PSI - Issue 17

Available online at www.sciencedirect.com Structural I tegrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 17 (2019) 589–595

ICSI 2019 The 3rd International Conference on Structural Integrity Fatigue life prediction of Polymethyl methacrylate (PMMA) polymer under random vibration loading C P Okeke a,b *, A N Thite a , J F Durodola a and M T Greenrod b a School of Engineering, Computing and Mathematics, Oxford Brookes University, Oxford – OX33 1HX, UK, email: 14101309@brookes.ac.uk , athite@brookes.ac.uk b Wipac Ltd, London Road, Buckingham, MK18 1BH, UK The objective of this paper is to develop a robust numerical fatigue life prediction model for Polymethyl Methacrylate (PMMA) polymer material of automotive lamp components subjected to random vibration loading, with consideration for material non linearity to reduce number of iterations in the design cycle. The fatigue life based on initial elastic modulus and secant modulus is predicted using ANSYS software and compared to the experimentally obtained fatigue life. Three fatigue life prediction models, Steinberg, Narrow-Band and Wirsching were used. Twelve specimens cut-out from injection moulded optical blades of PMMA were tested to obtain the fatigue life using electrodynamic shaker. The average experimental fatigue life was obtained from the twelve specimens tested. The use of initial elastic range based modulus gives fatigue life that is 43% lower than the experimental result, while for the secant modulus based analysis, the fatigue life accurately matches the experimental result with only 1% difference. Hence, a complete non-linear finite element model may not be necessary to estimate the fatigue life. The numerical result is based on Wirsching fatigue model, which provides a more accurate prediction than Steinberg and Narrow-Band models. ICSI 2019 The 3rd International Conference on Structural Integrity Fatigue life prediction of Polymethyl methacrylate (PMMA) polymer under random vibration loading C P Okeke a,b *, A N Thite a , J F Durodola a and M T Greenrod b a School of Engineering, Computing and Mathematics, Oxford Brookes University, Oxford – OX33 1HX, UK, email: 14101309@brookes.ac.uk , athite@brookes.ac.uk b Wipac Ltd, London Road, Buckingham, MK18 1BH, UK Abstract The objective of this paper is to develop a robust numeri al fatigue life predicti mo el for Polymethyl Methacrylate (PMMA) polymer material of automotiv lamp compon nts subjected to random vi ration loading, with consideration for material non linearity to reduce number of iterations in the design cycle. The fatigue life based on initial elastic modulus and s cant modulus is pr dicted using ANSYS software and compared to the experimentally obtained fatigue life. Three fatigue life prediction models, Steinb rg, Narrow-Band and Wirsching were used. Twelve specimens cut-out from injection moulded optical blades of PMMA ere tested to obtain the fatigue life using electrodynamic shaker. The a erage experimental fatigue life was obtained from the twelve specimens tested. The use of initial el stic range based modulus gives fatigue lif that is 43% lower than the experimental result, while for the secant modulus b sed analysis, the fatigue life accurately matches the experimental result with only 1% difference. Hence, a complete non-linear finite element model may not b necessary to estimate the fatigue life. The numerical result is based on Wirsching fatigue model, which provides a more accurate prediction than Steinberg and Narrow-Band models. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

Keywords: Fatigue life; Polymer; Material; Non-linear; Elastic; Modulus; Automotive; Lamps; Prediction model Keywords: Fatigue life; Polymer; Material; Non-linear; Elastic; Modulus; Automotive; Lamps; Prediction model

* Corresponding author. Tel.: +44-(0)1865-423011 E-mail address: c.okeke100@gmail.com; 14101309@brookes.ac.uk * Correspon ing author. Tel.: +44-(0)1865-423 1 E-mail address: c.okeke100@gmail.com; 14101309@brookes.ac.uk

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.079