Residual-Stress Induced Damage in Composite Materials.

1985 ◽  
Author(s):  
Y. Weitsman
Keyword(s):  
Residual Stress ◽  
Composite Materials

Curing Residual Strain Monitoring of Carbon Fiber Reinforced Polymer Composite Using Notched Long-Period Fiber Grating

2018 ◽  
Vol 26 (1) ◽  
pp. 27-34
Author(s):  
Ke-Ping Ma ◽  
Chao-Wei Wu ◽  
Bo-Lan Fang ◽  
Chia-Chin Chiang
Keyword(s):  
Residual Stress ◽  
Composite Materials ◽  
Residual Strain ◽  
Structural Engineering ◽  
Fiber Grating ◽  
Long Period Fiber Grating ◽  
Long Period ◽  
Strain Monitoring ◽  
Residual Strains ◽  
Period Fiber Grating

Composite materials are widely used in the aerospace industry and structural engineering owing to their advantageous mechanical properties. The curing monitoring of composite material is important to ensure the quality of the curing process, especially for the characterization of residual strains after manufacturing. In this study, we present a notched long-period fiber grating (NLPFG) with a period of 650 μm and a diameter of 66 μm that can be used in the curing monitoring of composite materials. This NLPFG was embedded into the middle layers of composite materials in order to determine the curing residual stress exhibited by the materials. The experimental results showed that the residual stress was about 107 MPa and the axial residual strain was 1490 με. Therefore, the proposed NLPFG has potential as a strain sensor for composite materials.

scholarly journals Multiscale characterization and representation of composite materials during processing

2016 ◽  
Vol 374 (2071) ◽  
pp. 20150278 ◽  
Author(s):  
Navid Zobeiry ◽  
Alireza Forghani ◽  
Chao Li ◽  
Kamyar Gordnian ◽  
Ryan Thorpe ◽  
...  
Keyword(s):  
Residual Stress ◽  
Composite Materials ◽  
Process Simulation ◽  
Structural Integrity ◽  
Mechanical Performance ◽  
Constitutive Models ◽  
Separated Flow ◽  
Complex Model ◽  
Dimensional Changes ◽  
Cure Cycle

Given the importance of residual stresses and dimensional changes in composites manufacturing, process simulation has been the focus of many studies in recent years. Consequently, various constitutive models and simulation approaches have been developed and implemented for composites process simulation. In this paper, various constitutive models, ranging from elastic to nonlinear viscoelastic; and simulation approaches ranging from separated flow/solid phases to multiscale integrated phases are presented and their applicability for process simulation is discussed. Attention has been paid to practical aspects of the problem where the complexity of the model coupled with the complexity and size scaling of the structure increases the characterization and simulation costs. Two specific approaches and their application are presented in detail: the pseudo-viscoelastic cure hardening instantaneously linear elastic (CHILE) and linear viscoelastic (VE). It is shown that CHILE can predict the residual stress formation in simple cure cycles such as the one-hold cycle for HEXCEL AS4/8552 where the material does not devitrify during processing. It is also shown that using this simple approach, the cure cycle can be modified to lower the residual stress level and therefore increase the mechanical performance of the composite laminate. For a more complex cure cycle where the material is devitrified during a post-cure, it is shown that a more complex model such as VE is required. This article is part of the themed issue ‘Multiscale modelling of the structural integrity of composite materials’.

scholarly journals Electromechanical Response and Residual Thermal Stress of Metal-Core Piezoelectric Fiber /Al Matrix Composites

Sensors ◽  
2020 ◽  
Vol 20 (20) ◽  
pp. 5799
Author(s):  
Yinli Wang ◽  
Tetsuro Yanaseko ◽  
Hiroki Kurita ◽  
Hiroshi Sato ◽  
Hiroshi Asanuma ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Composite Materials ◽  
Output Voltage ◽  
Residual Thermal Stress ◽  
Piezoelectric Composite ◽  
Concentrated Load ◽  
Position Detection ◽  
Al Matrix ◽  
Piezoelectric Fiber

It is well known that the curing residual stress induced during a fabrication process has a great influence on the performance of piezoelectric composite devices. The purpose of this work was to evaluate the residual thermal stress of lead zirconate titanate piezoelectric fiber aluminum (Al) matrix (piezoelectric fiber/Al) composites generated during fabrication numerically and experimentally and to understand the effect of the residual thermal stress on the electromechanical response. The three-dimensional finite element method was employed, and the residual stress generated during the solidification process of the Al matrix was calculated. The output voltage was also calculated in the analysis when putting stresses on the composite materials in the length direction of the piezoelectric fiber. It was shown that the cooling from higher temperatures increases the electromechanical conversion capability. Furthermore, we also performed the simulation, and we recorded the output voltage under concentrated load to investigate its application as a load position detection sensor, and we also discussed the influence of the position by changing the modeling with a different fiber position in the Al. The residual stress of hot press molded piezoelectric fiber/Al composite was then measured, and the comparison was made with the calculated values. The simulation results revealed that our model predictions reproduced and explained the experimental observations of curing residual stress. After this study, similar models of composite materials can be analyzed by this simulation, and the result can be used to design piezoelectric composite materials.

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