A. Del Prete | Università Del Salento (original) (raw)

Papers by A. Del Prete

International Journal of Material Forming, 2008

$Research paper thumbnail of On the appearance of fractional operators in non-linear stress–strain relation of metals$

International Journal of Non-Linear Mechanics

Finding an accurate stress-strain relation, able to describe the mechanical behavior of metals du... more Finding an accurate stress-strain relation, able to describe the mechanical behavior of metals during forming and machining processes, is an important challenge in several fields of mechanics, with significant repercussions in the technological field. Indeed, in order to predict the real mechanical behavior of materials, constitutive laws must be able to take into account elastic, viscous and plastic phenomena. Most constitutive models are based on empirical evidence and/or theoretical approaches, and provide a good prediction of the mechanical behavior of several materials. Here we present a non linear stress-strain relation based on fractional operators. The proposed constitutive law is based on integral formulation, and takes into account the viscoelastic behavior of the material and the inelastic phenomenon that appears when the stress reaches a particular yielding value. A specific case of the proposed constitutive law for imposed strain history is used to fit experimental data obtained from tensile tests on two kind of metal alloys. A best-fitting procedure demonstrates the accuracy of the proposed stress-strain relation and its results are compared to those obtained with some classical models. We conclude that the proposed model provides the best results in predicting the mechanical behavior for low and high values of stress/strain.

The International Journal of Advanced Manufacturing Technology

AIP Conference Proceedings, 2007

ABSTRACT A metal forming simulation tool has been used in a non conventional way. Infact, instead... more ABSTRACT A metal forming simulation tool has been used in a non conventional way. Infact, instead to use numerical codes in order to simulate, verify or optimize a metal forming process like sheet hydroforming, in this specific case, numerical simulation has been used to support the definition of an experimental activity having as objective the attempt to define a correlation between the process performance and its variables. Sheet metal panel hydroforming is a well known technique. It has been recognized like a real opportunity for medium-low volume productions in alternative to conventional metal forming processes. The given technological opportunity it is not evaluated as fully positive due to the difficulty to manage the high number of process variables: fluid chamber pressure, blank holder force distribution, preforming height, etc. The situation becomes more difficult taking in account geometrical characteristics of the product, like the presence of more than one hydroforming depth, possible deep reverse drawing, small tools radius and so on. The activity reported in this paper illustrates the design of an experimental campaign through the use of simulation tools which allow to define the process design space boundaries. Infact, the use of CAE tools gives the chance to understand the influence of process parameters and geometrical characteristics and then, applying a scientific method to reduce the great number of calculations necessary to simulate all possible combinations, to define a complete and specific experimental campaign.

A metal forming simulation tool has been used in a non conventional way. Infact, instead to use n... more A metal forming simulation tool has been used in a non conventional way. Infact, instead to use numerical codes in order to simulate, verify or optimize a metal forming process like sheet hydroforming, in this specific case, numerical simulation has been used to support the definition of an experimental activity having as objective the attempt to define a correlation between the process performance and its variables. Sheet metal panel hydroforming is a well known technique. It has been recognized like a real opportunity for medium-low volume productions in alternative to conventional metal forming processes. The given technological opportunity it is not evaluated as fully positive due to the difficulty to manage the high number of process variables: fluid chamber pressure, blank holder force distribution, preforming height, etc. The situation becomes more difficult taking in account geometrical characteristics of the product, like the presence of more than one hydroforming depth, po...

International Journal of Material Forming, 2010

... [2] Swadesh Kumar Singh, Amrit Dixit, D. Ravi Kumar, Optimization of the design parameters of... more ... [2] Swadesh Kumar Singh, Amrit Dixit, D. Ravi Kumar, Optimization of the design parameters of modified die in hydro-mechanical deep drawing using LS-DYNA, Int. J. Adv. Manuf. Technol. ... [5] Yi Qin, Raj Balendra, Design considerations for hydromechanical deep drawing of ...

AMST’05 Advanced Manufacturing Systems and Technology, 2005

International Journal of …, 2010

Advances in Engineering Software, 2010

Structural Optimization techniques are a well-known approach in order to improve Product Performa... more Structural Optimization techniques are a well-known approach in order to improve Product Performances. Optimization procedures, many times, do not include manufacturing constraints arising from the Corporate technologies. This aspect becomes a disadvantage in the Design revue phase when the final Product release is a trade-off between the Optimization results and the Manufacturing constraints. This paper describes a specific new approach which considers product/process guidelines an input/output data in the optimization phase. The study case is represented by a high performances aeronautic seat structure having as mission profiles the SAE-AS Standards, in order to demonstrate occupant protection when a seat/occupant/restraint system is subjected to statically applied ultimate loads and to dynamic impact test conditions. The authors’ aim, in accordance to standards requirements, is to achieve a final design based on an optimized structural solution for the chosen process technologies taking into account the low volume production, typical attitude of the aeronautical industry. The presented study case offers the proper reference in order to extend this methodology to more complex structural applications.

The aim of this work is to analyze the influence of cutting conditions on surface roughness with ... more The aim of this work is to analyze the influence of cutting conditions on surface roughness with slot end milling on AL7075-T6. The considered parameters are: cutting speed, feed, depth of cutting and mill radial engage. Response surface models based on experimental data obtained with physical tests have been developed, the authors have performed a consistent set of experimental tests based on design points selected within the four-dimensional design space. Each test has been repeated 3 times to ensure the stability of the collected statistical data. These welldistributed results has been subsequently used to create RS models through approximation techniques based on polynomial and neural network methods and to verify their reliability in terms of correct responses behaviour. The obtained results show that the most significant factors affecting the surface roughness are feed and speed.

... REFERENCES [1] Mohammad Habibi Parsa, Payam Pournia, Optimization of initial blank shape pred... more ... REFERENCES [1] Mohammad Habibi Parsa, Payam Pournia, Optimization of initial blank shape predicted based on inverse finite element method, Finite Elements in Analysis and Design 43 ... (7) [3] Hariharasudhan Palaniswamy, Gracious Ngaile, Taylan Altan, Optimization of ...