Berücksichtigung zyklischer Materialdegradation in der Crashsimulation kurzfaserverstärkter Thermoplaste/Consideration of Cyclic Material Degradation in the Crash Simulation of Short-fibre-reinforced Thermoplastics

Witzgall, Christian; Huber, Martin; Wartzack, Sandro

doi:10.37544/0720-5953-2020-01-02-78

Cited by 5 publications

(4 citation statements)

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“…Our approach for interpolation was the use of a so-called S-N surface, which was derived and used by Witzgall and Wartzack in [33]. In this approach, using the results of different fibre orientations and including a failure criterion, a continuous surface was drawn that indicates the stress that can be carried.…”

Section: Interpolation Of Arbitrary Fibre Orientations In Fatigue Lifementioning

confidence: 99%

Enhancing the Design of Experiments on the Fatigue Life Characterisation of Fibre-Reinforced Plastics by Incorporating Artificial Neural Networks

Witzgall,

Ashhab,

Wartzack

2024

Materials

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Fatigue life testing is a complex and costly matter, especially in the case of fibre-reinforced thermoplastics, where other parameters in addition to force alone must be taken into account. The number of tests required therefore increases significantly, especially if the influence of different fibre orientations is to be taken into account. It is therefore important to gain the greatest possible amount of knowledge from the limited number of available tests. In order to achieve this, this study aims to utilise adaptive sampling, which is used in numerous areas of computational engineering, for the design of experiments on fatigue life testing. Artificial neural networks (ANNs) are therefore trained on data for the short-fibre-reinforced material PBT GF30, and their areas of greatest model uncertainty are queried. This was undertaken with ANNs from various numbers of hidden layers, which were analysed for their performance. The ideal case turned out to be four hidden layers, for which a squared error as small as 1 × 10−3 was recorded. Locally resolved, the ANN was used to identify the region of greatest uncertainty for samples of vertical orientation and small numbers of cycles. With information such as this, additional data can be obtained in such uncertain regions in order to improve the model prediction—almost halving the recorded error to only 0.55 × 10−3. In this way, a model of comparable value can be found with less experimental effort, or a model of better quality can be set up with the same experimental effort.

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Section: Interpolation Of Arbitrary Fibre Orientations In Fatigue Lifementioning

confidence: 99%

Enhancing the Design of Experiments on the Fatigue Life Characterisation of Fibre-Reinforced Plastics by Incorporating Artificial Neural Networks

Witzgall,

Ashhab,

Wartzack

2024

Materials

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“…In previous work, an approach was developed to investigate the fatigue behaviour of short-fibre-reinforced thermoplastics and the influence of material fatigue on the residual strength [ 13 , 14 , 15 ]. The overall approach aims at predicting the crash-relevant material behaviour and therefore also takes into account the effects of the strain rate on the failure stress.…”

Section: Modelling Residual Properties After Fatigue Damagementioning

confidence: 99%

Fatigue Behaviour and Its Effect on the Residual Strength of Long-Fibre-Reinforced Thermoplastic PP LGF30

Witzgall,

Gadinger,

Wartzack

2023

Materials

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It is undeniable that mechanical properties, such as the stiffness or residual strength of fibre-reinforced thermoplastics, are adversely affected by fatigue damage caused by cyclic loading. In order to quantify and predict this damage influence, a calculation approach was developed in the past for the subgroup of short-fibre-reinforced thermoplastics. In order to test and expand the applicability of this approach to the field of long-fibre-reinforced thermoplastics, the decrease in mechanical properties is investigated experimentally in this paper using PP LGF30, propylene reinforced with long glass fibres, as an example. The paper describes both the fatigue behaviour and the residual strength of the material after fatigue damage. A decrease in the residual strength of up to about 35% could be recorded. The paper also presents a modelling approach that predicts the orientation-dependent fatigue strength of the material, and furthermore allows for the calculation of its residual strength as a function of fatigue damage. The novelty of the contribution lies in the continuous modelling of fatigue behaviour for arbitrary oriented samples of long-fibre-reinforced thermoplastics and also in the prediction of its residual strength depending on previously induced fatigue damage.

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“…The material has already been extensively characterised under static, highly dynamic, and cyclic conditions in previous work, so that a broad knowledge of the material behaviour is already available. The coupon-level experiments used for this are described in detail in [37,38] The cross-ribbed beams employed for the bending experiments are constructed from a U-shaped profile, which is strengthened in the middle by two X-shaped struts ("XX-Rib") [39]. The design is modelled on that of parts such as front beams or licence plate carriers, which likewise feature cross-ribbing on their rear sections to enhance rigidity.…”

Section: Description Of Materials and Specimen Geometrymentioning

confidence: 99%

Fatigue Damage of Short Fibre-Reinforced Thermoplastics in Crashworthiness Simulation

Witzgall,

Wartzack

2023

Applied Mechanics

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Service loads repeatedly stress components on a regular basis and lead to fatigue damage in the material. In the case of components made of short fibre-reinforced thermoplastics, which are also crash-relevant in addition to only bearing service loads, however, a significant deterioration in mechanical properties can be observed after fatigue damage has been introduced. This is where the approach presented in this paper comes in: in order to enable a realistic simulation of such components in their used conditions, the material data are assigned depending on previously determined damage. The approach, which combines the domains of highly dynamic and cyclic experiments as well as different types of numerical simulations, is tested for its performance in the present paper. For this purpose, component tests are carried out on cross-rib beams, which serve to validate the method. The novelty and uniqueness of this paper lies in the linking of fatigue life and crashworthiness considerations for short fibre-reinforced thermoplastics, which, in this case, is raised to a new level by considering the component level for the first time.

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Berücksichtigung zyklischer Materialdegradation in der Crashsimulation kurzfaserverstärkter Thermoplaste/Consideration of Cyclic Material Degradation in the Crash Simulation of Short-fibre-reinforced Thermoplastics

Cited by 5 publications

References 0 publications

Enhancing the Design of Experiments on the Fatigue Life Characterisation of Fibre-Reinforced Plastics by Incorporating Artificial Neural Networks

Enhancing the Design of Experiments on the Fatigue Life Characterisation of Fibre-Reinforced Plastics by Incorporating Artificial Neural Networks

Fatigue Behaviour and Its Effect on the Residual Strength of Long-Fibre-Reinforced Thermoplastic PP LGF30

Fatigue Damage of Short Fibre-Reinforced Thermoplastics in Crashworthiness Simulation

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