A thermodynamic framework for additive manufacturing, using amorphous polymers, capable of predicting residual stress, warpage and shrinkage

Sreejith, P.; Kannan, K.; Rajagopal, K. R.

doi:10.1016/j.ijengsci.2020.103412

Cited by 41 publications

(12 citation statements)

References 46 publications

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“…The biggest issue faced by small module plastic gears is the serious shortage of dimensional accuracy. Due to the inherent shrinkage of polymer [ 14 , 15 , 16 ], plastic parts could experience a non-linear shrinkage in the stage of pressure holding and cooling, resulting in deviation between the final plastic part and the mold cavity geometry. Moreover, the overall size of small module plastic gears is smaller, and the shape deviation has a more significant impact on its dimensional accuracy.…”

Section: Introductionmentioning

confidence: 99%

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

2021

Polymers

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This paper was aimed at finding out the solution to the problem of insufficient dimensional accuracy caused by non-linear shrinkage deformation during injection molding of small module plastic gears. A practical numerical approach was proposed to characterize the non-linear shrinkage and optimize the dimensional deviation of the small module plastic gears. Specifically, Moldflow analysis was applied to visually simulate the shrinkage process of small module plastic gears during injection molding. A 3D shrinkage gear model was obtained and exported to compare with the designed gear model. After analyzing the non-linear shrinkage characteristics, the dimensional deviation of the addendum circle diameter and root circle diameter was investigated by orthogonal experiments. In the end, a high-speed cooling concept for the mold plate and the gear cavity was proposed to optimize the dimensional deviation. It was confirmed that the cooling rate is the most influential factor on the non-linear shrinkage of the injection-molded small module plastic gears. The dimensional deviation of the addendum circle diameter and the root circle diameter can be reduced by 22.79% and 22.99% with the proposed high-speed cooling concept, respectively.

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Section: Introductionmentioning

confidence: 99%

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

2021

Polymers

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“…Upon unloading, this new configuration then competes with the original stress-free configuration, which in turn leads to a permanent strain. The phenomenological concept of evolving natural configuration we are going to use has been successfully used in mathematical modelling of various inelastic phenomena, see Rajagopal and Srinivasa (2000) and Rajagopal and Srinivasa (2004a,b) for an early uses of the concept of natural configuration, and also Sodhi and Rao (2010) and Sreejith et al (2021) for newer applications and further reverences. In our case we proceed as follows.…”

Section: 3mentioning

confidence: 99%

A thermodynamic framework for non-isothermal phenomenological models of Mullins effect

Cichra¹,

Gazca-Orozco²,

Průša³

et al. 2022

Preprint

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The Mullins effect is a common name for a family of intriguing inelastic responses of various solid materials, in particular filled rubbers. Given the importance of the Mullins effect, there have been many attempts to develop mathematical models describing the effect. However, most of available models focus exclusively on the mechanical response, and are restricted to the idealised isothermal setting. We lift the restriction to isothermal processes, and we propose a full thermodynamic framework for a class of phenomenological models of the Mullins effect. In particular, we identify energy storage mechanisms (Helmholtz free energy) and entropy production mechanisms that on the level of stress-strain relation lead to the idealised Mullins effect or to the Mullins effect with permanent strain. The models constructed within the proposed framework can be used in the modelling of fully coupled thermo-mechanical processes, and the models are guaranteed to be consistent with the laws of thermodynamics.

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“…This severe thermo-mechanical loading creates significant defects in 3D-printed parts, commonly referred as warping [11], due to the creation of residual thermal internal stresses during the cooling of the polymer [50]. Currently, to estimate these internal stresses, finite element methods in commercial codes [29,28] solve the thermo-mechanical structural problem by integrating thermo-viscoelastic behavior laws for the polymer material [5,58].…”

Section: Introductionmentioning

confidence: 99%

Effective thermo-viscoelastic behavior of short fiber reinforced thermo-rheologically simple polymers: An application to high temperature fiber reinforced additive manufacturing

Suarez-Afanador

Cornaggia

Lahellec

et al. 2022

European Journal of Mechanics - A/Solids

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A thermodynamic framework for additive manufacturing, using amorphous polymers, capable of predicting residual stress, warpage and shrinkage

Cited by 41 publications

References 46 publications

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

A thermodynamic framework for non-isothermal phenomenological models of Mullins effect

Effective thermo-viscoelastic behavior of short fiber reinforced thermo-rheologically simple polymers: An application to high temperature fiber reinforced additive manufacturing

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