New dimensionless numbers for deformation of circular mild steel plates with large strains as a result of localized and uniform impulsive loading

Author(s):  
Hashem Babaei ◽  
Tohid Mirzababaie Mostofi

This study introduces an empirical analysis approach to assess mechanical behavior of thin circular mild steel plates subjected to uniform and localized impulsive loading. The empirical models have been derived by singular values decomposition procedure to predict midpoint deflection of circular plates. The essence of empirical analysis is based on dimensionless numbers. For this, Jones’s dimensionless number λ is considered as a dimensionless number for both uniform and localized loading. This number has some features such as considering plate geometries, mechanical properties of material, and loading conditions. The well-known Cowper–Symonds constitutive equation has been used to investigate the potential influence of material strain rate sensitivity where the constant parameters in this equation are considered as a function of plate thickness. In localized impulsive loading, two other dimensionless numbers are appended to investigate the effects of changing load ratio and standoff distance. The results of empirical models are compared to the other experimental and theoretical studies which have been performed by different researchers. Also, the obtained results show that the presented models have much less root mean square error than the other ones. Hence, these models are suitable to predict midpoint deflection of thin circular plates subjected to both uniform and localized impulsive loading.

Author(s):  
Hashem Babaei ◽  
Tohid Mirzababaie Mostofi ◽  
Ehsan Armoudli

This paper studies the dynamic plastic response of thin quadrangular mild steel plates subjected to uniform and localized impulsive loading. For this, two new dimensionless numbers based on dimensionless governing equation of plates have been suggested. Four different effective parameters such as plate geometry, inertia of applied load, mechanical properties of material and strain rate sensitivity have been considered in suggested dimensionless numbers. The unknown coefficients of these numbers have been calculated by using singular value decomposition method. In order to illustrate the ability of empirical constitutive equations for predicting the maximum deflection, these equations are compared with different sets of experimental results that have been performed by various researchers. The comparison between the results of present empirical equations and the other theoretical and experimental ones shows that these models are more accurate than the other ones and are suitable to use for predicting the maximum deflection of all quadrangular mild steel plates subjected to uniform and localized loading.


1997 ◽  
Vol 119 (3) ◽  
pp. 332-342 ◽  
Author(s):  
N. Jones ◽  
S.-B. Kim ◽  
Q. M. Li

A theoretical analysis is presented in this paper to predict the dynamic plastic response of aluminium alloy and mild steel circular plates when struck normally by blunt solid cylindrical masses at the center. Reasonable agreement is obtained with experimental results for the permanent transverse displacements. Different failure mechanisms, which have been found in previous experimental studies on aluminium alloy and mild steel plates, are also illustrated by the proposed theory.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ayssar Nahlé ◽  
Ideisan I. Abu-Abdoun ◽  
Ibrahim Abdel-Rahman

The inhibition and the effect of temperature and concentration of trans-4-hydroxy-4′-stilbazole on the corrosion of mild steel in 1 M HCl solution was investigated by weight loss experiments at temperatures ranging from 303 to 343 K. The studied inhibitor concentrations were between  M and  M. The percentage inhibition increased with the increase of the concentration of the inhibitor. The percentage inhibition reached about 94% at the concentration of  M and 303 K. On the other hand, the percentage inhibition decreased with the increase of temperature. Using the Temkin adsorption isotherm, the thermodynamic parameters for the adsorption of this inhibitor on the metal surface were calculated. Trans-4-hydroxy-4′-stilbazole was found to be a potential corrosion inhibitor since it contained not only nitrogen and oxygen, but also phenyl and pyridine rings that are joined together with a double bond (–C=C–) in conjugation with these rings.


Author(s):  
Inés Rojas Avendaño

This essay examines young Venezuelans’ experiences of daily insecurities and critical situations and their responses using the framework of ontological security. The study uses the concept of ‘multiple youths,’ proposed by Latin American scholars, to link the ideas of security and identity, to explore the different intersubjective understandings of these notions in the lives of university students, and to explain their choice of conflict as part of the ordinary. Empirical analysis shows how routinization of conflict has a strong psychological impact on Venezuelan youth’s intersubjective identity formation and interpretation of events as ordinary or threatening. The routinization of conflict is a response to maintaining ontological security, providing a sense of constancy and continuity since it has become part of the routines of university students in Venezuela. In addition, conflict helps eliminate and/or delegitimize the ‘other,’ hence hindering dialogue and a negotiated solution to the current political impasse.


2010 ◽  
Vol 45 (3) ◽  
pp. 317-326 ◽  
Author(s):  
Murat Eyvaz ◽  
Hatice Deniz ◽  
Tuğrul S. Aktaş ◽  
Ebubekir Yüksel ◽  
Ahmet M. Saatçi

Abstract Pre-ozonation–coagulant interactions effects in relation to the coagulant type and dosage in direct filtration of surface waters were investigated. The performance of the process was evaluated by monitoring the effluent quality and head loss development through the filter bed. Two identical pilot scale filter columns filtering the same raw water were operated in parallel. The raw water was brought from Ömerli Reservoir in Istanbul. Before filtering, the raw water flow was split into two equal flows. One of the streams was pre-ozonated and the other was aerated using contact chambers with equal volumes equipped with same number and type of diffusers. In coagulation experiments, one of the filters was operated using aluminum sulfate as a coagulant while the other one was run with ferric chloride. For similar filter run times, the effluent quality was always better with pre-ozonation compared to aeration. It was also observed that, aluminum sulfate application gave more favorable results for both particle and turbidity removal compared to ferric chloride. Ives’ filterability index which incorporates the important filtration design parameters such as: effluent quality, the headloss and the velocity of filtration into a dimensionless number was used for the comparison of the experimental results.


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