scholarly journals Effect of Manufacturing on the Transverse Response of Polymer Matrix Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2491
Author(s):  
Sagar P. Shah ◽  
Marianna Maiarù
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Process Modeling ◽  
Polymer Matrix Composites ◽  
Effect Study ◽  
Matrix Composites ◽  
Computationally Efficient ◽  
Thermoset Composites ◽  
Residual Stress State ◽  
Composite Stiffness

The effect of residual stress build-up on the transverse properties of thermoset composites is studied through direct and inverse process modeling approaches. Progressive damage analysis is implemented to characterize composite stiffness and strength of cured composites microstructures. A size effect study is proposed to define the appropriate dimensions of Representative Volume Elements (RVEs). A comparison between periodic (PBCs) and flat (FBCs) boundary conditions during curing is performed on converged RVEs to establish computationally efficient methodologies. Transverse properties are analyzed as a function of the fiber packing through the nearest fiber distance statistical descriptor. A reasonable mechanical equivalence is achieved for RVEs consisting of 40 fibers. It has been found that process-induced residual stresses and fiber packing significantly contribute to the scatter in composites transverse strength. Variation of ±5% in average strength and 18% in standard deviation are observed with respect to ideally cured RVEs that neglect residual stresses. It is established that process modeling is needed to optimize the residual stress state and improve composite performance.

Residual stress and failure analyses of polymer matrix composites considering thermal cycling and temperature effects based on classical laminate plate theory

2018 ◽  
Vol 53 (21) ◽  
pp. 3021-3032 ◽  
Author(s):  
AR Ghasemi ◽  
A Tabatabaeian ◽  
M Moradi
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Thermal Cycling ◽  
Polymer Matrix Composites ◽  
Plate Theory ◽  
Laminate Plate ◽  
Failure Behavior ◽  
Matrix Composites ◽  
Failure Index ◽  
Classical Laminate Plate Theory

The effects of temperature and thermal cycling on the residual stress and failure behavior of different polymer matrix composites have been investigated in this paper. A new algorithm within the framework of the classical laminate plate theory (CLPT) has been presented to calculate the residual stresses. The modified Tsai-Wu failure criterion has been employed to study the failure behavior of different stacking sequences. Numerical results show that the residual stress and failure index of the composites decrease with the increase of the temperature. It has also been established that thermal cycling condition leads to reduction of the residual stresses and increment of the failure index.

scholarly journals Process Modeling of Thermoset Composites used for Wind Blade Manufacturing

2021 ◽  
Author(s):  
Sagar P. Shah ◽  
Sagar U. Patil ◽  
Christopher J. Hansen ◽  
Gregory M. Odegard ◽  
Marianna Maiaru
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Wind Energy ◽  
Process Modeling ◽  
Material Characterization ◽  
Virtual Manufacturing ◽  
Stress Generation ◽  
Cure Cycle ◽  
Thermoset Composites

A computational process modeling framework, informed by accurate material characterization, is presented for virtual manufacturing of wind energy thermoset composites. Process modeling simulations of composite microstructures are carried out to predict in-situ matrix property evolution and performance-altering residual stress generation. To achieve this, comprehensive material characterization effort is carried out. A novel material property dataset for a widely-used wind energy thermoset system is generated as a function of the temperature and curing. Informed by these material properties, the ability of the process model to reliably estimate manufacturing-induced residual stresses is highlighted. For a prescribed cure cycle, in-situ elastic modulus evolution, chemical and thermal strains, and random fiber distribution are shown to significantly influence residual stress generation. The results also show that a full process modeling analysis that includes the complete cure cycle (instead of the standard approach of just considering post-processing cool-down) is necessary to accurately predict manufacturing-induced residual stresses.

Finite Element Modeling for Prediction of Residual Stresses in Fiber Reinforced Metal Matrix Composites

1993 ◽  
Author(s):  
Partha Rangaswamy ◽  
N. Jayaraman
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Matrix Material ◽  
Unit Cell ◽  
Experimental Results ◽  
Matrix Composites ◽  
Layer Removal

Abstract In metal matrix composites residual stresses developing during the cool-down process after consolidation due to mismatch in thermal expansion coefficients between the ceramic fibers and metal matrix have been predicted using finite element analysis. Conventionally, unit cell models consisting of a quarter fiber surrounded by the matrix material have been developed for analyzing this problem. Such models have successfully predicted the stresses at the fiber-matrix interface. However, experimental work to measure residual stresses have always been on surfaces far away from the interface region. In this paper, models based on the conventional unit cell (one quarter fiber), one fiber, two fibers have been analyzed. In addition, using the element birth/death options available in the FEM code, the surface layer removal process that is conventionally used in the residual stress measuring technique has been simulated in the model. Such layer removal technique allows us to determine the average surface residual stress after each layer is removed and a direct comparison with experimental results are therefore possible. The predictions are compared with experimental results of an eight-ply unidirectional composite with Ti-24Al-11 Nb as matrix material reinforced with SCS-6 fibers.

About Residual Stress State of Castings: The Case of HPDC Parts and Possible Advantages through Semi-Solid Processes

2022 ◽  
Vol 327 ◽  
pp. 272-278
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Claudio Mus ◽  
Yuji Kobayashi ◽  
Mario Rosso
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Casting Process ◽  
Ray Method ◽  
Premature Failure ◽  
Thin Walls ◽  
Residual Stress State ◽  
Semi Solid ◽  
Pressure Die Casting

Nowadays, one of the most crucial focus in the aluminium-foundry sector is the production of high-quality castings. Mainly, High-Pressure Die Casting (HPDC) is broadly adopted, since by this process is possible to realize aluminium castings with thin walls and high specific mechanical properties. On the other hand, this casting process may cause tensile states into the castings, namely residual stresses. Residual stresses may strongly affect the life of the product causing premature failure of the casting. Various methods can assess these tensile states, but the non-destructive X-Ray method is the most commonly adopted. Namely, in this work, the residual stress analysis has been performed through Sinto-Pulstec μ-X360s. Detailed measurements have been done on powertrain components realized in aluminium alloy EN AC 46000 through HPDC processes to understand and prevent dangerous residual stress state into the aluminium castings. Furthermore, a comparison with stresses induced by Rheocasting processes is underway. In fact, it is well known that Semi-Solid metal forming combines the advantages of casting and forging, solving safety and environmental problems and possibly even the residual stress state can be positively affected.

scholarly journals Influence of a modified drawing process on the resulting residual stress state of cold drawn wire

2018 ◽  
Vol 190 ◽  
pp. 04004
Author(s):  
Markus Baumann ◽  
Alexander Graf ◽  
René Selbmann ◽  
Katrin Brömmelhoff ◽  
Verena Kräusel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Wire Drawing ◽  
Industrial Applications ◽  
Drawing Process ◽  
Die Geometry ◽  
Residual Stress State ◽  
Drawing Die ◽  
Process Modification ◽  
The Wire

Torsion bars are used in automotive engineering as well as in other industrial applications. Such elements are produced by bending cold drawn wires. In conventional drawing processes tensile residual stresses occur near the surface of the wire. Small bending radii, which are required in limited assembly spaces, result in component failure due to reduced formability. Additional operations such as heat treatment or shot peening are necessary to influence the residual stress of the wire and to improve the dynamic stability of the torsion bar. The aim of the research is to reduce tensile residual stresses near the surface of the wire in order to eliminate process steps and to enhance formability. Therefore, a forming technology is developed by using a modified drawing die geometry on the basis of gradation extrusion. Finite element simulation is used to investigate the influences of element geometry, number of elements and process modification on the resulting residual stresses after wire drawing of a steel alloy. The results are evaluated and compared with the conventional wire drawing process. Furthermore, the requirements for the design of an experimental test device will be outlined as well as the measurement of the residual stresses by using X-ray diffraction.

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