Failure analysis of footbridge made of composite materials

2013 ◽  
pp. 389-392 ◽  
Author(s):  
J Chróścielewski ◽  
I Kreja ◽  
A Sabik ◽  
B Sobczyk ◽  
W Witkowski
Keyword(s):  
Composite Materials ◽  
Failure Analysis

Failure Analysis in Hybrid Composite Laminates Using Acoustic Emission and Microscopy

2015 ◽  
Author(s):  
Mostefa Bourchak ◽  
Yousef Dobah ◽  
Abdullah Algarni ◽  
Adnan Khan ◽  
Waleed K. Ahmed
Keyword(s):  
Acoustic Emission ◽  
Composite Materials ◽  
Failure Analysis ◽  
Hybrid Composite ◽  
Failure Modes ◽  
Glass Fibers ◽  
Frp Composite ◽  
Reinforced Plastic ◽  
Microscopy Techniques ◽  
Damage Type

Fiber Reinforced Plastic (FRP) composite materials are widely used in many applications especially in aircraft manufacturing because they offer outstanding strength to weight ratio compared to other materials such as aluminum alloys. The use of hybrid composite materials is potentially an effective cost saving design while maintaining strength and stiffness requirements. In this work, Woven Carbon Fibers (WCFs) along with Unidirectional Glass Fibers (UDGFs) are added to a an aerospace-rated epoxy matrix system to produce a hybrid carbon and glass fibers reinforced plastic composite plates. The manufacturing method used here is a conventional vacuum bagging technique and the stacking sequence achieved consists of a symmetric and balanced laminate (±451WCF, 03UDGF, ±451WCF) to simulate the layup usually adopted for helicopter composite blades constructions. Then, tensile static tests samples are cut according to ASTM standard using a diamond blade and tested using a servohydraulic test machine. Acoustic Emission (AE) piezoelectric sensors (transducers) are attached to the samples surface using a special adhesive. Stress waves that are released at the moments of various failure modes are then recorded by the transducers in the form of AE hits and events (a burst of hits) after they pass through pre-amplifiers. Tests are incrementally paused at load levels that represent significant AE hits activity which usually corresponds to certain failure modes. The unbroken samples are then thoroughly investigated using a high resolution microscopy. The multi load level test-and-inspect method combined with AE and microscopy techniques is considered here to be an innovation in the area of composite failure analysis and damage characterization as it has not been carried out before. Results are found to show good correlation between AE hits concentration zones and the specimens damage location observed by microscopy. Waveform analysis is also carried out to classify the damage type based on the AE signal strength energy, frequency and amplitude. Most of the AE activity is found to initiate from early matrix cracking that develops into delamination. Whereas little fiber failure activity has been observed at the initial stages of the load curve. The results of this work are expected to clear the conflicting reports reported in the literature regarding the correlation of AE hits characteristics (e.g. amplitude level) with damage type in FRP composite materials. In addition, the use of a hybrid design is qualitatively assessed here using AE and microscopy techniques for potential cost savings purposes without jeopardizing the weight and strength requirements as is the case in a typical aircraft composite structural design.

Experimental and numerical failure analysis of pinned-joints in composite materials

2009 ◽  
Vol 89 (3) ◽  
pp. 459-466 ◽  
Author(s):  
Alaattin Aktaş ◽  
Hüseyin İmrek ◽  
Yusuf Cunedioğlu
Keyword(s):  
Composite Materials ◽  
Failure Analysis ◽  
Pinned Joints

scholarly journals Failure Analysis of Woven Kevlar/Epoxy under Uniaxial Tension

2018 ◽  
Vol 7 (4.26) ◽  
pp. 235
Author(s):  
Norzihan Rahimi ◽  
Ahmad Kamil Hussain ◽  
Mohd Sultan Ibrahim Shaik Dawood ◽  
Adib Zulfadhli Mohd Alias ◽  
Muhamed Hafiy Afiq Md Yusoff ◽  
...  
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Failure Analysis ◽  
Uniaxial Tension ◽  
Weight Ratio ◽  
High Strength ◽  
Fiber Failure ◽  
Stress Theory ◽  
Failure Behaviour ◽  
Finite Element Software

The increasing demand for newer materials with versatile properties such as high strength-to-weight ratio; has made fiber reinforced composite materials a favourable choice in various applications, particularly in the automotive, aerospace, marine, sports and defense industries. Moreover, the properties of a composite material could be tailored for specific functions or applications. Despite its many attractive features, composite material fails in a complex manner involving matrix failure, fiber failure and delamination. This failure behaviour needs to be well established. The objective of this study is to perform failure analysis on a woven Kevlar/Epoxy composite laminate subjected to uniaxial tension and establish its failure trend. The lamination sequence is (θ4/04/-θ4)S where the angle, θ, ranges from 0o to 90o. The failure analysis was carried out using a commercial finite element software, Ansys and comparisons were made using analytical methods (Matlab). The values of stresses were computed and Maximum Stress Theory was employed to check for failure. The trend of failure, in terms of the failure curves (normalized first ply failure and last ply failure loads), for woven Kevlar/Epoxy was established. This study had produced new failure datas for woven Kevlar/Epoxy and thus, contributes significant knowledge about the failure behaviour of composite materials.  

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