Property Degradation of Anisotropic Composite Laminates with Matrix Cracking. Part 2: Determination of Resolved Stiffness and Numerical Study of Stiffness Degradation

1997 ◽  
Vol 16 (5) ◽  
pp. 478-486 ◽  
Author(s):  
Hua Yu ◽  
Wang Xingguo ◽  
Li Zhengneng ◽  
He Qingzhi
Keyword(s):  
Composite Laminates ◽  
Numerical Study ◽  
Matrix Cracking ◽  
Stiffness Degradation ◽  
Anisotropic Composite

Numerical Investigation of a Stiffened Panel Subjected to Low Velocity Impacts

2015 ◽  
Vol 665 ◽  
pp. 277-280 ◽  
Author(s):  
Aniello Riccio ◽  
S. Saputo ◽  
A. Sellitto ◽  
A. Raimondo ◽  
R. Ricchiuto
Keyword(s):  
Numerical Investigation ◽  
Composite Laminates ◽  
Mechanical Response ◽  
Numerical Study ◽  
Fem Analysis ◽  
Matrix Cracking ◽  
Stiffened Panel ◽  
Low Velocity ◽  
Formation And Evolution ◽  
The Impact

The investigation of fiber-reinforced composite laminates mechanical response under impact loads can be very difficult due to simultaneous failure phenomena. Indeed, as a consequence of low velocity impacts, intra-laminar damage as fiber and matrix cracking and inter-laminar damage, such as delamination, often take place concurrently, leading to significant reductions in terms of strength and stability for composite structure. In this paper a numerical study is proposed which, by means of non-linear explicit FEM analysis, aims to completely characterize the composite reinforced laminates damage under low velocity impacts. The numerical investigation allowed to obtain an exhaustive insight on the different phases of the impact event considering the damage formation and evolution. Five different impact locations with the same impact energy are taken into account to investigate the influence on the onset and growth of damage.

Property Degradation of Anisotropic Composite Laminates with Matrix Cracking. Part 1: Development of Constitutive Relations for (θm/90n)s Cracked Laminates by Stiffness Partition

1996 ◽  
Vol 15 (11) ◽  
pp. 1149-1160 ◽  
Author(s):  
Hua Yu ◽  
Wang Xingguo ◽  
Li Zhengneng ◽  
He Qingzhi
Keyword(s):  
Composite Laminates ◽  
Constitutive Relations ◽  
Crack Density ◽  
Matrix Cracking ◽  
Normal Response ◽  
Shear Response ◽  
Plane Normal ◽  
Anisotropic Composite ◽  
Stiffness Partition

The study on property degradation of damaged composite laminates is extended to anisotropic laminates with matrix cracking. In Part 1 of the paper, an idea of “stiffness partition” is proposed to deal with the puzzle that the in-plane normal response is coupled with the shear response of the laminates. For (θ m/90 n), laminates containing transversely cracked layers under general in-plane loading, the constitutive relations are derived and the effective stiffnesses are expressed as the functions of crack density.

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.

The effect of multi-directional stiffness degradation on the non-linear analysis of composite laminates

2012 ◽  
Vol 19 (2) ◽  
pp. 127-137
Author(s):  
Sung-Cheon Han ◽  
Won-Hong Lee ◽  
Weon-Tae Park
Keyword(s):  
Composite Laminates ◽  
Composite Structures ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Shell Element ◽  
Linear Analysis ◽  
Matrix Cracking ◽  
Stiffness Degradation ◽  
Non Linear ◽  
Directional Stiffness

AbstractA formulation of element-based Lagrangian 9-node shell element based modified first-order shear deformation theory is improved for non-linear behaviors of composite laminates containing matrix cracking. Using the refined ANS (assumed natural strain) shell elements either show the optimum combination of sampling points with an excellent accuracy or remove the locking phenomenon. The multi-directional stiffness degradation caused by matrix cracking, which was proposed by Duan and Yao, is conducted. Natural coordinate based higher-order transverse shear strains are used in the present shell element. Numerical examples demonstrate that the present element behaves reasonably satisfactorily either for the linear or geometrical non-linear analysis of laminated composite structures. The results of laminated composite shells with matrix cracking may be the benchmark test for the non-linear analysis of damaged composite laminates.

Experimental investigation of the fatigue behavior of glass/epoxy composites evaluated by the stiffness degradation and damage accumulation

2018 ◽  
Vol 53 (6) ◽  
pp. 731-740 ◽  
Author(s):  
Walid Roundi ◽  
Abderrahim El Mahi ◽  
Abdellah El Gharad ◽  
Jean-Luc Rebiere
Keyword(s):  
Composite Laminates ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Matrix Cracking ◽  
Stiffness Degradation ◽  
Cyclic Behavior ◽  
Loading Level ◽  
Applied Loading ◽  
Number Of Cycles ◽  
Core Characteristics

The present paper deals with the mechanical behavior of glass/epoxy composite materials under static and cyclic tensile loading. The tested specimens have been made with different stacking sequences ([02/902]s; [902/02]s; [03/90]s; [903/0]s) according to the vacuum infusion procedure. The results of this investigation show the static behavior of the tested laminated composites characterized by the strain to failure, Young's modulus and tensile strength. Wöhler curves corresponding to each stacking sequence were plotted in order to observe the evolution of the maximum stress Smax according to the number of cycles. Fatigue Tests were performed under various applied loading levels ( r), and these values were chosen to evaluate the effect of loading level on the stiffness degradation and damage growth in the tested specimens. Afterward the evolution of the global damage factor ( D) according to the number of cycles was calculated in function of the core characteristics, applied loading level ( r) and type of loading. The cyclic behavior of the composite laminates mainly depends on the progressive developments of damage mechanisms such as matrix cracking, delamination, and fiber breakage.

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