Measurement and Numerical Simulation of Void and Warpage in Glass Fiber Reinforced Molded Chunky Parts

Kleindel, Stefan; Salaberger, Dietmar; Eder, Roland; Schretter, Herwig; Hochenauer, Christoph

doi:10.3139/217.2984

Cited by 5 publications

(2 citation statements)

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“…The standard states that this measurement technique is only applicable for short fiber‐reinforced materials. Although this standard exists, only one publication was found that specifically analyzed the fiber length according to this standard and cited it . Nevertheless, most measurement procedures in the field are similar to the ISO:22314 standard.…”

Section: State‐of‐the‐artmentioning

confidence: 99%

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

et al. 2017

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The residual fiber length in a molded part is one of the most important microstructural properties of discontinuous fiber‐reinforced composites. While there have been several research studies characterizing the process‐induced fiber length reduction, the measurement procedures vary substantially, calling into question the comparability of reported results. This article introduces a newly developed measurement procedure that aims to provide accurate, repeatable, robust, and time efficient fiber length analyses. A comprehensive study of measurement techniques was performed comparing commercially available systems and the conventional approach of measuring the fiber length manually. The results emphasize the need for a standardized procedure to characterize the fiber length distribution and the risk of generating inadequate results through improper sample preparation. The developed measurement technique was tested and compared for an experimental study of fiber breakage in injection molding. For a simple plaque geometry, the residual fiber length along the flow path was obtained for a long glass fiber‐reinforced polypropylene at 30 and 40%wt for varying process conditions. The new measurement technique showed accurate and repeatable results. The results of the injection molding study showed that screw speed and back pressure are important factors that drive fiber breakage. An increase in back pressure from 13 to 50 bar and screw speed from 27 to 35 rpm reduces the weight‐average fiber length by 37.5%. POLYM. COMPOS., 39:4058–4070, 2018. © 2017 Society of Plastics Engineers

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Section: State‐of‐the‐artmentioning

confidence: 99%

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

et al. 2017

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“…The voids, being undetectable by visual observation, may exert the most detrimental effect on the mechanical performance of injection-moulded components, weakening their capacity to withstand the loads while in service and leading to crack initiation and failure [ 10 , 11 , 12 ]. The influence of the excessive shrinkage, in chunky plastic parts moulded from fiber reinforced composites, was highlighted as the main cause of the occurrence of voids and warpage by Kleindel et al [ 13 ]. Their conclusions were corroborated by the findings of Vaxman et al for thick-walled, injection-moulded Noryl (polyphenylene-oxide/polystyrene) components [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Computer-Aided Reengineering towards Plastic Part Failure Minimization

et al. 2021

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The work reported here intends to identify and mitigate the causes for failure in a plastic faucet holder, a part of an integral float faucet with a well-documented history of fracture occurrence. A methodology for the identification of hidden internal defects in plastic parts and the elaboration of the required corrective actions towards quality improvement is, therefore, presented. Firstly, part defects were identified via injection moulding process numerical simulation. The latter has enabled the prediction of an excessive volumetric shrinkage at the core of the faucet holder, highlighting the presence of internal voids and, hence, the possible deterioration of the load-bearing capacity. The supposition was later confirmed by X-ray topography scans. Part reengineering, consisting of localized thickness reduction, was the option chosen for decreasing the high shrinkage at the core. For validation purposes, structural analyses were carried out, with and without accounting for the injection moulding processing history. The results obtained during part structural analysis have enabled us to conclude that, when taking into account the residual stresses generated during injection moulding, the analysis more closely reflects the experimental data and allows us to implicitly envisage the propensity to fracture. Moreover, the part modifications, undertaken during the faucet holder reengineering, led to the reduction of the cumulative (processing and imposed by load) stresses by 50%, when compared to the original design analysed.

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