NUMERICAL PREDICTION OF STIFFNESS DEGRADATION OF THIN-PLY CFRP LAMINATES UNDER FATIGUE LOADING

2021 ◽  
Author(s):  
RYOMA AOKI ◽  
RYO HIGUCHI ◽  
TOMOHIRO YOKOZEKI
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Crack Density ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Stiffness Degradation ◽  
Cfrp Laminates ◽  
Mechanics Model ◽  
Element Simulation ◽  
Proposed Model

This study aims to conduct a fatigue simulation for predicting the stiffness degradation of thin-ply composite laminates with several ply thicknesses. For the simulation, a fatigue evolution model of intra-laminar damage in thin-ply composite laminates considering the effect of ply thickness was proposed. The intra-laminar damage evolution was modeled using the continuum damage mechanics model and the static and fatigue evolution law were formulated by relating the transverse crack density to the damage variable. The finite element simulation using the proposed model was conducted to predict the stiffness degradation of the laminates as a function of the number of loading cycles. The simulation results show that the experimental data can be reproduced by using the proposed fatigue model.

Study on Continuum Damage Mechanics Model for High Cycle Fatigue

2016 ◽  
Vol 835 ◽  
pp. 564-567
Author(s):  
Xin Tong Shi ◽  
Ying Chun Xiao ◽  
Hong Chen ◽  
Bo Huang
Keyword(s):  
Experimental Data ◽  
Damage Mechanics ◽  
High Cycle Fatigue ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Continuum Damage ◽  
Cycle Fatigue ◽  
Stress Effects ◽  
Mechanics Model ◽  
Proposed Model

A continuum damage mechanics model was proposed to predict the high cycle fatigue life. In order to consider mean stress effects, the Walker correction was introduced in proposed model. The model was verified by experimental data on LC4 and LY12CZ aluminum alloy under high cycle fatigue loading. The results showed that the predicted life of proposed model well correlated with experimental data.

Material orthotropy effects on progressive damage analysis of open-hole composite laminates under tension

2017 ◽  
Vol 36 (20) ◽  
pp. 1473-1486 ◽  
Author(s):  
Song Zhou ◽  
Yi Sun ◽  
Boyang Chen ◽  
Tong-Earn Tay
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Tensile Loading ◽  
Progressive Damage ◽  
Cohesive Elements ◽  
Damage Initiation ◽  
Proposed Model ◽  
Open Hole

The sizes effects on the strengths of open-hole fibre-reinforced composite laminates subjected to tensile loading (OHT) have been investigated widely. However, little attention has been paid to the influence of material orthotropy. This paper presents a progressive damage model for the model failure of notched laminates under tensile loading based on continuum damage mechanics and cohesive elements. The effects of orthotropy on the failure of notched laminates with seven different ply sequences are investigated by our proposed model. The prediction results adopting the Hoffman and Pinho failure criterions to determine matrix damage initiation are compared with the results of experiments. Our proposed models are able to predict the strong influence of orthotropy on strengths of open-hole laminate under tension, and model using Pinho criterion can predict the open-hole tension strength most accurately.

Development of a Synergistic Damage Mechanics-Based Model for Predicting Multiaxial Effects in Progressive Failure of Composite Structures

2014 ◽  
Author(s):  
John Montesano ◽  
Chandra Veer Singh
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Damage Mechanics ◽  
Progressive Failure ◽  
Continuum Damage Mechanics ◽  
Fatigue Loading ◽  
Progressive Damage ◽  
Progressive Failure Analysis ◽  
Fiber Reinforced Polymer Composites ◽  
Stress States

A major benefit of advanced fiber-reinforced polymer composites is that they can be tailored and optimized to suit a particular structural application by orienting the reinforcing fibers along multiple directions. For practical load-bearing structural components manufactured from multidirectional laminates, predicting their mechanical behaviour is quite complex. This is specifically the case for progressive failure analysis of these materials when subjected to quasi-static or fatigue loading since local cracks will initiate and evolve in multiple directions simultaneously. The difficulty of the problem increases further when these laminates are subjected to complex multiaxial stress states. This is due to the fact that the multidirectional crack state will be subjected to additional crack driving stress components, which will ultimately alter the crack evolution characteristics. A synergistic damage mechanics (SDM) methodology has recently been developed to address these issues in progressive damage analyses of composite laminates containing multiple damage modes and subjected to uniaxial loading [1]. By combining micromechanics and continuum damage mechanics, the SDM methodology provides a rigorous and practical tool for accurate prediction of progressive damage behaviour in composite structures. This is essential for accurately predicting the integrity and durability of practical structures, which will lead to safer and more efficient designs.

scholarly journals Continuum damage mechanics modeling of composite laminates including transverse cracks

2017 ◽  
Vol 27 (6) ◽  
pp. 877-895 ◽  
Author(s):  
Tomonaga Okabe ◽  
Sota Onodera ◽  
Yuta Kumagai ◽  
Yoshiko Nagumo
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Elastic Moduli ◽  
Crack Density ◽  
Continuum Damage Mechanics ◽  
Damage Variable ◽  
Continuum Damage ◽  
Transverse Cracks ◽  
Element Analysis ◽  
The Finite Element Analysis

In this study, the continuum damage mechanics model for predicting the stiffness reduction of composite laminates including transverse cracks is formulated as a function of crack density. To formulate the model, first the damage variable in the direction normal to the fiber of a ply including transverse cracks is derived. The damage variable is derived by the model assuming a plane strain field in the isotropic plane and using the Gudmundson–Zang model for comparison. The effective compliance based on the strain equivalent principle proposed by Murakami et al. and classical laminate theory are then used to formulate the elastic moduli of laminates of arbitrary lay-up configurations as a function of the damage variable. Finally, the results obtained from this model are compared to the finite-element analysis reported in previous studies. The model proposed in this paper can predict the stiffness of laminates containing damage due to transverse cracks (or surface crack) from just the mechanical properties of a ply and the lay-up configurations. Furthermore, this model can precisely predict the finite-element analysis results and experiment results for the elastic moduli of the laminate of arbitrary lay-up configuration, such as cross-ply, angle ply, and quasi-isotropic, including transverse cracks. This model only considers the damage of the transverse crack; it does not consider damage such as delamination. However, this model seems to be effective in the early stage of damage formation when transverse cracking mainly occurs. The model assuming plane strain field in the isotropic plane which is proposed in this paper can calculate the local stress distribution in a ply including transverse cracks as a function of crack density. The damage evolution of transverse cracks can thus be simulated by determining the fracture criterion.

scholarly journals Damage in Fibreglass Composite Laminates Used for Pipes

2018 ◽  
Vol 774 ◽  
pp. 155-160 ◽  
Author(s):  
Juan S.B. León ◽  
Octavio Andrés González-Estrada ◽  
Alberto Pertuz
Keyword(s):  
Composite Laminates ◽  
Damage Mechanics ◽  
Hoop Stress ◽  
Stress Ratio ◽  
Continuum Damage Mechanics ◽  
Element Analysis ◽  
Gas Industry ◽  
Damage Initiation ◽  
Mechanics Model ◽  
Initiation And Propagation

In this work, we present a model for the initiation and evolution of damage for a composite fibre-reinforced pipe used in the Oil & Gas industry, based on a commercially available pipe. A continuum damage mechanics model was employed to determine the initiation and evolution of damage. This model was implemented using finite element analysis to investigate the performance of the commercial composite pipe. Initially, the material properties were obtained from experimental data and fitting with static structural simulations. Then, FE simulations with damage were performed, considering three different boundary conditions: open, closed (pressure-vessel type) and fixed ends, the load considered was internal pressure. Results showed differences not only in the stress distribution but on the damage initiation and evolution along the geometry of the pipe. These differences in the damage initiation and propagation can be explained as the result of different axial-hoop stress ratio.

Micromechanical prediction of damage due to transverse ply cracking under fatigue loading in composite laminates

2017 ◽  
Vol 36 (5) ◽  
pp. 377-395 ◽  
Author(s):  
Bjian Mohammadi ◽  
Milad Rohanifar ◽  
Davood Salimi-Majd ◽  
Amin Farrokhabadi
Keyword(s):  
Experimental Data ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Crack Density ◽  
Strain Energy Release ◽  
Fatigue Loading ◽  
Matrix Cracking ◽  
Finite Element Software ◽  
Stiffness Reduction ◽  
The Matrix

To predict the matrix microcracking of laminated composites under fatigue loading, a novel energy based model is presented in the framework of micromechanics. For this purpose, strain energy release rate (SERR) of microcracks which had been derived previously for the whole laminate, is developed for a lamina, and then is calculated using a stress transfer-based stiffness reduction method. The advantages of the proposed method include its capability to predict the matrix cracking of general lay-ups based on the local stresses and stiffnesses of each plies separately and not being limited to a special stacking sequence. In order to predict micro-cracking propagation of composites under cyclic loading, the coefficients of the modified Paris law are extracted using the available experimental data of crack density–cycle curves. Then using multi-scale modelling and continuum damage mechanics concept, the proposed algorithm is implemented in ANSYS finite element software, as a new user defined material (Usermat). The static progress of failure on [45/−45]s laminate is simulated and the obtained results are compared with the existing experimental data in a good agreement. Finally, the results of implemented fatigue algorithm for different cross-ply laminates under different stress levels are obtained and compared with the available experimental data.

Fatigue Life of the Human Teeth: A Continuum Damage Approach

2019 ◽  
Vol 43 ◽  
pp. 1-19
Author(s):  
Theddeus Tochukwu Akano
Keyword(s):  
Fatigue Life ◽  
Damage Mechanics ◽  
Stress Amplitude ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Elastoplastic Model ◽  
Human Teeth ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Cycles To Failure

Normal oral food ingestion processes such as mastication would not have been possible without the teeth. The human teeth are subjected to many cyclic loadings per day. This, in turn, exerts forces on the teeth just like an engineering material undergoing the same cyclic loading. Over a period, there will be the creation of microcracks on the teeth that might not be visible ab initio. The constant formation of these microcracks weakens the teeth structure and foundation that result in its fracture. Therefore, the need to predict the fatigue life for human teeth is essential. In this paper, a continuum damage mechanics (CDM) based model is employed to evaluate the fatigue life of the human teeth. The material characteristic of the teeth is captured within the framework of the elastoplastic model. By applying the damage evolution equivalence, a mathematical formula is developed that describes the fatigue life in terms of the stress amplitude. Existing experimental data served as a guide as to the completeness of the proposed model. Results as a function of age and tubule orientation are presented. The outcomes produced by the current study have substantial agreement with the experimental results when plotted on the same axes. There is a notable difference in the number of cycles to failure as the tubule orientation increases. It is also revealed that the developed model could forecast for any tubule orientation and be adopted for both young and old teeth.

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