Improvement of warpage prediction through integrative simulation approach for thermoplastic material

Divekar, Mahesh; Gaval, Vivek; Wonisch, Andreas

doi:10.1177/0892705720930746

Cited by 8 publications

(10 citation statements)

References 15 publications

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“…This reduction in tensile modulus and stress at the break may be attributed to material degradation because of excess pressure, which is difficult to analyze from microscopic evaluation in this study. However, in general, high pressure increases the specific volume which develops residual stresses 22 and this may be one of the reasons for the drop in tensile strength and the increase in elongation of the specimen.…”

Section: Resultsmentioning

confidence: 99%

Effect of packing pressure on stagnation weld-line strength for thermoplastic semicrystalline glass fiber reinforced material

Jadhav

Gaval

Divekar³

et al. 2022

Journal of Thermoplastic Composite Materials

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Weld-Line in an injection molded part develops when two or more melt fronts are converged together. The weld-line is unavoidable when the design is complex where two melt flow fronts are mating each other head-to-head, this mating area is mechanically weak compared to other portions of the modeled part. The decrease in strength in the weld-line area can be attributed to several factors like molecular diffusion, fiber orientation effect, unoptimized process conditions, surface tension effect, internal residual stresses, etc. The strength of the weld-line area can be increased by optimizing injection molding process parameters like melt temperature, injection speed, packing pressure, changing gate type and location, etc. The present work focuses on studying the effect of packing pressure on strength of stagnation weld-line. This has been examined with experimental testing and scanning electron micrographs of the fractured surface on the weld-line and without weld-line specimens. The special injection mold is designed and fabricated to produce plaques having stagnation weld-line. The plaques are prepared out of 30% glass-filled Polyamide 6 material. The four sets of plaques are produced by changing the magnitude of packing pressure equal to 60% of filling pressure, with increment of 20% up to 120% of filling pressure. The tensile test specimens are machined on these plaques for two different angular orientations and testing is conducted as per ISO 527-2. The results demonstrated that, without weld-line specimens, the tensile modulus, stress at break marginally increases with an increase in packing pressure, and strain at break decreases with an increase in packing pressure. However, for specimens with stagnation weld-lines, both the tensile modulus and stress at break are observed to be 42% of without weld-lines samples for minimum packing pressure. The results obtained are evident from stress-strain graphs and scanning electron micrographs.

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Section: Resultsmentioning

confidence: 99%

Effect of packing pressure on stagnation weld-line strength for thermoplastic semicrystalline glass fiber reinforced material

Jadhav

Gaval

Divekar³

et al. 2022

Journal of Thermoplastic Composite Materials

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“…The evaluation of weld-line is important in two different ways first aesthetic and second functional. [28][29][30] Both aspects have particular importance as per end application requirements.…”

Section: Importance Of Weld-line Evaluationmentioning

confidence: 99%

Weld‐lines and its strength evaluation in injection molded parts: A review

Jadhav,

Gaval,

Solanke

et al. 2023

Polymer Engineering & Sci

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Injection molding manufacturing is immensely popular nowadays because of its excellent manufacturability for complex designs produced from a wide range of different engineering plastic materials. Weld‐line is a defect that arises in injection molding when two or more flow fronts collide. The weld‐lines are undesirable from both aesthetic and functional points of view and their effect is different for varied materials, process conditions, loadings, forms of weld‐line, etc. The presence of a weld‐line weakens components locally due to insufficient intermolecular diffusion, v‐notch formation, fiber anisotropy, insufficient process conditions, and so on. When a component is under load, crack propagation usually begins with a weak weld‐line area. Therefore, the designer should anticipate the presence of weld‐lines and their strength to avoid failure of components during operation. In this article, the review of published research work on weld‐line formation during injection molding has been summarized. The review focuses on the phenomenon of weld‐line formation, the type of weld‐lines, and the importance of weld‐line evaluations. The theoretical, experimental, and computational approaches to analyzing weld‐line and its strength are covered in detail. At last, methods for reducing weld‐lines and increasing the strength of weld‐line area have been discussed. This review also gathers data on weld‐line strength with respect to different materials.Highlights Details of weld‐line formation and its types. Importance of weld‐line evaluation. Methods of weld‐line strength evaluation. Methods of reduction of the number of weld‐line and its effect. Summary of weld‐line strength for different material.

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“…Due to the presence of the thermoplastic matrix, CFRTP composites typically exhibit viscoelastic behavior at the macro‐scale. Viscoelasticity is essential in the hot stamping process, resulting in surface wrinkling, [ 14 ] warpage [ 15 ] and distortion, [ 16 ] which should be accounted for in the accurate simulation. Guzman‐Maldonado et al [ 14 ] incorporated a nonlinear viscoelastic model into the in‐plane shear mode during hot stamping modeling for woven composites and successfully simulated wrinkle formation during stamping at low temperatures and high strain rates.…”

Section: Introductionmentioning

confidence: 99%

A dual‐scale three‐dimensional thermo‐viscoelastic model for the hot stamping simulation of thermoplastic composites

et al. 2022

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Existing hot stamping simulations are performed at the macroscopic scale, making optimizing process parameters for a new composite system time‐consuming. This paper develops a dual‐scale three‐dimensional thermos‐viscoelastic model based on a numerical homogenization approach to accurately predict the structural deformation of thermoplastic composite laminates during hot stamping. The viscoelastic homogenization model is developed on representative volume elements using temperature‐dependent viscoelastic parameters determined from thermo‐mechanical tests. The effective properties of the composites are identified from the homogenization results, which are then combined with the experimentally measured thermal behavior into a numerical model of the hot stamping process. The developed model is validated by the agreement between the finite element homogenization results and the predictions made using the determined parameters. The simulated warpage of the molded part also agrees well with the experimental measurements. The developed dual‐scale model can be used to predict the effective thermomechanical properties of composites. Moreover, it can also be integrated into numerical tools for structural design and process optimization of thermoplastic composites.

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Improvement of warpage prediction through integrative simulation approach for thermoplastic material

Cited by 8 publications

References 15 publications

Effect of packing pressure on stagnation weld-line strength for thermoplastic semicrystalline glass fiber reinforced material

Effect of packing pressure on stagnation weld-line strength for thermoplastic semicrystalline glass fiber reinforced material

Weld‐lines and its strength evaluation in injection molded parts: A review

A dual‐scale three‐dimensional thermo‐viscoelastic model for the hot stamping simulation of thermoplastic composites

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