Experimental Study on Damage Mechanical Characteristics of Heat-Treated Granite under Repeated Impact

2018 ◽  
Vol 30 (11) ◽  
pp. 04018274 ◽  
Author(s):  
Zhiliang Wang ◽  
Nuocheng Tian ◽  
Jianguo Wang ◽  
Jiacai Liu ◽  
Li Hong
2021 ◽  
pp. 002199832199432
Author(s):  
Yacine Ouroua ◽  
Said Abdi ◽  
Imene Bachirbey

Multifunctional composite materials are highly sought-after by the aerospace and aeronautical industry but their performance depends on their ability to sustain various forms of damages, in particular damages due to repeated impacts. In this work we studied the mechanical behavior of a layered glass-epoxy composite with copper inserts subjected to fatigue under repeated impacts with different energy levels. Damage evolution as a function of impact energy was carefully monitored in order to determine the effect of the copper inserts on mechanical characteristics of the multifunctional composite, such as endurance and life. Results of repeated impact tests show that electric current interruption in the copper inserts occurs prior to the total perforation of the composite material, and after about 75% of the total number of impacts to failure. This is the case for the three energy levels considered in this study, [Formula: see text] = 2, 3 and 4 Joules. The epoxy resin was dissolved chemically in order to preserve the mechanical structure of the damaged copper inserts and the composite fibers for further inspection and analysis. Scanning electron microscopy (SEM) of the fractured copper inserts revealed interesting information on the nature of the damage, including information on plastic deformation, strain hardening, cracking mode, temperature increase during the impacts, and most importantly the glass fibers and their roles during the impact-fatigue tests.


2018 ◽  
Vol 772 ◽  
pp. 23-27
Author(s):  
Takashi Amemiya ◽  
Toshiyuki Yasuhara

Since CNTs (carbon nanotubes) have excellent electrical and mechanical characteristics, their application as fillers for polymer matrix composites is expected to have great potential. The purpose of this study is to clarify the effect of CNT’s crystallinity quality, which is given by high temperature treatment (i.e. annealing), on the properties of CNT/polymer composites. In this study, double wall type CNT (DWNT) and multi wall type CNT (MWNT) were used and heat treated at up to 2000°C to achieve highly improved crystallinity. Electrical and mechanical properties of the CNT/polymer composites were compared with the various CNT’s crystallinity qualities as measured by ID/IG ratios. As a result, although the composites with higher quality CNTs showed considerably lower surface resistivities, however the same composites had lower Young's modulus and tensile strengths. The reason is thought to be that the high quality CNT has low surface activity and weak adhesion between the polymer and the CNT surface. This suggests that CNTs with higher quality do not always contribute to the improvement to the properties of CNT/polymer composites.


2013 ◽  
Vol 820 ◽  
pp. 67-70
Author(s):  
Tuo Li ◽  
Hong Bai Bai ◽  
Chun Hong Lu

Knitted-dapped metal rubber was developed to solve problems of metal rubber with low stiffness and test samples with different sizes were manufactured. Static tests and dynamic tests were carried out to study influences of density and thickness on the static stiffness and influences of frequency, amplitude and preload on dynamic characteristics. Results show that static stiffness rises when density or thickness increases. Frequency has little influence on dynamic characteristics. Knitted-dapped metal rubber will have smaller stiffness and better characteristics of damping, if amplitude increases; if preload increases, energy consumed in the vibration will be more.


2015 ◽  
Vol 25 (2) ◽  
pp. 1-5
Author(s):  
Stefania Farinon ◽  
Pasquale Fabbricatore ◽  
Riccardo Musenich ◽  
Giovanni Bellomo ◽  
Massimo Sorbi ◽  
...  

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