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Tightening Reliability of Bolted Joints in Calibrated Wrench Method (Improvement of Initial Clamping Force Distribution and Optimum Tightening Torque by Elliptical Confidence Limit)

Tokyo Metropolitan Univ-Ken-ichi Manabe, Satoshi Kobayashi
Tokyo Metropolitan Univ.-Soichi Hareyama
  • Technical Paper
  • 2020-01-0218
To be published on 2020-04-14 by SAE International in United States
On tightening bolted joints, the calibrated wrench method is used in manufacturing industries for a large amount of tightening work. It is important to give high initial clamping force in respect of tightening reliability, prevention of self-loosening, the prevention from fatigue breakage, and so on. In this method the clamping force of bolted joints is controlled by grasping the wrench torque. However, since the clamping force is indirectly applied by wrench, it varies greatly in lot of tightening in factory, etc. Therefore, the calibrated wrench method is not so accurate from the viewpoint of clamping force control. It is thought that distribution of this kind is conventionally varied in a rhombus. When tightening torque and clamping force are considered to be two independent random variables, the clamping force is distributed within an elliptical confidence limit. We also show that the distribution of equivalent stress is obtained in an elliptical confidence limit. Considering the permitted limit for working load stress on a bolted joint, elliptical distribution has big margin to yield point than the shape of…
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User Defined FE Based Connector Joints For Plastics

CAEfatigue Ltd-Neil Bishop, Paresh Murthy
Hella GmbH & Co. KGaA-Thomas Thesing, Odo Karger
  • Technical Paper
  • 2020-01-0186
To be published on 2020-04-14 by SAE International in United States
Spot Welds are a category of joints used extensively in automotive structures, normally for metals. The fatigue analysis of such spot welds can be evaluated using (a) the Point 2 Point (P2P) method where a beam or bar is used to connect the 2 surfaces being joined, (b) a more modern approach where the 1D element is replaced with an “equivalent” brick element, or (c) a third approach falls somewhere between where a “spider” and circular ring of elements is used to represent the spot weld. In all three cases there is an assumption that the cross section is circular. For some specialist cases such as plastic connectors (Heat Stakes) a new user defined weld is proposed. This paper will describe the approach which is based on the concept that a user generated tensor line (equivalent to the theoretical Force/Moment to stress algorithms built into the P2P approach) can be used along with special S-N curves create for different Heat Stake shapes.
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Experimental Study on Static and Fatigue Behavior of a Short Glass Fiber Reinforced Polypropylene

FCA US LLC-Mingchao Guo, Congyue Wang, Jian Tao, Johnson Joseph, Ramchandra Bhandarkar
  • Technical Paper
  • 2020-01-0190
To be published on 2020-04-14 by SAE International in United States
One approach of reducing vehicle weight is using composite materials. Fiber reinforced polypropylene is one of the most popular composite materials. To improve accuracy in prediction of durability performance of structures made of this kind of composite material, static and fatigue properties of a 30% fiber reinforced polypropylene have been physically studied. This paper describes details of test coupon design, fabrication and test setup of both quasi static and fatigue tests. In this study, various fiber orientation (0, 20, 90 degrees & knit line), temperature (-40, 23 and 80 degree C), mean stress (R=-1.0, -0.5, -0.2, 0.1 and 0.4) have been considered and the result of the tests discussed.
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Loads Cascading for Full Vehicle Component Design

CAEfatigue Ltd-Neil Bishop
Desktop Engineering Ltd-Andy Woodward
  • Technical Paper
  • 2020-01-0762
To be published on 2020-04-14 by SAE International in United States
Frequency domain methods of analysis are now being used for the evaluation of fatigue for large vehicle systems and these methods offer advantages over equivalent time domain approaches in a number of ways, including analysis efficiency and the usefulness of derived results. One big potential advantage is to be able to do localized sub-component analysis using “cascaded” loads. Such sub-components can be analyzed with refined parameters such as more sophisticated damping. Local parts can also be re-analyzed at a different phase in the design program. This paper will demonstrate the approach and show examples of the method.
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Fatigue life Prediction of HVAC pipe assembly for measured powertrain load by virtual simulation

FCA Engineering India Pvt Ltd-Sathish Kumar Pandi, C Elango, Kameswara rao Appana, Roshan N. Mahadule, DivaKaruni Murali Krishna
  • Technical Paper
  • 2020-01-0188
To be published on 2020-04-14 by SAE International in United States
Structural durability of automotive components is one of the key requirements in design and development of today’s automobiles. Virtual simulations are used to estimate component durability to save the cost and time required to build the components and testing. The objective of this work is to find the service life of automotive HVAC pipe assembly by calculating cumulative fatigue life for operation under actual powertrain load conditions. Modal transient response analysis is performed using MSC-Nastran with the measured powertrain load time history. Strain based fatigue life analysis is carried out in n-code using modal superposition method (MSM). The estimated fatigue life was compared with the physical test results. This paper also explains the root cause of low fatigue life on pipe assembly and provide the solution. Keywords: Durability, HVAC Pipe, Powertrain, Modal Transient, Fatigue Life
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Review and Assessment of Multiaxial Fatigue Limit Models

FCA Canada Inc-shiping zhang
FCA US LLC-Sean McKelvey, Eniyavan Subramanian, Yung-Li Lee
  • Technical Paper
  • 2020-01-0192
To be published on 2020-04-14 by SAE International in United States
The purpose of this paper is to provide a comparison of multiaxial fatigue limit models and their correlation to experimental data. This paper investigates equivalent stress, critical plane and invariant based multiaxial fatigue models. Several methods are investigated here and are compared based on their ability to predict multiaxial fatigue limits from data published in literature. The equivalent stress based LTJ model, with its ability to account for non-proportional loading, provides very accurate predictions of the fatigue limit under multiaxial loading. This accuracy comes from the model constant which is calculated based on multiaxial fatigue data. This is the only model investigated that requires multiaxial fatigue testing to generate the model parameters. All other models rely on uniaxial test results. Of the five stress based critical plane approaches investigated, the model proposed by Susmel and Lazzarin shows the greatest correlation with the multiaxial fatigue limit data. Overall, the invariant based prismatic hull method has the best agreement with the data found in literature. Additionally, a new critical plane model has been proposed. This new model…
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Random Vibration Fatigue Life Assessment of Transmission Control Module (TCM) Bracket Considering the Mean Stress Effect

General Motors-Neeraj Carpenter, Sudeep Yesudas, Michael D. Nienhuis
  • Technical Paper
  • 2020-01-0194
To be published on 2020-04-14 by SAE International in United States
Random loads are experienced by many engineering systems/components such as the housing and the brackets mounted on the chassis of an automobile, wind blowing on the wind turbine blades, Printed Circuit Board (PCB) used in battery electric vehicles, fuel cell stacks mounted on housing of a fuel cell etc. In automotive systems, random load is caused due to unevenness of the road surface. As these loads are varying in nature, it could lead to the fatigue failure of systems experiencing such loads. To ensure structural integrity, they are designed considering random loads and commercially used FE software packages have the capabilities available to evaluate random vibration fatigue. While above mentioned systems undergo random loads during operation, there are other loads/stresses also acting on them such as assembly loads (bolt preload), residual stresses due to casting, static loads i.e. load due to belt or chain drive etc. Consideration of all significant loads are extremely important for a design engineer and CAE analyst while designing such systems in order to ensure the reliability of their design. The…
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EDGE-QUALITY EFFECTS ON MECHANICAL PROPERTIES OF STAMPED NON-ORIENTED ELECTRICAL STEEL

GM Powertrain-Peggy Jones
General Motors-Margarita Thompson, Paul Crepeau
  • Technical Paper
  • 2020-01-1072
To be published on 2020-04-14 by SAE International in United States
The market for electric vehicles and hybrid electric vehicles is expected to grow in the coming years, which is increasing interest in design optimization of electric motors for automotive applications. Under demanding duty cycles, the moving part within a motor, the rotor, may experience varying stresses induced by centrifugal force, a necessary condition for fatigue. Rotors contain hundreds of electrical steel laminations produced by stamping, which creates a characteristic edge structure comprising rollover, shear and tear zones, plus a burr. Fatigue properties are commonly reported with specimens having polished edges. Since surface condition is known to affect fatigue strength, an experiment was conducted to determine the effect of sample preparation in stamped specimens. Tensile properties were unaffected by polishing. In contrast, polishing was shown to increase fatigue strength by approximately 10-20% in the range of 105-107 cycles to failure.
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Frame structure durability development methodology for various design phases

FCA Engineereing India Pvt Ltd-Venkatesh Naik
FCA Engineering India Pvt Ltd-RAGHAVENDRA BYALI
  • Technical Paper
  • 2020-01-0196
To be published on 2020-04-14 by SAE International in United States
It is a challenging task to find an optimal design concept for a truck frame structure given the complexity of loading conditions, vehicle configurations, packaging and other requirements. In addition, there is a great emphasis on light weight frame design to meet stringent emission standards. This paper provides a framework for fast and efficient development of a frame structure through various design phases, keeping durability in perspective while utilizing various weight reduction techniques. In this approach frame weight and stiffness are optimized to meet strength and durability performance requirements. Fast evaluation of different frame configurations during the concept phase (I) was made possible by using DFSS (Design For Six Sigma) based system synthesis techniques. This resulted in a very efficient frame ladder concept selection process. Frame gauge optimization during the subsequent development phase (II) utilizing a newly developed damage based approach greatly reduced the number of design iterations relative to a typical stress based approach. In the light weighting phase(III) that followed, a method was established to effectively locate and optimize lightening holes using fatigue…
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Experimental-numerical correlation of a multi-body model for comfort analysis of an heavy truck

CNH Industrial-Enrica Capitelli, Andrea Morello, Vladi Nosenzo
Politecnico di Torino-Enrico Galvagno, Michele Galfrè, Mauro Velardocchia
  • Technical Paper
  • 2020-01-0768
To be published on 2020-04-14 by SAE International in United States
In automotive market, today more than in the past, it is very important to reduce time to market and, mostly, developing costs before the final production start. Ideally, bench and the on-road tests can be replaced by multi-body studies because virtual approach guarantees test conditions very close to reality and it is able to exactly replicate the standard procedures. Approval authorities are starting to look at simulations to release homologation certificates. Therefore, today, it is essential to create very reliable models, able to forecast the vehicle behavior on every road condition (including uneven surfaces). The aim of this study is to build a reliable multi-body model of a heavy commercial vehicle and to correlate experimental and numerical data related to comfort analysis for validation purposes. Experimental results are recorded during tests carried out at different speeds and loading conditions on a Belgian blocks track. Simulation data are obtained reproducing the on-road test conditions in multi-body environment. The virtual vehicle is characterized by rigid and flexible bodies, the tire model used is FTire (Flexible Structure Tire…