Investigation of Mechanical Properties and Failure Behavior of CFRP Filament-Wound Composites Using an Acoustic Emission-Based Methodology and Numerical Simulation

Sajad Alimirzaei,Mehdi Ahmadi Najafabadi,Ali Nikbakht 한국섬유공학회 2023 Fibers and polymers Vol.24 No.2

Filament wound composites have a continuous structure, and to improve the mechanical behavior of these structures, it isnecessary to identify the damage mechanisms. The focus of this study is to investigate the mechanical properties and failureanalyses of filament-wound carbon/epoxy composite samples under three-point bending using the acoustic emission technique. To investigate this, first, using a filament winding machine, composite plates and composite structures with a squarecross section were fabricated. Afterward, composite specimens were tested and most independent elastic constants, strengthproperties, and shear properties were obtained. Then, a three-point bending testing of filament-wound composite specimenswas performed, and to identify the damage mechanisms the analysis of acoustic emission signals recorded during loadingwas also implemented. The acoustic emission signals of composite samples were classified using hierarchical and wavelettransform methods and the evolution of different damage mechanisms was investigated. Eventually, composite samples weresimulated in ABAQUS software, and to consider the damage mechanisms, the continuum damage mechanics model wasconsidered as a user material subroutine in simulation. The experimental results showed that the received acoustic emissionsignals matched very well with the mechanical behavior, and the acoustic response of the composite samples to the loadingincludes three regions. The amplitude range of the first, second, and third clusters was obtained between 35–74, 51–100, and55–84 dB, respectively. Finally, in the clustering method, the frequency range of fiber/matrix debonding and fiber breakagewere characterized between 200 and 250 and over 380 kHz, respectively.

Numerical investigation on the dynamic behaviors of turbine valve disc–seat impact at low velocity

Jianfeng Mao,Wei Zhe Wang,Junhui Zhang,Ying Zheng Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2

In this study, the dynamic behaviors on a valve seat subjected to the impact of the valve disc at low velocities were investigated by usingnumerical analysis with finite element method. The impact damage of the valve disc against seat was evaluated through a threedimensionaldynamic explicit calculation. The parameters considered in the simulations were impact velocity, disc obliquity, aspect ratio,and contact area ratio. The model for impact calculation was implemented in the code ABAQUS, which is based on the constitutiveequation and fracture strain equation of Johnson and Cook, as well as on continuum damage mechanics. The distribution of damagecaused by the impact was computed and discussed. The impact damage of the valve disc was minimized when the disc obliquity wasapproximately 40°. The effects of variation of selected design parameters on dynamic behaviors were discussed. The best design parameterswere proposed, which served as a guide for future valve design.

유한요소해석 후처리 기법을 이용한 용접부의 건전성 평가

이제명(JAE-MYUNG LEE),백점기(JEOM-KEE PAIK),강성원(SUNG-WON KANG),김명현(MYUNG-HYUN KIM) 한국해양공학회 2002 韓國海洋工學會誌 Vol.16 No.4

In this paper, a numerical methodology for health monitoring of weldment was proposed using finite element method coupled with continuum damage mechanics. The welding-induced residual stress distribution of T-joint weldment was calculated using a commercial finite element package SYSWELD+. The distribution of latent damage was evaluated from the stress and strain components taken as the output of a finite element calculation. Numerical examples were given to demonstrate the usefulness of this so-called "post-processing approach" in the case of welding-induced damage assessment.

A complete integrity assessment of welded connections under high and low cycle fatigue followed by fracture failure

Liuyang Feng,Tianyao Liu,Xudong Qian,Cheng Chen 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.4

This paper presents a comprehensive integrity assessment of welded structural components, including uniform highand low-cycle fatigue assessment of welded plate joints and fatigue-induced fracture assessment of welded plate joints. This study reports a series of fatigue and fracture tests of welded plate joints under three-point bending. To unify the assessment protocol for high- and low-cycle fatigue of welded plate joints, this study develops a numerical damage assessment framework for both high- and low-cycle fatigue. The calibrated damage material parameters are validated through the smooth coupon specimens. The proposed damage-based fatigue assessment approach describes, with reasonable accuracy, the total fatigue life of welded plate joints under high- and low-cycle fatigue actions. Subsequently, the study performs a tearing assessment on the ductile crack extension of the fatigue-induced crack. The tearing assessment diagram derives from the load-deformation curve of a single-edge notched bend, SE(B) specimen and successfully predicts the load-crack extension relation for the reported welded plate joints during the stable tearing process.

Homogenization based continuum damage mechanics model for monotonic and cyclic damage evolution in 3D composites

Jain, Jayesh R.,Ghosh, Somnath Techno-Press 2008 Interaction and multiscale mechanics Vol.1 No.2

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

ON THE TREATMENT OF DUCTILE FRACTURE BY THE LOCAL APPROACH CONCEPT IN CONTINUUM DAMAGE MECHANICS : THEORY AND EXAMPLE

Kim, Seoung-Jo,Kim, Jin-Hee,Kim, Wie-Dae 한국에너지학회 1996 Journal of Theoretical and Applied Mechanics Vol.2 No.1

In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.

Failure analysis of laminates by implementation of continuum damage mechanics in layer-wise finite element theory

B. Mohammadi,H. Hosseini-Toudeshky,M.H. Sadr-Lahidjani 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at +θ/-θ layers interfaces.

Failure analysis of laminates by implementation of continuum damage mechanics in layer-wise finite element theory

Mohammadi, B.,Hosseini-Toudeshky, H.,Sadr-Lahidjani, M.H. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.6

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at $+{\theta}/-{\theta}$ layers interfaces.

손상역학에 의한 섬유강화 복합재료의 피로수명 평가

임동민(Dong-min Lim),강기원(Ki-Weon Kang),김정규(Jung-Kyu Kim) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

With their fiber orientation and stacking sequence, composite laminates show quite anisotropy and their fatigue damage process is sequential occurrence of matrix cracking, delamination and fiber breakage. In the study, in order to propose model explaining these characteristics of composite laminates, fatigue analysis of composite laminates that introduced into damage mechanics, are performed. The average stress is disassembled with stress components of matrix, fiber and interlaminar interface through stress analysis. Each stress components are used to assess static damage analysis based on continuum damage mechanics (C.D.M.). Fatigue damage curves are obtained from hysteresis loop and assessed by the fatigue damage analysis. Then, static and fatigue damage analysis are combined. Expected results such as stress-cycle relation are verified by the experimental results of fatigue tests.

연속체 손상역학을 이용한 용접구조물의 수치피로시험기법

이치승,김영환,김태우,유병문,이제명,Lee, Chi-Seung,Kim, Young-Hwan,Kim, Tae-Woo,Yoo, Byung-Moon,Lee, Jae-Myung 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.3

Fatigue life evaluation of welded structures in a range of high cycles is one of the most difficult problems since extremely small plastic deformation and damage occur during the loading cycles. Moreover, it is very difficult to identify the strong non-linearities of welding, inducing residual stress. In this paper, numerical fatigue test method for welded structures was developed using continuum damage mechanics with inherent strain. Recently, continuum damage mechanics, which can simulate both crack initiation at the micro-scale level and crack propagation at the meso-scale level, has been adopted in the fracture related problem. In order to consider the residual stresses in the welded strictures, damage calculation in conjunction with welding, inducing inherent strain, was proposed. The numerical results obtained from the damage calculation were compared to experimental results.