Investigations on the Residual Shear Properties of a Composite Subjected to Impact Fatigue Loading

2016 ◽  
pp. 375-386
Author(s):  
Said Mouhoubi ◽  
Krimo Azouaoui
Keyword(s):  
Fatigue Loading ◽  
Impact Fatigue ◽  
Shear Properties

Effect of Impact-Fatigue on Damage in Adhesive Joints

2007 ◽  
Vol 347 ◽  
pp. 653-658 ◽  
Author(s):  
Juan Pablo Casas-Rodriguez ◽  
Ian A. Ashcroft ◽  
Vadim V. Silberschmidt
Keyword(s):  
Damage Evolution ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Loading ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Bonded Joints ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Low Velocity

In recent decades the use of structural adhesive joints in the aerospace industry has increased considerably thanks to their high strength-to-weight ratio, low stress concentration and capacity to join different adherends. There is increasing interest in damage due to low-velocity impacts produced in adhesively bonded components and structures by vibrating loads. This type of loading is known as impact fatigue. The main aim of this paper is to investigate damage evolution in adhesive joints subjected to impact-fatigue and to compare this with damage evolution in standard fatigue (i.e. non-impacting, constant amplitude, sinusoidal fatigue). In this work, adhesively bonded lap joints were subjected to multiple tensile impacts tensile and it was seen that this type of loading was extremely damaging compared to standard fatigue. A number of methods of studying damage evolution in bonded joints subjected to fatigue and impact fatigue loading have been investigated and various parameters have been used to characterise these processes. Two modifications of the accumulated time-stress model [1-4] are proposed and it is shown that both models provide a suitable characterization of impact-fatigue in bonded joints.

scholarly journals Damage assessment in CFRP laminates exposed to impact fatigue loading

2011 ◽  
Vol 305 ◽  
pp. 012047 ◽  
Author(s):  
George Tsigkourakos ◽  
Vadim V Silberschmidt ◽  
I A Ashcroft
Keyword(s):  
Damage Assessment ◽  
Fatigue Loading ◽  
Impact Fatigue ◽  
Cfrp Laminates

scholarly journals Fatigue life assessment of TTC streetcar concrete pavements

2021 ◽  
Author(s):  
Bahram Farhang
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Life Assessment ◽  
Superior Performance ◽  
Experimental Program ◽  
Impact Fatigue ◽  
Construction Methods ◽  
The Impact

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.

Delamination-Crater Interaction in Damage of Glass/Epoxy Composite Plates Subjected to Impact Fatigue

2012 ◽  
Vol 498 ◽  
pp. 139-150 ◽  
Author(s):  
Said Mouhoubi ◽  
Krimo Azouaoui
Keyword(s):  
Energy Levels ◽  
Composite Plates ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Woven Fabric ◽  
Impact Fatigue ◽  
Repeated Impact ◽  
Crater Size ◽  
Composite Glass ◽  
Impact Energies

The use of composite materials is increasing although their behavior under impact fatigue loading remains rather unknown. This study is to assess the evolution of damage, especially delamination and crater, in a composite Glass/Epoxy woven fabric, using repeated impact tests at low energy levels (<10J). Both types of damage that arise and grow within the material cannot be independent from each other. Our objective in this work is to establish the interaction between two damages (delamination and crater) on laminate damage, and understand the contribution of each of them in the different phases through which passes the composite before perforation. To do this, impact fatigue tests are carried out on composite plates and measures of the crater size (diameter and depth) and the size of the delaminated area (diagonals from a diamond shape) are collected for different numbers of impacts and impact energies. A question worth asking; can we foster one of these damages over the other? especially when we are interesting to the “structure applications”, where one "prefers" perforation to delamination (while completing correctly the function's intended to the structure), or “shielding applications”, where one "prefers" the delamination to perforation. Although the range of impact velocities is not the same, it is still interesting to consider the synergy between these two damages at low impact velocities, always in the case of “structure applications” and “shielding applications”.

Mixed-mode crack growth in bonded composite joints under standard and impact-fatigue loading

2008 ◽  
Vol 43 (20) ◽  
pp. 6704-6713 ◽  
Author(s):  
Ian A. Ashcroft ◽  
Juan Pablo Casas-Rodriguez ◽  
Vadim V. Silberschmidt
Keyword(s):  
Crack Growth ◽  
Mixed Mode ◽  
Fatigue Loading ◽  
Composite Joints ◽  
Impact Fatigue ◽  
Mixed Mode Crack ◽  
Bonded Composite

An observation of crack initiation and early crack growth under impact fatigue loading

1999 ◽  
Vol 271 (1-2) ◽  
pp. 390-394 ◽  
Author(s):  
Meng Zhang ◽  
Pinsheng Yang ◽  
Yuxu Tan ◽  
Yan Liu ◽  
Shupeng Gong
Keyword(s):  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Loading ◽  
Impact Fatigue

Testing of In-Plane Shear Properties under Fatigue Loading

1995 ◽  
Vol 14 (9) ◽  
pp. 965-987 ◽  
Author(s):  
Larry B. Lessard ◽  
Olivia P. Eilers ◽  
Mahmood M. Shokrieh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
High Stress ◽  
Fatigue Loading ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Plane Shear ◽  
Shear Properties ◽  
Notched Specimens

A two-dimensional finite element analysis is performed in order to analyze and improve the performance of the three-rail shear test specimen as prescribed by the ASTM Standard Guide for testing of in-plane shear properties of composite laminates [1]. Of main interest is the location of high-magnitude stresses in the matrix direction that affect the fatigue life of the specimen. Through finite element analysis, the optimal specimen configuration is determined by inserting slots in the positions at which there are stress concentrations. This has the effect of transferring the location of high stress away from critical areas, thus increasing the fatigue life of the specimen. The results are verified by three-rail shear tests performed for both standard un-notched and new notched specimens. The notched specimens show great improvement in both static strength and fatigue life.

scholarly journals Fatigue life assessment of TTC streetcar concrete pavements

2021 ◽  
Author(s):  
Bahram Farhang
Keyword(s):  
Life Cycle ◽  
Service Life ◽  
Fatigue Cracks ◽  
Fatigue Loading ◽  
Life Assessment ◽  
Superior Performance ◽  
Experimental Program ◽  
Impact Fatigue ◽  
Construction Methods ◽  
The Impact

The Toronto Transit Commission, TTC traditional embedded track for mechanically jointed rails, is performing satisfactory except for accelerated surface concrete deterioration. By far the most damaging group of deterioration processes in streetcars concrete pavement is due to wheel impact on the joints which will subsequently excite a response on the track. The enhancement of special trackwork, STW service life was the initiative to explore encapsulation technology advances in embedded track materials and construction methods. This aimed to extend the life cycle of the track from current average of 15 years towards target life of 50 years. In the present study, attempts at finding and patterning the localized cracks, especially wheel impact fatigue cracks, are carried out. This issue was investigated during the course of an experimental program demonstrated by simulating the wheel impact loading in concrete under repeated load application. Specially designed specimens were used to represent sheet rubber and urethane encapsulation system proposal against the current assembly. This research reviews the pros and cons of various factors influencing the life cycle of the current assembly and examining and assessing between alternative track construction methods and materials at the joints and examining the concrete's performance both during the impact fatigue loading resulting in inclined cracking and ongoing service life and durability issues under combined environmental and mechanical loadings. Experimental results show that it is possible to achieve the targeted service life of 50 years, based on minimum of 10 time superior performance for either of the proposed encapsulation technologies vs. current construction methods.

Evaluation of damage within sandwich honeycomb panels subjected to impact fatigue loading

2021 ◽  
pp. 002199832110442
Author(s):  
Ahcene Oubouzid ◽  
Boualem Keskes ◽  
Benoit Vieille
Keyword(s):  
Fatigue Loading ◽  
Damage Parameter ◽  
Honeycomb Core ◽  
Multiple Impacts ◽  
Impact Fatigue ◽  
Bending Tests ◽  
The Core ◽  
Repeated Impacts ◽  
The Impact ◽  
Good Agreement

This work was aimed at investigating damage evolution within sandwich panels consisting of aluminum skins and Nomex™ honeycomb core, with three different values of the core densities, subjected to multiple impacts. Repeated impacts at low energy were conducted using an impact fatigue machine. Bending tests were conducted to determine the residual stiffness after impacts in order to analyze the evolution of a damage parameter D. A model was therefore proposed for describing the changes in this parameter as a function of impact cycles N. After repeated impacts, the D(N) curves are characterized by an S-shaped curve. A good agreement is observed between model and experimental results, the maximum standard deviation being less than 7% for different densities. Microscopic observations of the impacted specimens were conducted in order to evaluate the crater growth (associated with permanent indentation). The influence of the number of impacts on the dimensions of the impact zone has also been evaluated. For all the core densities, the permanent indentation gradually increases as a function of impact cycles.

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