Evolution of matrix cracking in cross-ply CFRP laminates: Differences between mechanical and thermal loadings

2021 ◽  
pp. 69-76
Author(s):  
C. Henaff-Gardin ◽  
I. Goupillaud ◽  
M.C. Lafarie-Frenot
Keyword(s):  
Matrix Cracking ◽  
Cfrp Laminates

scholarly journals Measurement of residual strains as a parameter of matrix cracking in CFRP laminates

2021 ◽  
Vol 15 (4) ◽  
pp. JAMDSM0040-JAMDSM0040
Author(s):  
M. J. Mohammad FIKRY ◽  
Shinji OGIHARA ◽  
Vladimir VINOGRADOV
Keyword(s):  
Matrix Cracking ◽  
Cfrp Laminates ◽  
Residual Strains

Measurement of Residual Strains As a Parameter of Matrix Cracking in CFRP Laminates

2020 ◽  
Author(s):  
M. J. Mohammad Fikry ◽  
Shinji Ogihara ◽  
Vladimir Vinogradov
Keyword(s):  
Viscoelastic Behavior ◽  
Matrix Cracking ◽  
Time Dependent ◽  
Strain Gauges ◽  
Recovery Test ◽  
Cfrp Laminates ◽  
Matrix Cracks ◽  
Theoretical Predictions ◽  
Residual Strains ◽  
Good Agreement

Abstract Matrix cracking in CFRP laminates results in degradation of mechanical properties of the material and appearance of residual strains. In this study, the residual strains investigated are experimentally and analytically for CFRP [0/756]s laminates. The strain gauges were used in this study to measure the strains. Due to very small residual strains at the unloading condition, the residual strains were also measured at different stress levels for laminates with different crack densities and are compared with theoretical predictions. Time-dependent viscoelastic behavior of the material is also considered to accurately measure the residual strains due to the occurrence of matrix cracks. This was done by using the strain recovery test when the loads were stopped for 1–1.5 hours during unloading and the strain changes during these times were recorded. The experimental results of the residual strains are in reasonably good agreement with the theoretical predictions. The fiber non-linearity properties of the laminates may cause some experimental data to shift above the analytical line.

scholarly journals Damage Propagation Analysis in the Single Lap Shear and Single Lap Shear-Riveted CFRP Joints by Acoustic Emission and Pattern Recognition Approach

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3963
Author(s):  
Claudia Barile ◽  
Caterina Casavola ◽  
Giovanni Pappalettera ◽  
Paramsamy Kannan Vimalathithan
Keyword(s):  
Pattern Recognition ◽  
Acoustic Emission ◽  
Research Work ◽  
Amplitude Distribution ◽  
Acoustic Energy ◽  
Matrix Cracking ◽  
Cumulative Energy ◽  
Cfrp Laminates ◽  
Hybrid Joint ◽  
Lap Shear

An innovative way of using the Acoustic Emission (AE) technique is introduced in this research work. The ratio of recorded acoustic energy and the counts recorded for each acoustic event were used for characterizing Carbon Fiber Reinforced Plastic (CFRP) laminates adhesively bonded with and without mechanical fasteners. The cumulative counts and cumulative energy of the recorded acoustic events were used for identifying the critical points of failure under loading of these hybrid joint specimens. The peak amplitude distribution was used for identifying the different damage modes such as delamination, matrix cracking and fiber breakage, albeit, ineffectively. The new parameter energy per count was introduced in this work, which can successfully identify the different damage modes under loading. To differentiate the damage modes using the energy per count, they were clustered using k-means++ pattern recognition technique. The method introduced in this work can estimate the damage modes of the CFRP specimens.

Experimental Characterization of Matrix Cracking Behavior in Thermally Cycled CFRP Laminates

2002 ◽  
Vol 11 (3) ◽  
pp. 287-305 ◽  
Author(s):  
Shinji Ogihara ◽  
Akira Kobayashi ◽  
Takamoto Ishiguro ◽  
Nobuo Otani
Keyword(s):  
Thermal Cycling ◽  
Crack Density ◽  
Tensile Loading ◽  
Matrix Crack ◽  
Matrix Cracking ◽  
Thermal Cycles ◽  
Critical Energy Release Rate ◽  
Cracking Behavior ◽  
Cfrp Laminates ◽  
The Matrix

The effect of thermal cycling on the mechanical properties of composite materials is an important issue in engineering, especially in their applications to the space environment. The present study concerned with the experimental study of both the thermal cycling induced matrix cracking and the effect of thermal cycling on the matrix cracking behavior under tensile loading in CFRP laminates. Two kinds of carbon/epoxy systems, T800H/3631 and T300/2500, are used for the laminate configurations of (0/90)s and (90/0)s. The specimens are thermally cycled between −196 and 100°C. Thermal cycling tests are performed up to 1000 cycles. The polished edge surfaces of specimens are examined by the replica technique, and then the matrix crack density is measured as a function of the number of thermal cycles. It is found that the first matrix cracking in (0/90)s and (90/0)s laminates occurs at almost the same numbers of thermal cycles. It is also found that the matrix crack density increases more rapidly in (0/90)s laminates than in (90/0)s laminates in both material systems. To investigate the effect of thermal cycling on matrix cracking behavior under tensile loading, a series of tensile tests on thermally cycled specimens are performed. The effect of thermal cycling on matrix cracking under tension is evaluated in terms of the change in the critical energy release rate and the critical stress for matrix cracking.

Measurement of Residual Strains as a Parameter of Matrix Cracking in Cfrp Laminates

2021 ◽  
Author(s):  
M. Fikry Jelani ◽  
Shinji Ogihara ◽  
Vladimir Vinogradov
Keyword(s):  
Matrix Cracking ◽  
Cfrp Laminates ◽  
Residual Strains

Matrix Crack Detection of CFRP Laminates in Cryogenic Temperature Using Electrical Resistance Change Method

2006 ◽  
Vol 321-323 ◽  
pp. 873-876 ◽  
Author(s):  
Akira Todoroki ◽  
Kazuomi Omagari ◽  
Masahito Ueda
Keyword(s):  
Electrical Resistance ◽  
Cryogenic Temperature ◽  
Matrix Crack ◽  
Fuel Tank ◽  
Matrix Cracking ◽  
Resistance Change ◽  
Cfrp Laminates ◽  
Resistance Increase ◽  
Matrix Cracks ◽  
Electrical Resistance Change

For a cryogenic fuel tank of a next generation rocket, a Carbon Fiber Reinforced Plastic (CFRP) laminated composite tank is one of the key technologies. For the fuel tank made from the laminated composites, matrix cracks are significant problems that cause leak of the fuel. In the present paper, electrical resistance change method is adopted to monitor the matrix cracking of the CFRP laminate. Previous studies show that tension load in fiber direction causes electrical resistance increase due to the piezoresistivity of the carbon fibers, and fiber breakages also cause the electrical resistance increase of the CFRP laminates. In order to distinguish the electrical resistance changes due to matrix cracking from those due to the piezoresistivity and the fiber breakages, residual electrical resistance change under the complete unloading condition is employed in the present study. Experimental investigations were performed using cross-ply laminates in cryogenic temperature. As a result, it can be revealed that the residual electrical resistance change is a useful indicator for matrix crack monitoring of the cross-ply CFRP laminates.

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