Automotive Body Fatigue Analysis – Inertia Relief or Transient Dynamics?

Anvari, Majid; Beigi, Babak

doi:10.4271/1999-01-3149

“…The main idea is to counteract the unbalanced applied loads by a set of rigid body accelerations, the latter providing body forces which are distributed over the structure in such a way that the applied forces are equilibrated and the static analysis can be performed. The technique is available into most of the commercial finite element (FE) packages and it has been widely used by the industry in different fields 2‐10 …”

Section: Introductionmentioning

confidence: 99%

“…The technique is available into most of the commercial finite element (FE) packages and it has been widely used by the industry in different fields. [2][3][4][5][6][7][8][9][10] The static global stiffness analysis of a body in white (BIW) is a common example that involves the computational simulation of an unconstrained configuration using the IR method. The BIW global stiffness plays a significant role in the design process of a car.…”

mentioning

confidence: 99%

Nonintrusive reduced order model for parametric solutions of inertia relief problems

Cavaliere

¹

,

Zlotnik

²

,

Sevilla

³

et al. 2021

Numerical Meth Engineering

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The Inertia Relief (IR) technique is widely used by industry and produces equilibrated loads allowing to analyze unconstrained systems without resorting to the more expensive full dynamic analysis. The main goal of this work is to develop a computational framework for the solution of unconstrained parametric structural problems with IR and the Proper Generalized Decomposition (PGD) method. First, the IR method is formulated in a parametric setting for both material and geometric parameters. A reduced order model using the encapsulated PGD suite is then developed to solve the parametric IR problem, circumventing the so-called curse of dimensionality. With just one offline computation, the proposed PGD-IR scheme provides a computational vademecum that contains all the possible solutions for a predefined range of the parameters. The proposed approach is nonintrusive and it is therefore possible to be integrated with commercial finite element (FE) packages. The applicability and potential of the developed technique is shown using a three-dimensional test case and a more complex industrial test case. The first example is used to highlight the numerical properties of the scheme, whereas the second example demonstrates the potential in a more complex setting and it shows the possibility to integrate the proposed framework within a commercial FE package. In addition, the last example shows the possibility to use the generalized solution in a multi-objective optimization setting. K E Y W O R D Sinertia relief, nonintrusive, proper generalized decomposition, reduced order model, shape optimization INTRODUCTIONUnconstrained structures are widespread in the automotive, aerospace and naval industry. As is well known, due to the singularity of the stiffness matrix, conventional static analyses cannot be performed if the system undergoes rigid body motions. At the same time, imposing dummy constraints in order to make a free-body system statically determinate leadsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…In addition, there were other hybrid methods which utilized both static and dynamic analyses simultaneously [17,18]. Based on the results published in a previous research by Anvari and Beigi [19], the use of quasi-static method for the stress analysis of the BIW is only allowed if the loading frequency is less than 10% of the first nonzero natural frequency of the structure. Although the loading applied in their research was fully reversed sinusoidal force at a specific node (not a real loading condition), it gave a good understanding that how much difference inertia effects can make in the results.…”

Section: Introductionmentioning

confidence: 99%

A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses

Farrahi

¹

,

Ahmadi

²

,

Kashyzadeh

³

et al. 2020

Frattura Ed Integrità Strutturale

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Owing to the expensive and time-consuming nature of durability experiments, finite element based durability analysis is quite prevalent in the automotive industry. Numerical fatigue life analyses are typically divided into two different categories, the quasi-static methods which are faster and the dynamic methods which are more accurate. The aim of this paper is to compare the inertia relief and modal dynamic approaches in terms of formulation, accuracy and computation time. The chosen case study is the fatigue life of the vehicle body which is considered the main load-bearing component in a vehicle. By utilizing multi-body dynamics model and driving the vehicle on different standardized roads and by different velocities, the loadings, which act on the body are calculated and later used for the stress analysis. Then, by using the structural stress method, the fatigue life of the vehicle spot welds is calculated and the results are compared for both approaches. The findings reveal that the modal dynamic method is almost 37 times more time-consuming than the inertia relief approach, but if accuracy is desired, it can be up to 96% more accurate. Also

show abstract

“…The main idea is to counteract the unbalanced applied loads by a set of rigid body accelerations, the latter providing body forces which are distributed over the structure in such a way that the applied forces are equilibrated and the static analysis can be performed. The technique is available into most of the commercial finite element packages and it has been widely used by the industry in different fields [2,3,4,5,6,7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Nonintrusive reduced order model for parametric solutions of inertia relief problems

Cavaliere

¹

,

Zlotnik

²

,

Sevilla

³

et al. 2020

Preprint

0

View full text Add to dashboard Cite

The Inertia Relief (IR) technique is widely used by industry and produces equilibrated loads allowing to analyze unconstrained systems without resorting to the more expensive full dynamic analysis. The main goal of this work is to develop a computational framework for the solution of unconstrained parametric structural problems with IR and the Proper Generalized Decomposition (PGD) method. First, the IR method is formulated in a parametric setting for both material and geometric parameters. A reduced order model using the encapsulated PGD suite is then developed to solve the parametric IR problem, circumventing the so-called curse of dimensionality. With just one offline computation, the proposed PGD-IR scheme provides a computational vademecum that contains all the possible solutions for a pre-defined range of the parameters. The proposed approach is nonintrusive and it is therefore possible to be integrated with commercial FE packages. The applicability and potential of the developed technique is shown using a three dimensional test case and a more complex industrial test case. The first example is used to highlight the numerical properties of the scheme, whereas the second example demonstrates the potential in a more complex setting and it shows the possibility to integrate the proposed framework within a commercial FE package. In addition, the last example shows the possibility to use the generalized solution in a multi-objective optimization setting.

show abstract

Automotive Body Fatigue Analysis – Inertia Relief or Transient Dynamics?

Cited by 14 publications

References 3 publications

Nonintrusive reduced order model for parametric solutions of inertia relief problems

Nonintrusive reduced order model for parametric solutions of inertia relief problems

A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses

Nonintrusive reduced order model for parametric solutions of inertia relief problems

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