scholarly journals Open holes in composite laminates with finite dimensions: structural assessment by analytical methods

2022 ◽  
Author(s):  
M. Nguyen-Hoang ◽  
W. Becker
Keyword(s):  
Failure Analysis ◽  
Analytical Methods ◽  
Composite Laminates ◽  
Design Feature ◽  
Potential Method ◽  
Finite Width ◽  
Efficient Computation ◽  
Stress Concentrations ◽  
Open Hole ◽  
Circular Holes

AbstractOpen circular holes are an important design feature, for instance in bolted joint connections. However, stress concentrations arise whose magnitude depends on the material anisotropy and on the defect size relative to the outer finite plate dimensions. To design both safe and light-weight optimal structures, precise means for the assessment are crucial. These can be based on analytical methods providing efficient computation. For this purpose, the focus of the present paper is to provide a comprehensive stress and failure analysis framework based on analytical methods, which is also suitable for use in industry contexts. The stress field for the orthotropic finite-width open-hole problem under uniform tension is derived using the complex potential method. The results are eventually validated against Finite-Element analyses revealing excellent agreement. Then, a failure analysis to predict brittle crack initiation is conducted by means of the Theory of Critical Distances and Finite Fracture Mechanics. These failure concepts of different modelling complexity are compared to each other and validated against experimental data. The size effect is captured, and in this context, the influence of finite width on the effective failure load reduction is investigated.

scholarly journals Progressive Failure Analysis in Open-Hole Tensile Composite Laminates of Airplane Stringers Based on Tests and Simulations

2020 ◽  
Vol 11 (1) ◽  
pp. 185
Author(s):  
Jian Shi ◽  
Mingbo Tong ◽  
Chuwei Zhou ◽  
Congjie Ye ◽  
Xindong Wang
Keyword(s):  
Failure Analysis ◽  
Composite Laminates ◽  
Progressive Failure ◽  
Tensile Load ◽  
Fiber Failure ◽  
Stress Criterion ◽  
Progressive Failure Analysis ◽  
Analysis Technique ◽  
Open Hole ◽  
Failure Types

The failure types and ultimate loads for eight carbon-epoxy laminate specimens with a central circular hole subjected to tensile load were tested experimentally and simulated using two different progressive failure analysis (PFA) methodologies. The first model used a lamina level modeling based on the Hashin criterion and the Camanho stiffness degradation theory to predict the damage of the fiber and matrix. The second model implemented a micromechanical analysis technique coined the generalized method of cells (GMC), where the 3D Tsai–Hill failure criterion was used to govern matrix failure, and the fiber failure was dictated by the maximum stress criterion. The progressive failure methodology was implemented using the UMAT subroutine within the ABAQUS/implicit solver. Results of load versus displacement and failure types from the two different models were compared against experimental data for the open hole laminates subjected to tensile displacement load. The results obtained from the numerical simulation and experiments showed good agreement. Failure paths and accurate damage contours for the tested specimens were also predicted.

The Influence of Non-Traditional Composite Laminates on Open-Hole Tension Strength

2007 ◽  
Author(s):  
D. P. Stone ◽  
L. V. Smith ◽  
A. Kothidar
Keyword(s):  
Strain Field ◽  
Composite Laminates ◽  
Damage Evolution ◽  
Adhesive Bonding ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Strain Measurements ◽  
Stress Risers ◽  
Open Hole ◽  
Increased Strength

Composite materials are commonly used in applications with a need for increased strength or reduced weight. The composite structure is often attached using mechanical fasteners, even in cases where adhesive bonding is prevalent. The strength of the composite is typically reduced by large factors in the presence of these stress risers. The following considers the sensitivity of non-traditional layups to stress concentrations in the form of open-hole tension. The effects are described numerically and experimentally using finite element analysis and spatial strain measurements, respectively. Improvements in strength exceeding 10% from this preliminary exercise suggest that tailoring fiber orientations may have potential to minimize the effect of stress concentrations. Consideration of the strain field in the vicinity of the hole showed evidence of damage evolution within approximately 25% UTS for many of the laminates. The maximum strain failure criterion was able to describe the onset of damage or yield for the laminates considered here.

Stress-Concentration Factors Around a Central Circular Hole in a Plate Loaded Through Pin in the Hole

1940 ◽  
Vol 7 (1) ◽  
pp. A5-A9 ◽  
Author(s):  
M. M. Frocht ◽  
H. N. Hill
Keyword(s):  
Stress Concentration ◽  
Hole Diameter ◽  
Finite Width ◽  
Center Line ◽  
Strain Gages ◽  
Stress Concentrations ◽  
Circular Holes ◽  
Concentration Factors ◽  
Institute Of Technology ◽  
Stress Concentration Factors

Abstract This paper deals with factors of stress concentrations in plates of finite width with central circular holes loaded through pins or rivets. Two sets of results are presented, one from oversize aluminum specimens in which the stresses were determined from strain-gage measurements, the other, from photoelastic tests with small bakelite models. The two investigations were conceived and executed independently. The tests involving the use of strain gages were made at Aluminum Research Laboratories and the photoelastic tests were made at the Photoelastic Laboratory of the Carnegie Institute of Technology. While most of the tests involved plates loaded through a single pin in a hole on the longitudinal center line of the plate, several tests were made on plates loaded through two pins symmetrically situated about the center line of the plate. Numerical values for the stress-concentration factor k are given for ratios of hole diameter to width of plate (2r/D) ranging from 0.086 to 0.76.

Progressive fracture analysis of the open-hole composite laminates: experiment and simulation

2021 ◽  
Vol 262 ◽  
pp. 113628
Author(s):  
Zhaoyang Ma ◽  
Jianlin Chen ◽  
Qingda Yang ◽  
Zheng Li ◽  
Xianyue Su
Keyword(s):  
Composite Laminates ◽  
Fracture Analysis ◽  
Open Hole ◽  
Progressive Fracture ◽  
Experiment And Simulation

Some Unexpected Results in the Stress Calculation Around Multiple Holes in an Isotropic Plate Under In-Plane-Loads

2014 ◽  
Author(s):  
Ghazi H. Asmar ◽  
Elie A. Chakar ◽  
Toni G. Jabbour
Keyword(s):  
Finite Element ◽  
Isotropic Plate ◽  
Potential Method ◽  
The Finite Element Method ◽  
Close Proximity ◽  
Complex Fourier Series ◽  
Circular Holes ◽  
Complex Potential Method ◽  
Multiple Holes

The Schwarz alternating method, along with Muskhelishvili’s complex potential method, is used to calculate the stresses around non-intersecting circular holes in an infinite isotropic plate subjected to in-plane loads at infinity. The holes may have any size and may be disposed in any manner in the plate, and the loading may be in any direction. Complex Fourier series, whose coefficients are calculated using numerical integration, are incorporated within a Mathematica program for the determination of the tangential stress around any of the holes. The stress values obtained are then compared to published results in the literature and to results obtained using the finite element method. It is found that part of the results generated by the authors do not agree with some of the published ones, specifically, those pertaining to the locations and magnitudes of certain maximum stresses occurring around the contour of holes in a plate containing two holes at close proximity to each other. This is despite the fact that the results from the present authors’ procedure have been verified several times by finite element calculations. The object of this paper is to present and discuss the results calculated using the authors’ method and to underline the discrepancy mentioned above.

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