data for CAE analysis of plastic components is not as straight forward as it would seem to be. While a few of the properties typically used by resin manufacturers and material engineers to describe a plastic are useful to the analysis community (density, CLTE), most are not (flexural modulus, notched izod). In addition some properties such as yield stress are defined differently by the analysis community than by the materials community. Lastly, secondary operations such as painting or chrome plating significantly change the behavior of components with plastic substrates. The materials engineering community and the CAE analysis community must work together closely to develop the material data necessary to increase the capability of the analysis. This paper will examine case studies where these issues have required modifications to the material property data to increase the fidelity of the CAE analysis.
2011-04-12
Technical Paper
2011-01-0223
Joel Hemanth
This paper describes research on aluminum-based metal matrix hybrid composites reinforced with kaolinite (Al₂SiO₅) and carbon (C) particulates cast using high rate heat transfer technique during solidification by employing metallic, non-metallic and cryogenic end chills. The effect of reinforcement and chilling on strength, hardness and wear behavior are discussed in this paper. It is discovered that cryogenic chilled MMCs with Al₂SiO₅-9 vol. %/C-3 vol. % dispersoid content proved to be the best in enhancing the mechanical and wear properties. A physically based finite element (FE) model for the abrasive wear of the hybrid composite developed is based on the mechanisms associated with sliding wear of ductile aluminum matrix of the composite containing hard Al₂SiO₅ and soft carbon (dry lubricant) reinforcement particles.
2011-04-12
Technical Paper
2011-01-0199
Thomas Christiner, Wilfried Eichlseder, Istvan Gódor, Johannes Reiser, Franz Trieb, René Stuehlinger
Recent trends in mechanical engineering are focusing on optimization of components with respect both to weight and lifetime by using numerical simulation even in the early design stages. For a reliable prediction of in service performance by simulation, both loading as well as different damage and failure mechanisms that may be activated during operation have to be known. In mechanical engineering applications, cyclic loadings are most common. In many assemblies of moving components, contact problems under various lubrication conditions are lifetime-limiting. There, relative motion of contacting bodies combined with high loads transmitted via the contact surface lead to fretting fatigue failure. In this contribution a few selected results of a currently conducted research project are presented. The aim of this study was to examine the material behavior of a surface stressed steel. The influence of the Fretting regime on fatigue properties has been investigated.
2011-04-12
Technical Paper
2011-01-0198
Masahiro Fujimoto, Atsushi Fujii, Nobuyuki Matsumiya
Since wear resistance and fatigue strength are key requirements for chassis components, induction hardening is widely used to apply compressive stress for controlling crack growth. Therefore, it is crucial that the influence of defects is examined with compressive residual stress applied to parts. In this report, the relationship between crack depth and compressive residual stress is evaluated using a cylindrical specimen and a torsional fatigue test. The test results were found to be consistent with CAE simulations performed in advance. In the future, it will be necessary to make this method applicable to product design to further improve vehicle safety performance.
2011-04-12
Journal Article
2011-01-0196
Hong Tae Kang, Abolhassan Khosrovaneh, Todd Link, John Bonnen, Mark Amaya, Hua-Chu Shih
Gas Metal Arc Welding (GMAW) is widely employed for joining relatively thick sheet steels in automotive body-in-white structures and frames. The GMAW process is very flexible for various joint geometries and has relatively high welding speed. However, fatigue failures can occur at welded joints subjected to various types of loads. Thus, vehicle design engineers need to understand the fatigue characteristics of welded joints produced by GMAW. Currently, automotive structures employ various advanced high strength steels (AHSS) such as dual-phase (DP) and transformation-induced plasticity (TRIP) steels to produce lighter vehicle structures with improved safety performance and fuel economy, and reduced harmful emissions. Relatively thick gages of AHSS are commonly joined to conventional high strength steels and/or mild steels using GMAW in current body-in-white structures and frames.
2011-04-12
Journal Article
2011-01-0193
Qigui Wang, Peggy Jones
Cast aluminum alloys are increasingly used in cyclically loaded automotive structural applications for light weight and fuel economy. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the absence of casting flaws, however, crack initiation occurs at the fatigue-sensitive microstructural constituents. Cracking and debonding of large silicon (Si) and Fe-rich intermetallic particles and crystallographic shearing from persistent slip bands in the aluminum matrix play an important role in crack initiation. This paper presents fatigue life models for aluminum castings free of casting flaws, which complement the fatigue life models for aluminum castings containing casting flaws published in [1].
2011-04-12
Journal Article
2011-01-0101
Akshay Narasimhan, John Ziegert, Lonny Thompson
The Michelin Tweel tire structure has recently been developed as an innovative non-pneumatic tire which has potential for improved handling, grip, comfort, low energy loss when impacting obstacles and reduced rolling resistance when compared to a traditional pneumatic tire. One of the potential sources of vibration during rolling of a non-pneumatic tire is the buckling phenomenon and snapping back of the spokes in tension when they enter and exit the contact zone. Another source of noise was hypothesized due to a flower petal ring vibration effect due to discrete spoke interaction with the ring and contact with the ground during rolling as the spokes cycle between tension and compression. Transmission of vibration between the ground force, ring and spokes to the hub was also considered to be a significant contributor to vibration and noise characteristics of the Tweel.
2011-04-12
Journal Article
2011-01-0475
Teresa J. Franklin, Jwo Pan, Michael Santella, Tsung-Yu Pan
Fatigue behavior of dissimilar ultrasonic spot welds in lap-shear specimens of magnesium AZ31B-H24 and hot-dipped-galvanized mild steel sheets is investigated based on experimental observations, closed-form stress intensity factor solutions, and a fatigue life estimation model. Fatigue tests were conducted under different load ranges with two load ratios of 0.1 and 0.2. Optical micrographs of the welds after the tests were examined to understand the failure modes of the welds. The micrographs show that the welds mainly fail from kinked fatigue cracks growing through the magnesium sheets. The optical micrographs also indicate that failure mode changes from the partial nugget pullout mode under low-cycle loading conditions to the transverse crack growth mode under high-cycle loading conditions. The closed-form stress intensity factor solutions at the critical locations of the welds are used to explain the locations of fatigue crack initiation and growth.
2011-04-12
Journal Article
2011-01-0473
Kamran Asim, Kulthida Sripichai, Jwo Pan
In this paper, the fatigue behavior of laser welds in lap-shear specimens of non-galvanized SAE J2340 300Y high strength low alloy (HSLA) steel sheets is investigated based on experimental observations and a fatigue life estimation model. Optical micrographs of the laser welds before and after failure under quasi static and cyclic loading conditions are examined. The micrographs show that the failure modes of laser welds under quasi-static and cyclic loading conditions are quite different. Under quasi-static loading conditions, the weld failure appears to be initiated from the base metal near the boundary of the base metal and the heat affected zone at a distance to the pre-existing crack tip, and the specimens fail due to the necking/shear of the lower left load carrying sheets.
2011-04-12
Technical Paper
2011-01-0480
Dongchoul Kim, Quhon Han, Sungjun Gong, HeeJin Kang, Chun Woo Shin, Tae Soo Lee
Fatigue is the most critical failure mode of spot-welded joints in automobiles. Although various approaches have been proposed for fatigue life estimation of spot welds, a practical tool for spot welds in a fully built vehicle has not been thoroughly established. Since the spot welds in the assembled vehicle generally are situated in complex geometries under multi-axial loading, the most effective tool for fatigue life estimation might be the direct strain measurement. Here, a practical and reliable technique for fatigue life prediction of spot-welds based on direct strain measurement is proposed. The developed technique shows that the fatigue life of spot welds can be estimated by a multiple strain-gauge pattern attached to the outer surface of the overlap sheets near the spot weld. The designed pattern measures strain signals from circumferentially aligned strain gauges, which effectively provide information for fatigue life prediction after a simple conversion process.
2011-04-12
Journal Article
2011-01-0485
Marko Nagode, Michael Hack
In the last decades the development time of vehicles has been drastically reduced due to the application of advanced numerical and experimental methods. Specifications concerning durability and other functional attributes for every new model improve for every vehicle. In particular, for machines and components under variable multiaxial loading, fatigue evaluation is one of the most important steps in the design process. Appropriate material testing and simulation is the key to efficient life prediction. However, the life of automotive components, power plants and other high-temperature facilities depends mostly on thermo-mechanical fatigue (TMF). This is due to the normally variable service conditions, which contain the phases of startup, full load, partial load and shut-down.
2011-04-12
Journal Article
2011-01-0483
Sangwoo Cha, Hoon Chang, Kyung-Woo Lee, Sung-san Cho, Dong-hyeon Hwang
Periodically, engine block-bearing cap structure is subject to the mixed bearing load from combustion and inertia mass of crank. Recently, due to the trend of lightness, cast steel is replaced with aluminum in the material of gasoline engine block. And, the load acting on the main bearing cap is rapidly rising due to the increase of engine power. Therefore, in the development stage, fretting fatigue failures frequently occurred on the block face contacted with the bearing cap. Fretting is a kind of wear which is occurred by micro relative movement. Even though various researches have been made to investigate fretting fatigue failure with FEA approaches, they are not enough to evaluate the phenomenon. In this study, the new CAE method simulating the fretting fatigue failure on the engine block face is developed and the mechanism of the fretting fatigue on the engine block is investigated.
2011-04-12
Journal Article
2011-01-0487
Nima Shamsaei, Ali Fatemi
A procedure for fatigue life estimation of components and structures under variable amplitude multiaxial loadings based on simple and commonly available material properties is presented. Different aspects of the analysis consisting of load cycle counting method, plasticity model, fatigue damage parameter, and cumulative damage rule are presented. The only needed material properties for the proposed procedure are hardness and monotonic and axial cyclic deformation properties (HB, K, n, K′ and n′). Rainflow cycle counting method is used for identifying number of cycles. Non-proportional cyclic hardening is estimated from monotonic and axial cyclic deformation behaviors. A critical plane approach is used to quantify fatigue damage under variable amplitude multiaxial loading, where only material hardness is used to estimate the fatigue curve, and where the needed deformation response is estimated based on Tanaka's non-proportionality parameter.
2011-04-12
Journal Article
2011-01-0489
Jaewon Lee, Jwo Pan, Yung-Li Lee, Simon Ho
Effects of roller diameter and number on the contact pressures, subsurface stresses and the fatigue lives of cam roller follower bearings are investigated in this paper. Finite element analyses under plane strain conditions were conducted to identify the effects of the diameter and number of the rolling elements and the thickness of the outer ring. The fatigue life of the inner pin generally increases as the roller diameter increases. But, reducing the number of rollers to accommodate larger rollers does not necessarily increase the fatigue life. The inevitable decrease of the thickness of the outer ring due to the increase of the roller diameter results in the increase of compliance for the outer ring. This increase of compliance leads to excessive deformation of the outer ring and consequently more load must be carried by fewer number of rolling elements.
2011-04-12
Journal Article
2011-01-0488
Sean Mckelvey, Ali Fatemi
Fatigue fractures are the most common type of mechanical failures of components and structures. It is widely recognized that surface finish has a significant effect on fatigue behavior. Forgings can be accompanied by significant surface roughness and decarburization. The correction factors used in many mechanical design textbooks to correct for the as-forged surface condition are typically based on data published in the 1940's. It has been found by several investigators that the existing data for as-forged surface condition is too conservative. Such conservative values often result in over-engineered designs of many forged parts, leading not only to increased cost, but also inefficiencies associated with increased weight, such as increased fuel consumption in the automotive industry. In addition, this can reduce forging competitiveness as a manufacturing process in terms of cost and performance prediction in the early design stage, compared to alternative manufacturing processes.
2011-04-12
Journal Article
2011-01-0609
Takahiro Sano, Takeyuki Nakasone, Takeshi Katagiri, Yutaka Okamoto
Recently, automotive engines have been operating under harsh conditions of high-power, low viscosity oil and increase of start-stop (e.g. idling stop). In plain bearing used within engine, as oil film thickness decreases, the frequency of direct contacts on the sliding surfaces between the shaft and the bearing are gradually increasing. In fact, the plain bearings for engines would tend to be used under mixed lubrication and the contacts of the surface roughness asperities sometimes occur between the shaft and the bearing. As a result, the bearing wear on the sliding surfaces is accelerated by the contacts of the roughness asperities. In order to predict the bearing performance exactly, it is very important to understand the change progress of the geometric shape of sliding surfaces caused by the wear.
2013-04-08
Technical Paper
2013-01-1391
Mrunal R. Hatwalne, Prachi Joshi
Automotive Industry is constantly upgrading the value offered on their products at optimized cost. Scratch and mar resistance of interiors and exterior parts, is an important attribute which is linked to perceived quality and value offered to customers. Polypropylene material is optimum material of choice for these parts due to its unique advantages. However, filled polypropylene material has poor scratch and mar resistance. Many techniques for scratch resistance improvement are available such as additions of slip agents, co additives, special fillers, siloxanes, etc. However, some of them may offer some disadvantages like stickiness or tackiness on the surfaces. The choice depends on its effectiveness & cost. This paper deals with design of experiments to evaluate effectiveness of 4 types of additives and their optimum % to give scratch resistance improvement without having detrimental impact on other critical properties.
2013-04-08
Journal Article
2013-01-1166
Cliff Butcher, David Anderson, Michael Worswick
Hole expansion of a dual phase steel, DP600, was numerically investigated using a damage-based constitutive law to predict failure. The parameters governing void nucleation and coalescence were identified from an extensive review of the x-ray micro-tomography data available in the literature to ensure physically-sound predictions of damage evolution. A recently proposed technique to experimentally quantify work-hardening and damage in the shear-affected zone is incorporated into the damage model to enable fracture predictions of holes with sheared edges. Finite-element simulations of a hole expansion test with a conical punch were performed for both a punched and milled hole edge condition and the predicted hole expansion ratios are in very good agreement with the experiment values reported by several researchers.
2013-04-08
Journal Article
2013-01-1168
Osamu Sonobe, Yuji Hashimoto, Jiro Hiramoto, Toru Inazumi
For the newly developed tube bending method termed “PRB,” finite element analyses (FEA) with solid elements were carried out to clarify the tube deformation mechanism in comparison with that in conventional rotary draw bending. The following results were obtained. 1 In the investigation of the strain and stress states both outside and inside the bend, it was found that plastic deformation in PRB was almost completed before the tube material entered the bend area. In rotary draw bending, plastic deformation developed in the bend area.2 Regarding the effect of tube reduction in diameter by the pressure die in deformation of tubes, circumferential compressive deformation involving longitudinal tensile deformation is enhanced outside the bend.
2013-04-08
Technical Paper
2013-01-1171
Praveen Balaj Balakrishnan, Sathya Dev, Deepak Bhuyan, Parvez Syed, Sarin Babu Thokala
Automotive industry's migration to usage of HSS (High Strength Steels), AHSS (Advance High Strength Steels) from conventional steels for their low weight and high strength properties has had its significant effects on die wear. The unpredictability of die wear can pose manufacturing issues, for example, undesirable tool life. Hence die wear has been gaining immense attention and lot of research work has been carried out to provide a die wear prediction method. This paper focuses on the method of estimating wear mathematically based on the mechanics behind die wear phenomenon. This is also an effort to study wear on die for an automotive component in critical areas for which the amount of wear are calculated. This study is further to be correlated with production data from die maintenance record, explicit measurement of die wear, etc., to validate the estimation.
2013-04-08
Technical Paper
2013-01-1221
Ilyas Istif, Ovun Isin, Erdem Uzunsoy, Deniz Uzunsoy
Prediction of brake disc materials wear versus their formulation with brake operating conditions can play a critical role in the development of future brake disc materials. In this paper identification of the dry sliding wear behavior of magnesium (Mg) matrix (MMCs) reinforced with 0-3-6 wt % B4C particulates (B4Cp) was investigated. Wear tests were performed on a pin-on-disk configuration against SAE 1040 steel counter body under constant load and sliding speed. The wear resistance of composites was evaluated as a function of B4C particulates reinforcement. Identified models were based on experimental results. The wear load was considered as the input parameter, whereas the wear rate and friction of coefficient as the output parameter. A first order continuous-time linear model structure was chosen for the modeling. Simulations using the identified models were compared with experimental results and it was found that the modeling of wear process was satisfactory.
2013-04-08
Journal Article
2013-01-1218
Saikrishna Sundararaman
One of the commonly used methods for evaluating friction and wear behavior of hard plastics is described in ASTM 3702 test specification. Wear tests conducted using this test method show that friction coefficient is dependent on temperature (generated due to friction), especially for filled plastics. Tests with high load and / or speed result in melting of the plastic due to excessive temperature build up. In the present study, a method has been developed to conduct dry and lubricated wear tests while controlling test temperature. Controlling temperature ensures that the failure mode of the test specimen is due to wear and not due to melting resulting from excessive temperature build up. The details of temperature control for both dry and lubricated wear tests are outlined and wear rate / friction for different combinations of loads and speeds are presented.
2013-04-08
Journal Article
2013-01-1219
Ionut C. Harta, Kayla Owens, Steven De Jesús Santiago, David Schall, Steven Thrush, Gary Barber, Qian Zou
The tribological performance of nanofluids consisting of ZnO nanoparticles dispersed with a stabilizer in an API Group III oil was investigated. Recent research suggests that these fluids may reduce friction and wear compared to the base oil when used as a lubricant in metal-on-metal tests. The effects of nanoparticle concentration and test temperature on friction and wear were studied. Tests were run at 50°C and 100°C to investigate the viability of the fluids at elevated temperatures because possible applications include use as engine lubricants. Nanofluids showed friction reduction of up to 5.2% and reduced wear by up to 82.8% versus oil with only stabilizer at the highest ZnO concentration and the lowest temperature. Stabilizer increased wear at every concentration, but did not affect friction significantly. Fluid viscosity was also investigated. At 30°C, significant shear-thinning behavior was observed for the 2% ZnO solution, and a viscosity versus shear rate curve was found.
2013-04-08
Technical Paper
2013-01-1216
Ovun Isin, Ilyas Istif, Erdem Uzunsoy, Deniz Uzunsoy
The brake friction materials in an automotive brake system play important role in the overall braking performance of a vehicle. A previous study by the same authors was focused on wear testing for a 1040 steel disc interacting with Powder metallurgy (PM) copper-based brake lining material with and without MoS₂ additive at constant applied load and sliding velocity. In this paper, a non-Linear Autoregressive model (ARX) Model structure with sigmoid network having one hidden layer and nonlinear ANFIS (Adaptive Neuro-Fuzzy Inference System) model structure was used to find the best possible wear prediction results and both approaches have been applied to simulate wear behavior of the brake lining material. Preliminary results showed that ARX provides closer results to the experiments than the ANFIS model. As a result, nonlinear ARX modeling can be used as an effective tool in the prediction of brake lining material properties instead of time-consuming experimental processes.
2013-04-08
Technical Paper
2013-01-1176
Roman Hillermeier, Tareq Hasson, Lars Friedrich, Cedric Ball
Composite materials have gained the attention of the automotive industry to substantially reduce vehicle weight, reduce CO₂ emissions and improve the fuel economy of next generation vehicles. Thermosetting matrix technology combined with glass or carbon fiber reinforcements are well suited for structural applications where mostly steel and aluminum are used today. However, the lack of fast production techniques and fast reacting matrix technologies have limited composites use to low volume production models. A new generation of epoxy resin systems has been developed that allows the rapid processing of structural composites for medium to high volume models. These advanced formulations maintain the excellent properties of traditional epoxy-based composites, yet the tested systems can process in a matter of minutes using modern manufacturing technologies such as the high pressure resin transfer molding (HP-RTM) process.
2013-04-08
Journal Article
2013-01-1174
Tejas Chaukulkar, Prajeen Dumbare, Rahul Waikar
LM-13 aluminum alloys reinforced with B₄C particles (5, 10, 15 wt. %) were prepared by gravity die casting. The samples were characterized on the basis of microstructure, microhardness, XRD and SEM. The microhardness tests indicated increased hardness values of the metal matrix composite (MMC) as B₄C percentage increased. Optical microscopic observation revealed presence of rhomboidal hard B₄C particles distributed randomly in the LM-13 matrix. Presence of B₄C was also confirmed with XRD Analysis. The dry sliding wear behavior of this LM-13 - B₄C composite was investigated by means of the pin-on-disc technique. The results showed that as the B₄C % increased, the volumetric wear decreased proportionately - indicating the active role of the B₄C particles in wear reduction. Study of the worn surfaces of the composite using the SEM suggests presence of adhesive and abrasive wear mechanisms with evidence of transfer films.
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