Lifetime assessment of anisotropic materials by the example short fibre reinforced plastic

Primetzhofer, Andreas; Stadler, Gabriel; Pinter, Gerald; Grün, Florian

doi:10.1016/j.ijfatigue.2018.06.013

Cited by 9 publications

(10 citation statements)

References 23 publications

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“…In order to use the material potential for different specific applications, the fatigue limits of the used materials must be known. Usually, fatigue tests are performed to obtain the data for a lifetime estimation of short fibre reinforced polymers [1]. These calculations consider several influence factors, like local fibre orientation [2,3], temperature, and notches [4].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Viscoelastic Behaviour on the Lifetime of Short Fibre Reinforced Polymers

et al. 2020

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Short fibre reinforced polymers are getting more important for structural applications. Becasue of lightweight actions, components are designed for a specific application and lifetime. The bearable numbers of cycles can be estimated using material data and models for the consideration of influence factors. Further static loadings affect material behaviour, which influences the component lifetime. Commonly used models are not able to capture these effects. Therefore, material tests, with different load sequences, on 40% short glass fibre reinforced polypropylene have been performed. These sequences are combinations of cyclic and static loads at different, defined levels. Our research shows a lifetime elongation or reduction of a polymer, depending on the amount of static load time and quantity. For a certain stress level, the time to failure can be elongated or shortened more than a decade by another stress level, as compared to pure cyclic load. Additionally, the stiffness development of the composite is investigated in order to capture the damage course. Accordingly, these effects needed to be considered in lifetime prediction.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Viscoelastic Behaviour on the Lifetime of Short Fibre Reinforced Polymers

et al. 2020

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“…Within this simulation chain, several models and methods are combined to predict the lifetime (depending on the material), the load case, and the ambient conditions. [1][2][3] These models in particular describe the influence of fiber orientation [4][5][6], mean stress [7,8], notch effect [9], and temperature [10][11][12]. In this work, special attention is paid to the local fiber orientation, as it has a major influence on the mechanical behavior.…”

Section: Introductionmentioning

confidence: 99%

“…The influences can then be described by different models. In [1][2][3]28,29] the most common stress-based simulation techniques, applicable on parts, are described. To be able to compare the actual stress to the bearable stress (stress which can be applied to reach a certain lifetime or cycles to failure), test data must be stored in some way.…”

Section: Introductionmentioning

confidence: 99%

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Model Calibration and Data Set Determination Considering the Local Micro-Structure for Short Fiber Reinforced Polymers

et al. 2021

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To ensure the usability of parts made of fiber-reinforced polymers, a lifetime assessment has to be made in an early stage of the development process. To describe the whole life cycle of these parts, continuous simulation chains can be used. From production to the end of the service life, all influences are mapped virtually. The later material strength is already given after the manufacturing process due to the process dependent fiber alignment. To be able to describe this fiber orientation within the lifetime assessment, this paper presents an approach for model calibration and data set determination to consider the local micro-structure. Therefore, quasi-static and cyclic tests were performed on specimens with longitudinal and transversal fiber orientation. A supplementary failure analysis provides additional information about the local micro-structure. The local fiber orientation is determined with µCT (micro computer tomography)-measurements, correlated to the extraction positions of the specimen, and implemented in a dataset. With an attached lifetime calculation on a demonstrator, a major influence of the local micro-structure on the calculation results can be shown. Therefore, it is indispensable to consider the local fiber orientation in the data set determination of short fiber reinforced polymers.

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“…The specimens were produced by injection moulding and used dry as moulded. Due to the moulding-process an averaged fibre orientation, represented by the eigenvalues of the 2-order orientation tensor a[3], along the longitudinal axis of…”

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Applicability of Strain Controlled Cyclic Tests for Short Fibre Reinforced Polymers

Primetzhofer¹,

Stadler²,

Pinter³

et al. 2019

MSA

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To develop parts, made of short glas fibre reinforced (sgfr) polymers for industrial purposes, a comprehensive material knowledge is necessary. Especially the material behaviour under cyclic loads has a great influence on the life time of parts. Parts are often used under complex load cases (stress state, temperature, ...), therefore it is indispensable to understand the effect of the main influence factors. High loads within load histories as well as stress concentrations can lead to plastic deformations. To cover this in an early stage of the development process, a closed simulation chain should be established. Therefore, the applicability of common material models (e.g. fatigue criteria according to Ramberg-Osgood) has to be studied first, the models have to be adapted or even new models have to be found for sgfr materials. This work focuses on the applicability of strain controlled cyclic tests for glass fibre reinforced polymers. Hereby the cyclic stress rearrangement in the low cycle regime of the S/N-curve can be described. Therefore, tests were performed on a 50 wt% sgfr partial aromatic polyamide. For the fatigue tests un-notched, injection moulded specimen were used. The tests show a principal applicability of strain controlled LCF-tests for sgfr polymers.

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Lifetime assessment of anisotropic materials by the example short fibre reinforced plastic

Cited by 9 publications

References 23 publications

Investigation of the Influence of Viscoelastic Behaviour on the Lifetime of Short Fibre Reinforced Polymers

Investigation of the Influence of Viscoelastic Behaviour on the Lifetime of Short Fibre Reinforced Polymers

Model Calibration and Data Set Determination Considering the Local Micro-Structure for Short Fiber Reinforced Polymers

Applicability of Strain Controlled Cyclic Tests for Short Fibre Reinforced Polymers

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