Assessment of Damage in a Unidirectional Off-axis Carbon-Epoxy Composite Under Cyclic Loading

2008 ◽  
pp. 336-336-13 ◽  
Author(s):  
LK Sorenser ◽  
A Plumtree
Keyword(s):  
Cyclic Loading ◽  
Epoxy Composite

Damage Characterization in Glass/Epoxy Composite Laminates under Normal and Oblique Planes of Cyclic Indentation Loading with AE Monitoring

2021 ◽  
Vol 79 (1) ◽  
pp. 61-77
Author(s):  
A Jayababu ◽  
V Arumugam ◽  
B Rajesh ◽  
C Suresh Kumar
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Cyclic Loading ◽  
Composite Laminates ◽  
Epoxy Composite ◽  
Damage Resistance ◽  
Damage Initiation ◽  
Residual Compressive Strength ◽  
Cyclic Indentation ◽  
Indentation Damage

This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.

scholarly journals Notch Tensile Strength of Carbon Fiber/Epoxy Composite Plate with a Center Hole under Static and Cyclic Loading

2019 ◽  
Vol 17 ◽  
pp. 292-299 ◽  
Author(s):  
Waleed H. Alhazmi ◽  
Amr A. Abd-Elhady ◽  
Saeed Mousa ◽  
M. Atta ◽  
A. Abu-Sinna ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Cyclic Loading ◽  
Composite Plate ◽  
Epoxy Composite ◽  
Notch Tensile Strength ◽  
Static And Cyclic Loading ◽  
Carbon Fiber Epoxy

scholarly journals Research of the endurance of epoxy composite materials under cyclic compression

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Boris Bondarev ◽  
Pavel Komarov ◽  
Anton Kosta ◽  
Oleg Korneev ◽  
Alexander Bondarev ◽  
...  
Keyword(s):  
Composite Materials ◽  
Cyclic Loading ◽  
Polymer Composite ◽  
Strain State ◽  
Epoxy Composite ◽  
Polymer Composite Materials ◽  
Careful Study ◽  
Stress Strain ◽  
Cyclic Action ◽  
Stress Strain State

The widespread use of polymer composite materials is largely constrained by the complexity of predicting the characteristics of their stress-strain state under cyclic types of loading. Due to the poor knowledge of the behavior of polymer composite materials under this kind of loading. At present, it is rather difficult to predict the durability of polymer composite materials under static types of loading, and the available methods for materials of a crystalline structure and polymers are not always applicable to them. Insufficient theoretical and experimental data on the assessment of the stress-strain state of polymer concretes under prolonged loading. Under long-term action of cyclic loads, changes in the structure of polymer composite materials occur due to local self-heating at the tops of growing submicrocracks and the associated change in the elastic-hesteretic properties of the material. In this case, the energy of fatigue manifests itself, when the simultaneous multifactorial cyclic action of natural and force stresses leads to an effect that exceeds the total action of certain types of stresses. And, if such processes have been sufficiently studied for wood, a natural polymer material, then for artificial conglomerates, such as polymer composites, these issues require careful study. Studies of the endurance of epoxy polymer concretes were carried out on samples of prisms 100x100x400 mm according to the method developed by the authors. The formula was used to determine the minimum number of samples required to build endurance lines. The value of the cycle asymmetry coefficient was taken equal to 0.6. The value of the maximum cyclic loading was taken from 0.62 Rв with a gradual decrease. The values of the endurance limit of an epoxy composite material under cyclic loading Rв,pul = 0.43 Rв or 93.72 MPa were obtained, which makes it possible to judge the sufficient durability of this material.

Damage Characterization in Glass/Epoxy Composite Laminates under Normal and Oblique Planes of Cyclic Indentation Loading with AE Monitoring

2021 ◽  
Vol 79 (1) ◽  
pp. 61-77
Author(s):  
A. Jayababu ◽  
V. Arumugam ◽  
B. Rajesh ◽  
C. Suresh Kumar
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Cyclic Loading ◽  
Composite Laminates ◽  
Epoxy Composite ◽  
Damage Resistance ◽  
Damage Initiation ◽  
Residual Compressive Strength ◽  
Cyclic Indentation ◽  
Indentation Damage

This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

Sign in / Sign up

Export Citation Format

Share Document