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RISS 인기검색어
- 검색키워드
- 저자 : Del Prete Antonio (검색결과 4 건)
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Metal forming process effect evaluation on structural behavior of an aeronautic panel
Del Prete Antonio,Primo Teresa,Anglani Alfredo 한국소성가공학회 2010 기타자료 Vol.2010 No.6
Forming operations for metal parts can dramatically alter the property of the part and the effects can sometimes strongly influence the structural performance. Generally, for structural simulations it is normal to assume uniform initial conditions, such as thickness distribution and yield strength. This is often a reasonable assumption, but there are several examples of instances where non-uniform properties caused by the manufacturing process effect produces significant changes on the part performance [1?3]. In the case of crashworthiness analysis, where plastic strain deformation takes place, it is fundamental to take in account the manufacturing process effect. In fact it is important to understand how the forming steps affect the performance of the component in terms of: energy absorption, pick load and deformation mode. For the structural performance of aeronautic panel usually nominal conditions are taken into account however the forming steps affect significantly the thickness distribution which can lead to a different linear static behavior of the studied component. Authors have developed a methodology that allows to understand the effect of the forming process for a structural component about the request performance such as the stiffness.
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Chiara Del Prete,Francesca Ciani,Simona Tafuri,Maria Pia Pasolini,Giovanni Della Valle,Veronica Palumbo,Lucia Abbondante,Antonio Calamo,Vincenza Barbato,Roberto Gualtieri,Riccardo Talevi,Natascia Cocc 대한수의학회 2018 Journal of Veterinary Science Vol.19 No.5
This study investigated the correlation between oxidative stress status and key canine sperm parameters and the effect of addition of a superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) combination in egg yolk tris-citrate glucose (EYT-G) extender on semen during 10 days of storage at 4oC. Ten Boxer dogs were divided into two groups, fertile (F) and hypofertile (H), depending on pregnancy and live birth rate status in the previous year. Semen evaluation was performed on the day of collection (D0) and after 5 (D5) and 10 (D10) days of cooled storage. Sperm motility, kinetic parameters, and DNA integrity were assessed. A correlation between oxidative status and key semen parameters in both F and H groups was observed. Total and progressive motilities were significantly higher in the treated (SOD, CAT, and GPx addition) versus control groups at D10 in both F and H groups, and at D5 in the H group. DNA integrity was significantly higher in both treated groups (H and F) at D5 and D10. In conclusion, the addition of SOD, CAT, and GPx in the extender allows preservation of semen quality for up to 10 days of storage at 4oC in both fertile and hypofertile dogs.
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Sheet Hydroforming Pre-bulging Numerical Model Improvement
Papadia Gabriele,Del Prete Antonio,Anglani Alfredo 한국소성가공학회 2010 기타자료 Vol.2010 No.6
Sheet hydroforming has gained increasing interest during the last years, especially as application in the manufacturing of some components for automotive, aerospace, and electrical appliances[1,2]. Many parameters influence the process of sheet hydroforming, one of them is the pre-bulging[3]. Different studies have been also done to determine the optimal forming parameters through FEA[4,5]. In the case of sheet hydromechanical forming process the blank is first placed on the lower die (a fluid chamber combined with draw ring) and then, after sealing the blank between blank holder and draw ring, punch progresses to deform the blank[6]. Pressure of the fluid chamber is also increased simultaneously with the punch progression[7]. In this paper, the pre-bulging effect on active hydromechanical deep drawing process has been investigated experimentally and numerically. Pre-bulging includes two parameters: pre-bulging height and pre-bulging pressure, which influence the forming process significantly[3]. Numerical simulations and experimental tests were carried out for a given shape to investigate the pre-bulging effect on the maximum hydroforming depth. During this activity, the authors have verified that the low numerical ? experimental accuracy detected it was caused also by the simulation of the pre-bulging phase. The authors have analyzed the problem to define a correct procedure to simulate the pre-bulging phase. From this point of view, nine different levels of pre-bulging (taking into account the level equal to zero also) have been tested to experimentally calculate the Thickness Percentage Reduction (TPR) at the maximum pre-bulging height. For each level, the experiment has been conducted two times for a total number of eighteen experiments. The experimental TPR values have been compared with the numerical ones reaching a good accuracy only in the case of pre-bulging height greater than forty millimeters. The experimental activity has given a valid contribution to improve the simulation models reliability and to obtain useful information on the process itself. The effects of pre-bulging on the process performance are also discussed.
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Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis
Papadia Gabriele,Del Prete Antonio,Anglani Alfredo 한국소성가공학회 2010 기타자료 Vol.2010 No.6
The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.
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