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Linear Elastic Fracture Mechanics (LEFM)-Based Single Lap Joint (SLJ) Mixed-Mode Analysis for Aerospace Structures

  • B. K. MaheshaEmail author
  • D. Thulasi Durai
  • D. Karuppannan
  • K. Dilip Kumar
Conference paper
  • 924 Downloads
Part of the Lecture Notes in Mechanical Engineering book series (LNME)

Abstract

This paper investigates the study of crack propagation on single lap joint (SLJ) using cohesive zone modeling (CZM) for aerospace applications. To carry out the above task, linear elastic fracture mechanics (LEFM) approach using finite element methods was used to study the damage propagation in adhesively bonded joints. A traction–separation law was used to simulate the mode-II and mixed-mode-I+II interfacial fractures of adhesively bonded specimens loaded (quasi-static) in three-point bending and mixed-mode bending. An initial crack opening was introduced at the interfaces of the adherend/adhesive. The boundary conditions for SLJ have been set to carry out the interlaminar mode-II (shear mode) and mixed-mode fracture analysis by end notched flexure (ENF) and mixed-mode bending (MMB) methods. Optimized cohesive parameters from the literature survey were used for simulation of the tests, and same parameters have been validated to continue the research work focusing mainly on progressive delamination in SLJ. The total displacement of 10 mm was applied at free end, and as a result the reaction forces at fixed end steadily progressed up to 60% of applied displacement; further it has been observed the model starts failing by reduction in load versus displacement slope curve.

Keywords

Crack Linear elastic fracture mechanics Cohesive zone modeling Mode-II fracture toughness Mixed-mode analysis 

Nomenclature

SLJ

Single lap joint

LEFM

Linear elastic fracture mechanics

SERR

Strain energy release rate

CZM

Cohesive zone model

ENF

End notched flexture

MMB

Mixed-mode bending

GC

Critical strain energy release rate/fracture toughness

GT

Total strain energy release rate

GIC

Fracture toughness in pure mode-I direction

GIIC, GIIIC

Fracture toughness in pure mode-II and mode-III direction

η

Exponent in B–K law

KNN, KSS and KTT

Elastic parameters for traction–separation law in the normal direction and the two shear directions

Nmax, Smax, Tmax

Maximum stresses for traction–separation law in the normal direction and the two shear directions

Lc

Characteristic length of the cohesive element

ao

Initial crack length

δ

Delamination length

tply

Cured ply thickness

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • B. K. Mahesha
    • 1
    Email author
  • D. Thulasi Durai
    • 2
  • D. Karuppannan
    • 3
  • K. Dilip Kumar
    • 1
  1. 1.NMAM Institute of TechnologyNitteIndia
  2. 2.CSMST, CSIR-NALBangaloreIndia
  3. 3.ACD, CSIR-NALBangaloreIndia

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