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Experimental verification of RV-MTS model for fracture in soda–lime glass weakened by a V-notch
M. R. Ayatollahi,A. R. Torabi 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.10
Fracture phenomenon was experimentally investigated in a soda–lime glass weakened by a V-notch under tensile-shear loading. Fracture tests were conducted using a new test sample called the V-notched Brazilian disc (V-BD) specimen. The fracture resistance and fracture initiation angle were obtained initially from the test results. Afterward, a fracture model was utilized to estimate the experimental results. Very good correlation was found between the experimental and theoretical results both for the fracture resistance and the fracture initiation angle in notches having different notch angles and various notch tip radii. Experimental results revealed that for a constant notch tip radius, the failure load under pure tensile loading conditions decreases as the notch angle increases. For a constant notch angle,as the notch tip radius increases, the fracture load in the soda–lime glass V-BD specimens enhances in the whole domain from pure tensile to pure shear loading. Moreover, for a constant notch tip radius, the notch angle has almost no effect on the fracture initiation angle when the specimen is predominantly under tensile loading conditions.
Torabi, A.R.,Berto, F. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
A fracture criterion based on the strain energy density (SED) over a control volume, which embraces the notch edge, is employed in the present paper to assess the fracture loads of some U-notched Brazilian disk (UNBD) specimens. The specimens are made of commercial graphite and have been tested under pure mode I, pure mode II and mixed mode I/II loading. The results show that the SED criterion allows to successfully assess the fracture loads of graphite specimens for different notch tip radii and various mode mixity conditions with discrepancies that fall inside the scatter band of ${\pm}20%$.
Out-of-plane ductile failure of notch: Evaluation of Equivalent Material Concept
A. R. Torabi,Behnam Saboori,M. R. Kamjoo 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.5
In the present study, the fracture toughness of U-shaped notches made of aluminum alloy Al7075-T6 under combined tension/out-of-plane shear loading conditions (mixed mode I/III) is studied by theoretical and experimental methods. In the experimental part, U-notched test samples are loaded using a previously developed fixture under mixed mode I/III loading and their load-carrying capacity (LCC) is measured. Then, due to the presence of considerable plasticity in the notch vicinity at crack initiation instance, using the Equivalent Material Concept (EMC) and with the help of the point stress (PS) and mean stress (MS) brittle failure criteria, the LCC of the tested samples is predicted theoretically. The EMC equates a ductile material with a virtual brittle material in order to avoid performing elastic-plastic analysis. Because of the very good match between the EMC-PS and EMC-MS combined criteria with the experimental results, the use of the combination of the criteria with EMC is recommended for designing U-notched aluminum plates in engineering structures. Meanwhile, because of nearly the same accuracy of the two criteria and the simplicity of the PS criterion relations, the use of EMC-PS failure model in design of notched Al7075-T6 components is superior to the EMC-MS criterion.
A.R. Torabi,F. Berto 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
A fracture criterion based on the strain energy density (SED) over a control volume, which embraces the notch edge, is employed in the present paper to assess the fracture loads of some U-notched Brazilian disk (UNBD) specimens. The specimens are made of commercial graphite and have been tested under pure mode I, pure mode II and mixed mode I/II loading. The results show that the SED criterion allows to successfully assess the fracture loads of graphite specimens for different notch tip radii and various mode mixity conditions with discrepancies that fall inside the scatter band of ±20%.
Averaged strain energy density to assess mixed mode I/III fracture of U-notched GPPS samples
Behnam Saboori,A. R. Torabi,F. Berto,S. M. J. Razavi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6
In the present contribution, fracture resistance of U-notched GPPS members under mixed mode I/III loading conditions is assessed by using the Averaged Strain Energy Density (ASED) criterion. This criterion has been founded based on the ASED parameter averaged over a well-defined control volume embracing the notch edge. The validation of the theoretical criterion predictions is evaluated through comparing with the results of a series of mixed mode I/III fracture tests conducted on rectangular-shaped GPPS specimens weakened by a single edge U-notch. A recently developed apparatus for mixed mode I/III fracture experiments is employed for measuring the fracture loads of the specimens. The test samples are fabricated with different notch tip radii with the aim of evaluating the influence of this major feature of the U-notched components on the mixed mode I/III fracture behavior. It is shown that the onset of brittle fracture in U-notched GPPS specimens under various combinations of tension and out-of-plane shear can well be predicted by means of the ASED criterion.
Averaged strain energy density to assess mixed mode I/III fracture of U-notched GPPS samples
Saboori, Behnam,Torabi, A.R.,Berto, F.,Razavi, S.M.J. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6
In the present contribution, fracture resistance of U-notched GPPS members under mixed mode I/III loading conditions is assessed by using the Averaged Strain Energy Density (ASED) criterion. This criterion has been founded based on the ASED parameter averaged over a well-defined control volume embracing the notch edge. The validation of the theoretical criterion predictions is evaluated through comparing with the results of a series of mixed mode I/III fracture tests conducted on rectangular-shaped GPPS specimens weakened by a single edge U-notch. A recently developed apparatus for mixed mode I/III fracture experiments is employed for measuring the fracture loads of the specimens. The test samples are fabricated with different notch tip radii with the aim of evaluating the influence of this major feature of the U-notched components on the mixed mode I/III fracture behavior. It is shown that the onset of brittle fracture in U-notched GPPS specimens under various combinations of tension and out-of-plane shear can well be predicted by means of the ASED criterion.
S. M. Hatefi,F. Jolai,S. A. Torabi,R. Tavakkoli-Moghaddam 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4
Although disruptions rarely occur in the logistics networks, they can cause serious operational consequences and negative financial effects in the long-term. This paper proposes a fuzzy possibilistic programing model for designing a reliable forward-reverse logistics network with hybrid facilities in the presence of both uncertainty and random facility disruptions. For doing so, first several effective reliability strategies, i.e., introducing two kinds of reliable and unreliable facilities, partial and complete capacity disruptions, and a sharing strategy, are defined and incorporated into the developed reliability model to mitigate the impacts of random facility disruptions and improve resiliency of the network. Furthermore, a fuzzy possibilistic programing is utilized to deal with the existing epistemic uncertainties in the network parameters, i.e., fixed opening costs, variable processing and transportation costs, demands, returned products, and capacities. Finally, several numerical tests and also a sensitivity analysis are done to demonstrate the effectiveness and applicability of the proposed model in addition to the potency of the fuzzy possibilistic based solution method in this context.
Agley, Jon,Gassman, Ruth A.,Kolbe, Lloyd,Seo, Dong-Chul,Torabi, Mohammad R. Korean Society for Health Education and Promotion 2012 보건교육건강증진학회지 Vol.29 No.3
Objectives: This study examined the extent to which attitudes about smoke-free air policies (SFAPs) in bars/restaurants, workplaces, all public places, and motor vehicles when minors are present can be explained by individuals' sociodemographic characteristics, smoking status, and beliefs about the health of others. Methods: Data were gathered from 359 individuals age 18 or older who attended the Lawrence County Fair in Indiana, United States, in July, 2009, an area where there were no SFAPs in place at the time of survey administration. Results: Multinomial logistic regression analyses indicated that perceived severity of secondhand smoke (SHS) on others, perceived responsibility of smokers for the harm their SHS causes to others, and perceived susceptibility of others to SHS exposure, along with education level and smoking status, significantly predict opposition to SFAPs in this population. Conclusions: The results of this exploratory study suggest the need for additional research related to attitudes about health policies as well as to the practical applications of these findings for smoke-free air advocacy.