Free Edge Stress Analysis of Unidirectional CFRP Laminates Based on a Homogenization Theory for Time-Dependent Composites

2013 ◽  
Vol 535-536 ◽  
pp. 397-400 ◽  
Author(s):  
Keita Goto ◽  
Tetsuya Matsuda
Keyword(s):  
Carbon Fiber ◽  
Stress Analysis ◽  
Tensile Load ◽  
Free Edge ◽  
Time Dependent ◽  
Homogenization Theory ◽  
Uniaxial Tensile ◽  
Cfrp Laminates ◽  
Reinforced Plastic ◽  
Free Edges

In this study, distributions of microscopic stress at free edges of unidirectional carbon fiber-reinforced plastic laminates (CFRP laminates) are analyzed three-dimensionally, based on a homogenization theory for time-dependent composites. For this, the homogenization theory is reconstructed for free edge problems using a traction-free boundary condition. Then, an analysis domain is reduced using the point-symmetry of the internal structure of the unidirectional CFRP laminate. Moreover, the substructure method is newly introduced into the theory to reduce the computational costs required for the analysis. The present method is then applied to the elastic-viscoplastic microscopic stress analysis at free edges of unidirectional carbon fiber/epoxy laminates subjected to an in-plane uniaxial tensile load. It is shown that complex microscopic stress distributions occur in the vicinity of the free edge, especially around fiber/matrix interface regions.

Fully-Modeled Unit Cell Analysis for Macro/Micro Elastic-Viscoplastic Behavior of Quasi-Isotropic CFRP Laminates

2014 ◽  
Vol 626 ◽  
pp. 512-517 ◽  
Author(s):  
Keita Goto ◽  
Tetsuya Matsuda ◽  
Naoto Kubota
Keyword(s):  
Carbon Fiber ◽  
Matrix Material ◽  
Tensile Load ◽  
Unit Cell ◽  
Homogenization Theory ◽  
Uniaxial Tensile ◽  
Hexagonal Prism ◽  
Cell Analysis ◽  
Cfrp Laminate ◽  
Isotropic Carbon

A fully-modeled unit cell analysis is performed to investigate the macroscopic and microscopic elastic-viscoplastic behaviors of a quasi-isotropic carbon fiber-reinforced plastic (CFRP) laminate. To this end, a quasi-isotropic CFRP laminate and its microstructure composed of carbon fibers and a matrix material are considered three-dimensionally. Then, a hexagonal prism-shaped unit cell fully modeled with fibers and a matrix including interlaminar areas is defined. For this quasi-isotropic laminate, a homogenization theory for nonlinear time-dependent composites with point-symmetric internal structures is applied, enabling us to analyze both the macroscopic and microscopic elastic-viscoplastic behaviors of the laminate. The substructure method is introduced into the theory to reduce computational costs. The present method is then applied to the elastic-viscoplastic analysis of a quasi-isotropic carbon fiber/epoxy laminate subjected to an in-plane uniaxial tensile load, to investigate the macroscopic elastic-viscoplastic behavior of the laminate and the microscopic stress and strain distributions in them.

Two-Scale Analysis of Thermal Behavior of CFRP Laminates Based on a Thermoelastoviscoplastic Homogenization Theory

2016 ◽  
Vol 725 ◽  
pp. 433-438
Author(s):  
Tetsuya Matsuda ◽  
Jin Toyomura ◽  
Tsubasa Ogaki ◽  
Masahiro Arai
Keyword(s):  
Carbon Fiber ◽  
Thermal Behavior ◽  
Homogenization Theory ◽  
Stress And Strain ◽  
Analysis Method ◽  
Cfrp Laminates ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
High Residual Stress ◽  
Carbon Fiber Epoxy

In this study, a two-scale thermoelastoviscoplastic analysis method for carbon fiber-reinforced plastic (CFRP) laminates is proposed based on a homogenization theory for time-dependent composites. For this, macroscopic and microscopic boundary value problems for CFRP laminates are derived to discuss the relation between the two problems. Using the relation, a two-scale thermoelastoviscoplastic analysis method is constructed, and then applied to the analysis of thermal behavior of an unsymmetric cross-ply carbon fiber/epoxy laminate. The laminate is subjected to a macroscopic temperature change from 180°C to 20°C. It is shown that quite high residual stress and strain occur both macroscopically and microscopically in the laminate, resulting in large macroscopic warpage of the laminate.

scholarly journals Implications of free-edge effect at thin plain-woven carbon fiber reinforced plastic laminates with out-of-plane waviness under cyclic loading

2021 ◽  
pp. 002199832110417
Author(s):  
Lukas Heinzlmeier ◽  
Stefan Sieberer ◽  
Christoph Kralovec ◽  
Martin Schagerl
Keyword(s):  
Carbon Fiber ◽  
Edge Effect ◽  
Fatigue Testing ◽  
Free Edge ◽  
Numerical Calculations ◽  
Carbon Fiber Reinforced Plastic ◽  
Damage Initiation ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Out Of Plane

The onset of damage caused by the free-edge effect in plain-woven carbon fiber reinforced plastic (CFRP) specimens with an out-of-plane waviness under tension-tension fatigue loading is investigated. Numerical calculations show that interlaminar and intralaminar stresses close to the out-of-plane waviness are higher than the equivalent stresses at the surrounding edge regions. Using submodels, the influence of the chosen out-of-plane waviness can be better assessed. The free-edge effect of the considered specimens, which originates from stress gradients between plies of different orientation, is altered by the change in the stress field caused by the out-of-plane waviness. Large interlaminar stresses between plies of the same orientation are obtained, which contrasts with existing literature. In experimental fatigue testing it is found that cracks at the free edge appeared at the predicted locations, and after reaching crack saturation, in regions close to the out-of-plane waviness, interlaminar and intralaminar stresses lead to additional cracks along the whole free edges. The experimental tests are supported by a three dimensional image correlation system (3D-DIC), a thermal-imager and a digital photographic camera, which allows detailed examination of selected areas. Visual observation during fatigue testing and post-mortem inspection show good agreement between experimental data and numerical calculations in relation to the location of the damage initiation. As a result, out-of-plane waviness at free edges must be considered as an additional significant fatigue damage initiation location in laminate analysis.

scholarly journals Damage Investigation of Carbon-Fiber-Reinforced Plastic Laminates with Fasteners Subjected to Lightning Current Components C and D

2020 ◽  
Vol 10 (6) ◽  
pp. 2147
Author(s):  
Jian Chen ◽  
Xiaolei Bi ◽  
Juan Liu ◽  
Zhengcai Fu
Keyword(s):  
Carbon Fiber ◽  
Current Amplitude ◽  
Carbon Fiber Reinforced Plastic ◽  
Conduction Current ◽  
Cfrp Laminate ◽  
Cfrp Laminates ◽  
Fiber Reinforced Plastic ◽  
Lightning Current ◽  
Reinforced Plastic ◽  
Component C

The damage induced by lightning strikes in carbon-fiber-reinforced plastic (CFRP) laminates with fasteners is a complex multiphysics coupling process. To clarify the effects of different lightning current components on the induced damage, components C and D were used in simulated lightning strike tests. Ultrasonic C-scans and stereomicroscopy were used to evaluate the damage in the tested specimens. In addition, the electrothermal coupling theory was adopted to model the different effects of the arc and the current flowing through the laminate (hereinafter referred to as the conduction current) on CFRP laminates with fasteners under different lightning current components. Component C, which has a low current amplitude and a long duration, ablated and gasified the fastener and caused less damage to the CFRP laminate. Under component C, the heat produced by the arc played a leading role in damage generation. Component D, which has a high current amplitude and a short duration, caused serious surface and internal damage in the CFRP laminate and little damage to the fastener. Under component D, the damage was mainly caused by the Joule heat generated by the conduction current.

Effects of Fiber Orientation Direction on Tool-Wear Processes in Down-Milling of Carbon Fiber-Reinforced Plastic Laminates

2015 ◽  
Vol 9 (4) ◽  
pp. 356-364 ◽  
Author(s):  
Satoru Maegawa ◽  
◽  
Yuta Morikawa ◽  
Shinya Hayakawa ◽  
Fumihiro Itoigawa ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Tool Wear ◽  
Fiber Orientation ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced ◽  
Cfrp Laminates ◽  
Fiber Reinforced Plastic ◽  
Orientation Direction ◽  
Reinforced Plastic ◽  
Carbon Fiber Reinforced

This paper discusses tool-wear processes in the milling of carbon fiber-reinforced plastic (CFRP) laminates. Plane down-milling tests with unidirectional and cross-directional CFRP laminates were performed using two types of cutting tools made of tungsten carbide and polycrystalline diamond. Measurements of the changes in the cutting forces and tool-wear widths over the cutting distance revealed that the fiber orientation direction in the CFRP laminates relative to the tool-traveling direction is an important parameter to determine the tool-wear processes. Additionally, based on obtained experimental results, a wear parameter to characterize cutting tool wear is introduced. This parameter can accurately explain the relationship between the worn tool-edge profiles and the processed-surface quality.

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