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Frequency Domain Fatigue Analysis of Exhaust Systems
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 03, 2018 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Today in the automotive industry, there is a continual reduction in available development time. There is also an urgent need to reduce cost and weight, to adapt to customer and legislation which drives to an increase in design complexity. These challenges are sometimes made harder by the late availability of hardware and this creates the need to extend and continually improve the established CAE methods which are used to develop automotive parts. This holds especially true in the field of exhaust systems and their components, which experience loads from various sources like temperature, engine or road.
In the field of road excitation the use of dynamic transient simulation and subsequent damage calculation is state of the art in terms of simulations methodology. Nevertheless the problems of this method are the long calculation times and large scratch data requirements as well as the necessary precise knowledge of the test track profile, which is generally not available in early project phases or sometimes cannot be communicated by the OEM to suppliers. This lack of information results, in many cases, in the usage of simplistic, experience based static approaches that do not display the real dynamic behaviour and lead to over engineering.
Frequency domain methods for fatigue analysis and/or for general random response analysis have experienced resurgence over the last years due to improved technology and better computational processes. In previous papers, frequency based fatigue methods have been successfully applied displaying good correlation with the time based approach. This paper will propose a possible alternative to the use of the transient method or other, simplified static approaches for the development of complete passenger car exhaust systems using the capabilities of a frequency based fatigue method in a realistic scenario, i.e. under multi-position and multi-directional excitation.
The key steps of such a frequency domain analysis will be discussed in the following. The first step relates to the conversion of the multi-channel load time histories followed by the second step related to how boundary conditions are placed. Then, the frequency domain results are compared in detail with traditional time based results. At the end of the comparison, a detailed overview of the calculation time and disk space needed for both methods will be shown in order to demonstrate the real advantage in the use of the frequency base fatigue method.
As a conclusion and outlook, the huge opportunities to improve the cooperation between OEM and suppliers without compromising any precise information about track profiles using the power spectral density PSD of the signals will be illustrated.
CitationLeisten, P., Bishop, N., and Spieth, A., "Frequency Domain Fatigue Analysis of Exhaust Systems," SAE Technical Paper 2018-01-1396, 2018, https://doi.org/10.4271/2018-01-1396.
Data Sets - Support Documents
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- Thesing , T. and Bishop , N. Modern Methods for Random Fatigue of Automotive Parts SAE Tech Paper 2016-01-0372 April 2016 10.4271/2016-01-0372
- Ferreira , W.G. , Meehan , T.S. , Bishop , N. , and Cardoso , V.M. Comparative Study of Automotive System Fatigue Models Processed in the Time and Frequency Domain SAE Technical Paper 2016-01-0377 April 2016 10.4271/2016-01-0377
- Bishop , N. , Kerr , S. , Murthy , P. , and Sweitzer , K. Time vs Frequency Domain Analysis For Large Automotive Systems SAE Technical Paper 2015-01-0535 April 2015 10.4271/2015-01-0535
- Bishop , N. , Kerr , S. , and Murthy , P. Advances Relating to Fatigue Calculations for Combined Random and Deterministic Loads SAE Technical Paper 2014-01-0725 2014 10.4271/2014-01-0725
- Bishop , N. , Murthy P. , and Sweitzer , K. Advances Relating To Fatigue Calculations For Combined Random and Deterministic Loads 2013
- Nov 2016
- Bishop , N. and Sherratt , F. Fatigue life prediction from power spectral density data. Part 1, traditional approaches and Part 2, recent developments Env. Eng. 2 1989
- Bishop , N.W.M , and Sherratt , F. Finite Element Based Fatigue Calculations 2000
- 31st Oct 2008
- SAE Fatigue Design Handbook 3rd Edition - AE-22 Warrendale, PA SAE - Society of Automotive Engineers, Inc 1997
- Dowling , N.E.
- Sweitzer , K.A. , Bishop , N.W.M. , and Genberg , V.L. 2004
- Costa , E. , Bishop , N. , and Cardoso , V. Frequency FE-Based Weld Fatigue Life Prediction of Dynamic Systems SAE Technical Paper 2017-01-0355 2017 10.4271/2017-01-0355
- Datta , S. , Bishop , N. , Sweitzer , K. , and Atkins , A. Simultaneous Durability Assessment and Relative Random Analysis Under Base Shake Loading Conditions SAE Tech Paper 2017-01-0339 2017 10.4271/2017-01-0339
- Gannamani , R. , Gupta , A. , Bishop , N. , and Caserio , A. Sine on Random Vibration Fatigue June 2017
- Nienkemper , R. , and Bishop , N. Simultaneous Durability Assessment and Relative Random Analysis Under Base Shake Loading Conditions June 2017
- Udayakumar , G. , Murthy , P. , Bishop , N. , and Moolam , R. Creating Accurate Surrogate and/or Accelerated Loads for Known Models or Structural Systems Types June 2017