Calculation of Random Vibration Fatigue Life from Finite Element Model Calculations

1994 ◽  
Author(s):  
Dean M. Ford
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Random Vibration ◽  
Element Model ◽  
Model Calculations ◽  
Vibration Fatigue

Multi-Fidelity Surrogate Model-Assisted Fatigue Analysis of Welded Joints

2020 ◽  
Author(s):  
Lili Zhang ◽  
Tingli Xie ◽  
Jiexiang Hu ◽  
Ping Jiang ◽  
Jasuk Koo ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Surrogate Model ◽  
Element Model ◽  
Leg Length ◽  
Verification Method ◽  
Leave One Out ◽  
The Finite Element Model

Abstract In this study, an additive scaling function based multi-fidelity (ASF-MF) surrogate model is constructed to fast predict fatigue life as well as the stress distribution for the welded single lap joint. The influence of leg length, leg height, the width of the specimen and load in the fatigue test are taken into consideration. In the construction of the MF surrogate model, the finite element model that is calibrated with the experiment is chosen as the high-fidelity (HF) model. While the finite element model that is not calibrated with the experiment is considered as the low-fidelity (LF) model, aiming to capture the trend of the HF model. The Leave-one-out (LOO) verification method is utilized to compare the prediction performance of the ASF-MF surrogate model with that of the single-fidelity Kriging surrogate model. Results show that the ASF-MF surrogate model can better predict the fatigue life as well as the stress distribution.

Detailed Finite Element Modeling of a High Capacity Mooring Steel Wire Rope: Calculation of the Stress Concentration Near the Connection

2020 ◽  
Author(s):  
Michaël Martinez ◽  
Sébastien Montalvo
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Finite Element Model ◽  
Steel Wire ◽  
High Capacity ◽  
Element Model ◽  
Wire Rope ◽  
Contact Forces ◽  
Life Assessment

Abstract The mooring of floating platforms is an important challenge for the offshore industry. It is an important part of the design engineering and, often, a critical point for the fatigue life assessment. A solution that could improve the fatigue life is to directly connect the mooring rope to the platform, without an intermediate chain. However this solution is not widespread and the behavior of a rope near such a connection is little known. The present paper proposes to better understand this behavior, thanks to a detailed finite element model of the rope. The study case is a steel wire rope directly connected to a floating wind turbine. A local finite element model of the rope has been built, where the wires are individually modeled with beam elements. One end of the rope is clamped, simulating the connection, while tension and cyclic bending oscillations are applied to the other end. A localized bending takes place near the connection, leading to stress concentration in the wires. The stress concentration and the local contact forces are calculated for each wire. These data are important entry parameters for a local failure or fatigue analysis. This latter is however not presented here. Despite IFPEN experience in the development of local finite element models of steel wire ropes, it is the first time that such a high capacity rope (MBL = 12 500 kN) is modeled. This is challenging because of the large diameter of the rope and the large number of wires. However this modeling approach is very valuable for such ropes, because the experimental tests are rare and very expensive.

Random Vibration Analysis of a Printed Wiring Board with Electronic Components

1991 ◽  
Vol 34 (1) ◽  
pp. 25-31
Author(s):  
Jack Roberts ◽  
Debra Stillo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Random Vibration ◽  
Element Model ◽  
Printed Wiring Board ◽  
Electronic Components ◽  
Bending Stresses ◽  
Wiring Board ◽  
Element Technique ◽  
The Finite Element Model

A printed wiring board (PWB) with electronic components has been modeled using the finite element technique and compared with the same PWB experimentally tested in a chassis during a 2 hr random vibration test. Accelerometers were attached to the PWB in locations where nodes existed in the finite element model (FEM). The FEM predicted the first natural frequency to within 10 percent of the test results. Due to wedge locks that loosened during the test, the PWB accelerations in the finite element model and the test differed by as much as 40 percent. The ceramic capacitor on the PWB was modeled in detail with leads attached to the PWB to examine bending stresses in the leads. During the 2 hr test there were no failures for those leads with adequate solder joints. A failure did occur, however, on a lead with insufficient solder. A fatigue analysis of the FEM lead bending stresses indicated lead failure if no solder was used, whereas no failures were predicted for properly soldered leads.

Towards Truly Multiscale Simulation of Fatigue Processes in Metallic Structures

2009 ◽  
Author(s):  
John M. Emery ◽  
Jeffrey E. Bozek ◽  
Anthony R. Ingraffea
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Life Prediction ◽  
Element Model ◽  
Multiscale Simulation ◽  
Fatigue Life Prediction ◽  
Length Scale ◽  
Metallic Structures

The fatigue resistance of metallic structures is inherently random due to environmental and boundary conditions, and microstructural geometry, including discontinuities, and material properties. A new methodology for fatigue life prediction is under development to account for these sources of randomness. One essential aspect of the methodology is the ability to perform truly multiscale simulations: simulations that directly link the boundary conditions on the structural length scale to the damage mechanisms of the microstructural length scale. This presentation compares and contrasts two multiscale methods suitable for fatigue life prediction. The first is a brute force method employing the widely-used multipoint constraint technique which couples a finite element model of the microstructure within the finite element model of the structural component. The second is a more subtle, modified multi-grid method which alternates analyses between the two finite element models while representing the evolving microstructural damage. Examples and comparisons are made for several geometries and preliminary validation is achieved with comparison to experimental tests conducted by the Northrop Grumman Corporation on a wing-panel structural geometry.

Design and Fatigue Life Analysis of a Motorcycle Frame

2014 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Giorgio Previati ◽  
Giampiero Mastinu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Experimental Tests ◽  
Element Model ◽  
Fe Model ◽  
Static Test ◽  
Weld Toe ◽  
Fatigue Life Analysis ◽  
Motorcycle Frame

An off-road motorcycle frame has been analyzed and modified to optimize its fatigue life. The fatigue life of the frame is very important to define the service life of the motorcycle. The strain levels on key parts of the frame were collected during experimental tests. It has been possible to locate the areas where the maximum stress level is reached. A finite element (FE) model of the frame has been developed and used for estimating its fatigue life. Static test bench results have been used to validate the FE model. The accuracy of the finite element model is good, the errors are always below 5% with respect to measured data. The mission profile of the motorcycle is dominated by off-road use, with stress levels close to yield point, so a strain-life approach has been applied for estimating the fatigue life of the frame. Particular attention has been paid to the analysis of the welded connections. A shell and a 3D FE model have been combined to simulate the stress histories at the welds. Two reference maneuvers have been considered as loading conditions. The computed stresses have been used to assess the life of the frame according to the notch stress approach (Radaj & Seeger). The method correlates the stress range in a idealized notch, characterized by a fictitious radius in the weld toe or root, to the fatigue life by using a single S-N curve. New technical frame layouts have been proposed and verified by means of the developed finite element model. The considered approach allows to speed up the design process and to reduce the testing phase.

Design Optimization of Compound Cylinders Subjected to Autofrettage and Shrink-Fitting Processes

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Ossama R. Abdelsalam ◽  
Ramin Sedaghati
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Design Optimization ◽  
Element Model ◽  
Pressure Vessels ◽  
Stress Profile ◽  
Shrink Fitting ◽  
Shrink Fit ◽  
Optimal Configurations

The autofrettage and shrink-fit processes are used to increase the load bearing capacity and fatigue life of the pressure vessels under thermomechanical loads. In this paper, a design optimization methodology has been proposed to identify optimal configurations of a two-layer cylinder subjected to different combinations of shrink-fit and autofrettage processes. The objective is to find the optimal thickness of each layer, autofrettage pressure and radial interference for each shrink-fit, and autofrettage combination in order to increase the fatigue life of the compound cylinder by maximizing the beneficial and minimizing the detrimental residual stresses induced by these processes. A finite element model has been developed in ansys environment to accurately evaluate the tangential stress profile through the thickness of the cylinder. The finite element model is then utilized in combination with design of experiment (DOE) and the response surface method (RSM) to develop a smooth response function which can be effectively used in the design optimization formulation. Finally, genetic algorithm (GA) combined with sequential quadratic programming (SQP) has been used to find global optimum configuration for each combination of autofrettage and shrink-fit processes. The residual stress distributions and the mechanical fatigue life based on the ASME code for high pressure vessels have been calculated for the optimal configurations and then compared. It is found that the combination of shrink-fitting of two base layers then performing double autofrettage (exterior autofrettage prior to interior autofrettage) on the whole assembly can provide higher fatigue life time for both inner and outer layers of the cylinder.

scholarly journals Effect of a rigid toroidal inhomogeneity on the elastic properties of a composite

2018 ◽  
Vol 24 (4) ◽  
pp. 1129-1146 ◽  
Author(s):  
Stanislav Krasnitskii ◽  
Anton Trofimov ◽  
Enrico Radi ◽  
Igor Sevestianov
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Finite Element Model ◽  
Elastic Medium ◽  
Elastic Properties ◽  
Element Model ◽  
Uniform Strain ◽  
Model Calculations ◽  
Torus Surface ◽  
Strain Components

An analytical solution is obtained for the problem of an infinite elastic medium containing a rigid toroidal inhomogeneity under remotely applied uniform strain. The traction on the torus surface is determined as a function of torus parameters and strain components applied at infinity. The results are utilized to calculate components of the stiffness contribution tensor of the rigid toroidal inhomogeneity that is required for calculation of the overall elastic properties of a material containing multiple toroidal inhomogeneities. The analytical results are verified by comparison with finite element model calculations.

Instantaneous Dynamic Analysis of the New Stirring Kneader Shaft

2011 ◽  
Vol 221 ◽  
pp. 472-477
Author(s):  
Zhi Min Fan ◽  
Guang Ting Zhou ◽  
Jian Ping Liu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Dynamic Response ◽  
Finite Element Model ◽  
Dynamic Analysis ◽  
Structural Parameters ◽  
Element Model ◽  
Fatigue Analysis ◽  
Exciting Force ◽  
The Finite Element Model

The finite element model of the stirring kneader shaft was built by PRO/E software, which was inserted into ANSYS. Next, the instantaneous dynamic analysis of the new stirring kneader shaft was carried out. The instantaneous dynamic response of stirring shaft about the exciting force of fluid was obtained, which was to optimize the structural parameters of the stirring shaft. The foundation for the next fatigue analysis was laid based on the instantaneous dynamic response; the fatigue life of stirring kneader shaft can be predicted.

The Application of AAR Load Spectrums in the Fatige Assessment for G70 Tank Carbody

2013 ◽  
Vol 690-693 ◽  
pp. 1960-1965 ◽  
Author(s):  
Sheng Qu ◽  
Ping Bo Wu ◽  
Zhuan Hua Liu
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Model ◽  
Dynamic Stress ◽  
Element Model ◽  
Fatigue Analysis ◽  
Static Method ◽  
Analysis Method ◽  
Major Class ◽  
Calculated Stress

G70 Tank car uesd for transportation on liquidsliquids of gas and bulck goods in form of powder,is one of the major class of Chinese railroad freight cars.And the tank car makes about 18% of the toatal amount of freight cars. In this stduy, the carbdoy finite element model of tank car was constructed,and calculated stress of carbody both empty car and fully loaded car,then get the results of key postsitions. According to the AAR load spectrums on the part of the tank car,translated the results into dynamic stress through the quasi-static method. Calculated the damage of carbody with the fatigue analysis method provied in AAR, compared the fatigue life under various comonent.

Structure Design and Mechanical Analysis on a Large Spaceborne Flat Seam Antenna

2014 ◽  
Vol 543-547 ◽  
pp. 291-294
Author(s):  
Wen Jie Fan ◽  
Xiao Peng Li ◽  
Ning Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Random Vibration ◽  
Element Model ◽  
Mechanical Analysis ◽  
Structure Design

Large spaceborne flat seam antennas boom recently. The structure design of the large flat seam antenna is introduced, and finite element model is built. The first frequency of antenna is obtained from modal analysis and it meet the requirement. The results of sine vibration and random vibration shows that strength satisfy the requirement and it has a certain margin.

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