scholarly journals Review and Suggestion of Failure Theories in Voids Scenario for VARTM Processed Composite Materials

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 969
Author(s):  
Vivek Kumar Dhimole ◽  
Pruthvi Serrao ◽  
Chongdu Cho
Keyword(s):  
Composite Structures ◽  
Damage Mechanics ◽  
Resin Transfer Molding ◽  
Crack Density ◽  
Weight Ratio ◽  
Cost Effective ◽  
Transfer Molding ◽  
Void Defects ◽  
Current Design ◽  
Failure Theories

Fiber-reinforced composite structures are used in different applications due to their excellent strength to weight ratio. Due to cost and tool handling issues in conventional manufacturing processes, like resin transfer molding (RTM) and autoclave, vacuum-assisted resin transfer molding (VARTM) is the best choice among industries. VARTM is highly productive and cheap. However, the VARTM process produces complex, lightweight, and bulky structures, suitable for mass and cost-effective production, but the presence of voids and fiber misalignment in the final processed composite influences its strength. Voids are the primary defects, and they cannot be eliminated completely, so a design without considering void defects will entail unreliability. Many conventional failure theories were used for composite design but did not consider the effect of voids defects, thus creating misleading failure characteristics. Due to voids, stress and strain uncertainty affects failure mechanisms, such as microcrack, delamination, and fracture. That’s why a proper selection and understanding of failure theories is necessary. This review discusses previous conventional failure theories followed by work considering the void’s effect. Based on the review, a few prominent theories were suggested to estimate composite strength in the void scenario because they consider the effect of the voids through crack density, crack, or void modeling. These suggested theories were based on damage mechanics (discrete damage mechanics), fracture mechanics (virtual crack closure technique), and micromechanics (representative volume element). The suggested theories are well-established in finite element modeling (FEM), representing an effective time and money-saving tool in design strategy, with better early estimation to enhance current design practices’ effectiveness for composites. This paper gives an insight into choosing the failure theories for composites in the presence of voids, which are present in higher percentages in mass production and less-costly processes (VARTM).

Multiconstraint Optimization of Composite Structures Manufactured by Resin Transfer Molding Process

2005 ◽  
Vol 39 (4) ◽  
pp. 347-374 ◽  
Author(s):  
Chung Hae Park ◽  
Woo Il Lee ◽  
Woo Suck Han ◽  
Alain Vautrin
Keyword(s):  
Composite Structures ◽  
Resin Transfer Molding ◽  
Molding Process ◽  
Transfer Molding

A new methodology for race-tracking detection and criticality in resin transfer molding process using pressure sensors

2018 ◽  
Vol 52 (29) ◽  
pp. 4087-4103 ◽  
Author(s):  
Nihad A Siddig ◽  
Christophe Binetruy ◽  
Elena Syerko ◽  
Pavel Simacek ◽  
Suresh Advani
Keyword(s):  
Pressure Gradient ◽  
Resin Transfer Molding ◽  
Pressure Sensors ◽  
General Rule ◽  
Cost Effective ◽  
Flow Patterns ◽  
Manufacturing Strategy ◽  
Molding Process ◽  
Transfer Molding ◽  
Injection Process

In this study, a simplified cost effective simulation-based methodology is proposed to assist manufacturing engineers in the design and development phase of the resin transfer molding process. Race-tracking is unavoidable in the resin transfer molding and can lead to entrapment of air pockets, which results in parts being discarded as scrap. A purely numerical methodology is presented to distinguish between the critical and non-critical race-tracking scenarios, that will guide the design and production engineers plan an efficient and effective manufacturing strategy. The detection methodology is based on computing the pressure evolution with time during the injection process. The novelty relies on the superimposition of the computed pressure gradient maps that reveals unsuspected common features in the numerous race-tracking cases investigated in the various geometries of increasing complexity considered. The pressure sensors are meant to detect and evaluate different race-tracking scenarios and their level of criticality. The minimum number and locations of pressure sensors arise directly from the highest pressure gradient zones for simple geometries. Sensors placement guidelines are introduced for a simple rectangular shape, then this information is used to qualitatively apply the guidelines to parts of more complex shapes. A general rule that all parts, no matter how complex, can be considered as a combination of simpler ones is presented. Furthermore, a new failure criterion is proposed based on the flow patterns that highlights the likely flow patterns to entrap voids.

scholarly journals Application of discrete damage mechanics for determination of the crack density in composite laminates

2020 ◽  
Vol 310 ◽  
pp. 00002
Author(s):  
Milan Žmindák ◽  
Eva Kormaníková ◽  
Pavol Novák ◽  
Josef Soukup ◽  
Kamila Kotrasová
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Composite Structures ◽  
Damage Mechanics ◽  
Crack Density ◽  
Matrix Cracking ◽  
Mapping Algorithm ◽  
Damage Initiation ◽  
Return Mapping

The finite element method (FEM) is one of the most widely and most popular numerical methods for analyzing damage of composite structures, In this paper discrete damage mechanics (DDM) is used to predict inter-laminar transverse and shear damage initiation and evolution in terms of the fracture toughness of the laminate. ANSYS commercial software is used for analysis of layered plate composite structure reinforced with long unidirectional fibers with Carbon/Epoxy material. Because ANSYS does not have a built-in capability for calculating crack density, we have to use plagin. A methodology for determination of the fracture toughness is based on fitting DDM model and these data are obtained from literature. Also, prediction of modulus vs. applied strain is contrasted with ply discount results and the effect of in situ correction of strength is highlighted. Evaluation of matrix cracking detected in lamina has been solved using return mapping algorithm.

scholarly journals Optimizing Bladder Resin Transfer Molding Process to Manufacture Complex, Thin-Ply Thermoplastic Tubular Composite Structures: An Experimental Case Study

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4093
Author(s):  
Somen K. Bhudolia ◽  
Pavel Perrotey ◽  
Goram Gohel ◽  
Sunil C. Joshi ◽  
Pierre Gerard ◽  
...  
Keyword(s):  
Process Parameters ◽  
Composite Structures ◽  
Resin Transfer Molding ◽  
Low Permeability ◽  
Molding Process ◽  
Mechanical Fracture ◽  
Transfer Molding ◽  
Injection Process ◽  
Liquid Injection

The bladder molding process is primarily used in sporting applications but mostly with prepregs. Bladder-Assisted Resin Transfer Molding (B-RTM) presents the tremendous potential to automate and mass produce the complex hollow-composite profiles. Thin-ply, non-crimp fabrics (NCFs) provide excellent mechanical, fracture toughness, and vibration damping properties on top of the weight saving it offers to a final product. However, these fiber architectures are difficult to inject due to the resistance they provide for the polymer flow using the liquid injection process. Therefore, it is mandatory to optimize the process parameters to reduce the time for injection and simultaneously achieve better consolidation. This work presents a first, detailed, experimental case study to successfully inject a low-permeability, thin-ply, complex, thermoplastic tubular structure, and the effect of process parameters, boundary conditions, the associated manufacturing challenges, and proposed solutions are deliberated in this paper.

scholarly journals Prediction of Fill Time in Compression Resin Transfer Molding of Composite Structures

2020 ◽  
Vol 46 (3) ◽  
pp. 92-97
Author(s):  
Shigeki YASHIRO ◽  
Akira ITO ◽  
Tsubasa MATSUMIYA ◽  
Takahiro TSUJI ◽  
Yutaka OYA ◽  
...  
Keyword(s):  
Composite Structures ◽  
Resin Transfer Molding ◽  
Transfer Molding ◽  
Compression Resin Transfer Molding

scholarly journals Determination of the laminate strains using discrete damage mechanics

2019 ◽  
Vol 254 ◽  
pp. 06005
Author(s):  
Milan Žmindák ◽  
Michal Kaco ◽  
Pavol Novák ◽  
Leszek Radziszewski ◽  
Josef Soukup
Keyword(s):  
Fracture Toughness ◽  
Composite Structures ◽  
Damage Mechanics ◽  
Crack Density ◽  
Matrix Cracking ◽  
Mapping Algorithm ◽  
Damage Initiation ◽  
Return Mapping ◽  
Epoxy Material

In this paper discrete damage mechanics (DDM) is used to predict inter-laminar transverse and shear damage initiation and evolution in terms of the fracture toughness of the laminate. The finite element method (FEM) is one of the most widely and most popular numerical methods for analyzing composite structures, therefore ANSYS commercial software is used for analysis of layered plate composite structure reinforced with long unidirectional fibers with Carbon/Epoxy material. Because ANSYS does not have a built-in capability for calculating crack density, we have to use plugin. A methodology for determination of the fracture toughness is based on fitting DDM model and these data are obtained from literature. Also, prediction of modulus vs. applied strain is contrasted with ply discount results and the effect of in situ correction of strength is highlighted. Evaluation of matrix cracking detected in lamina has been solved using return mapping algorithm.

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