scholarly journals Post-Impact Behaviour of Pseudo-Ductile Thin-Ply Angle-Ply Hybrid Composites

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 579 ◽  
Author(s):  
Alessia Prato ◽  
Marco Longana ◽  
Ambreen Hussain ◽  
Michael Wisnom
Keyword(s):  
Strain Distribution ◽  
Hybrid Composites ◽  
Tensile Load ◽  
Tensile Loading ◽  
Tensile Tests ◽  
Image Correlation ◽  
Impact Behaviour ◽  
Damage Propagation ◽  
Post Impact ◽  
Non Destructive

This work experimentally explores the post-impact behaviour of thin-ply angle-ply pseudo-ductile carbon fibre laminates subjected to tensile load. Indentation and low-speed impact tests were performed on standard tensile test specimens. Non-destructive tests were used to investigate the damage propagation. Digital Image Correlation (DIC) was adopted to detect the strain distribution during tensile tests. Post-damage pseudo-ductile behaviour was retained in angle-ply hybrid composites subjected to tensile loading conditions.

scholarly journals An Experimental and Numerical Investigation to Characterize an Aerospace Composite Material with Open-Hole Using Non-Destructive Techniques

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4148 ◽  
Author(s):  
Norberto Feito ◽  
José Vicente Calvo ◽  
Ricardo Belda ◽  
Eugenio Giner
Keyword(s):  
Strain Distribution ◽  
Stress Concentrator ◽  
Image Correlation ◽  
Fiber Waviness ◽  
Static Tests ◽  
Manufacturing Defects ◽  
Open Hole ◽  
Static Tensile ◽  
Non Destructive ◽  
Non Destructive Techniques

In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze the behavior of this material. We aim at characterizing the influence of the manufacturing defects and the stress concentrator through the temperature variation and strain distribution during fatigue and quasi-static tests. On the one hand, the fatigue specimens were tested in two main perpendicular directions of the laminate. The results revealed that manufacturing defects such as fiber waviness can have a major impact than open-hole stress concentrator on raising the material temperature and causing fracture. In addition, the number of plies with fibers oriented in the load direction can drastically reduce the temperature increment in the laminate. On the other hand, the quasi-static tensile tests showed that the strain distribution around the hole is able to predict the crack initiation and progression in the external plies. Finally, the experimental quasi-static tests were numerically simulated using the finite element method showing good agreement between the numerical and experimental results.

Cluster analysis of acoustic emission signals and tensile properties of carbon/glass fiber–reinforced hybrid composites

2019 ◽  
Vol 18 (5-6) ◽  
pp. 1686-1697 ◽  
Author(s):  
Wen-zheng Zhao ◽  
Wei Zhou
Keyword(s):  
Acoustic Emission ◽  
Digital Image Correlation ◽  
Glass Fiber ◽  
Digital Image ◽  
Hybrid Composites ◽  
Correlation Method ◽  
Tensile Loading ◽  
Image Correlation ◽  
Matrix Cracking ◽  
Woven Composites

Understanding the damage and failure of carbon/glass epoxy hybrid woven composites under tensile loading based on acoustic emission signals is a challenging task in their practical uses. In this study, an approach based on fuzzy c-means algorithm is proposed to process the acoustic emission signals from tensile loading of composites monitored by combining acoustic emission technology and digital image correlation method. The results show that the acoustic emission signals from tensile loading can be divided into three clusters. The three clusters correspond to three kinds of damage modes including matrix cracking, fiber/matrix debonding, delamination, and fiber breakage. By comparing the acoustic characteristics of these classes, a correlation procedure between the clusters and the damage mechanisms observed is proposed. Meanwhile, it can be found that debonding and fiber break signals for glass fiber correspond to a lower frequency range than that for carbon fiber. Moreover, the method combining acoustic emission and digital image correlation can effectively monitor the damage process of the specimen both on the inside and outside, which can provide a reference for the health monitoring of composite structure.

Necking phenomenon based on the Aramis system

2018 ◽  
Vol 233 (11) ◽  
pp. 3904-3916 ◽  
Author(s):  
Shier Dong ◽  
Anjiang Xian ◽  
Zhanghua Lian ◽  
Hazem Samih Mohamed ◽  
Hongyu Ren
Keyword(s):  
Distribution Function ◽  
Strain Distribution ◽  
Axial Strain ◽  
Three Dimensional ◽  
Correlation Method ◽  
Tensile Tests ◽  
Image Correlation ◽  
Calculation Error ◽  
Strain Calculation ◽  
Deformation Properties

In this study, the necking three-dimensional strain on minimum cross-section at room temperature was performed experimentally and analytically. A modified strain assumption was applied to overcome significant errors in calculating necking strain by Bridgman assumption. Then, one relatively simple strain distribution function was deduced based on equilibrium equation of necking element. To obtain the parameters in this function, the monotonic tensile tests in two kinds of carbon structure steels Q235 and Q345 were carried out. Meanwhile, the Aramis system based on digital image correlation method was adopted to measure the surface axial strain and deformation parameters during the loading process. The experimental and numerical results were compared with the traditional Bridgman strain assumption. The maximum axial strain calculation error the strain distribution function and experiment value was less than 8%, which was obviously less than that calculated by Bridgman assumption. Additionally, the variation law of the three-dimensional strain calculated by this function was consistent with that obtained by the macroscopic analysis of fracture surface. The application of traditional Bridgman formula can be expanded by this study. Meanwhile, it can provide a new idea to study the stress distribution characteristics and better understanding of ductile materials’ deformation properties.

Changes in Magnetic Fields in Tool Steel (SKS93, JIS) under Single Tensile Load

2013 ◽  
Vol 307 ◽  
pp. 144-148 ◽  
Author(s):  
Katsuyuki Kida ◽  
Megumi Uryu ◽  
Takashi Honda ◽  
Teruaki Shimoji ◽  
Edson Costa Santos ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Tool Steel ◽  
Three Dimensional ◽  
Tensile Load ◽  
Steel Specimen ◽  
Tensile Loading ◽  
Hall Probe ◽  
Observation Methods ◽  
Probe Microscope ◽  
Non Destructive

Fatigue failure of machine components is caused by cyclic load. Non-destructive observation methods that can be related to stress are necessary to study the fatigue phenomena. In the present work, a three-dimensional scanning Hall probe microscope (SHPM) equipped with GaAs film sensors was used to observe the fundamental features of the magnetic fields in a tool steel specimen (SKS93, JIS B 4404: 2006, equivalent to AISI W4 tool steel) during tensile loading. The nature of the magnetic fields during tensile loadings of 430μstrain and 640μstrain was observed using the SHPM. It was found that the magnetic fields decrease due to the tensile loading.

scholarly journals APPLICATION OF STEEL FIBRES IN ALKALI-ACTIVATED MORTARS

2020 ◽  
Vol 27 ◽  
pp. 90-95
Author(s):  
Götz Hüsken ◽  
Lars-Christian Wagner ◽  
Gregor J. G. Gluth ◽  
Stephan Pirskawetz ◽  
Hans-Carsten Kühne
Keyword(s):  
Failure Modes ◽  
Tensile Tests ◽  
Single Fibre ◽  
Image Correlation ◽  
Destructive Testing ◽  
Steel Fibres ◽  
High Durability ◽  
Direct Tensile ◽  
Non Destructive ◽  
Alkali Activated

Alkali-activated materials are ideal for the repair of concrete structures in harsh environmental conditions due to their high durability in chemically aggressive environments. However, slag-based mortars, in particular, are prone to shrinkage and associated cracks. In this respect, the application of steel fibres is one solution to reduce the formation of shrinkage induced cracks and to improve post cracking behaviour of these mortars. This study investigated the influence of two different types of steel fibres on the tensile properties of two alkali-activated mortars. Direct tensile tests and single fibre pull-outs were performed to analyse the determining failure modes both on macro and micro scale. Mechanical testing was accompanied by non-destructive testing methods such as digital image correlation and acoustic emission for a detailed analysis of the fracture process.

scholarly journals Hot Deformation Behavior of a 2024 Aluminum Alloy Sheet and its Modeling by Fields-Backofen Model Considering Strain Rate Evolution

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 243 ◽  
Author(s):  
Zhubin He ◽  
Zhibiao Wang ◽  
Yanli Lin ◽  
Xiaobo Fan
Keyword(s):  
Aluminum Alloy ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Strain Distribution ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Image Correlation ◽  
Aluminum Alloy Sheet ◽  
2024 Aluminum Alloy ◽  
Local Flow

The deformation behavior of a 2024 aluminum alloy sheet at elevated temperatures was studied by uniaxial hot tensile tests over the nominal initial strain rate range of 0.001–0.1 s−1 and temperature range of 375–450 °C. In order to analyze the deformation behavior with higher accuracy, a digital image correlation (DIC) system was applied to determine the strain distribution during hot tensile tests. Local stress-strain curves for different local points on the specimens were calculated. The strain rate evolution of each point during the tensile tests was investigated under different deformation conditions. Then, an improved Fields–Backofen (FB) model, taking into account the local strain rate evolution instead of the fixed strain rate, was proposed to describe the constitutive behaviors. It has been found that obvious non-uniform strain distribution occurred when the true strain was larger than 0.3 during hot tensile tests. The strain rate distribution during deformation was also non-uniform. It showed increasing, steady, and decreasing variation tendencies for different points with the increasing of strain, which led to the local flow stress being different at different local points. The flow stresses predicted by the improved FB model showed good agreement with experimental results when the strain rate evolutions of local points during tensile tests were considered. The prediction accuracy was higher than that of traditional FB models.

scholarly journals Low velocity impact behaviour and post-impact characteristics of kenaf/glass hybrid composites with various weight ratios

2019 ◽  
Vol 8 (3) ◽  
pp. 2662-2673 ◽  
Author(s):  
Muhammad F. Ismail ◽  
Mohamed T.H. Sultan ◽  
Ahmad Hamdan ◽  
Ain U.M. Shah ◽  
Mohammad Jawaid
Keyword(s):  
Hybrid Composites ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Impact Behaviour ◽  
Post Impact ◽  
Impact Characteristics
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