Raimondo Pasquino

Pultrusion manufacturing process development by computational modelling and methods

This paper deals with the modelling and development of computational schemes to simulate pultrusion processes. Two different computational methods, finite differences and elements, are properly developed and critically analyzed. The methods are applied to a model, implemented with suitable boundary conditions, proposed in this paper. Simulations, compared with experimental data available in the literature, show a good agreement between theory and experiments.

Pultrusion manufacturing process development: Cure optimization by hybrid computational methods

This paper develops a hybrid approach, based on genetic algorithms and simplex method, to optimize the accuracy of a manufacturing process by material pultrusion. The numerical model, proposed in a recent paper of the same authors, is solved by a finite difference scheme. The analysis technically shows the efficiency of the optimization algorithm.

Finite element analysis of the steel quenching process: Temperature field and solid-solid phase change

This paper deals with a finite element analysis of the steel quenching process; regarding the transient temperature field and the thermally induced solid-solid phase transformations. All the process steps, i.e. heating, holding, and cooling, have been considered, modeling both the austenite formation and decomposition and taking into account nucleation and growth processes. The final hardness distribution into the quenched sample has been predicted according to the rule of mixtures, taking into account the chemical composition of the processing material, the final distribution of each phase and the local cooling rate.

Inverse analysis of the laser forming process by computational modelling and methods

This paper deals with the development of a computational procedure for the inverse analysis of the laser forming process of three-dimensional metal sheet, characterized by double curvature. The procedure is based on the minimization of a vectorial fitness function, obtained by the comparison of the considered target surface with reference deformed surfaces, represented as sixteen point bicubic patches. An FEM-based computational approach has been adopted to evaluate the reference deformed surfaces for the instruction of the processor.

The modelling of thin sheet forming by laser beams heat transfer models toward deformation analysis

This paper deals with the modeling of the thermal field during machining processes by laser beam local heating. The analysis refers to the identification of mathematical models suitable to describe the large variety of complex phenomena which occur during the machining process. Specifically, this paper provides the modelling assessment to deal with the solution of mathematical problems toward simulation and with specific engineering applications related to the above technological system.

Magnetoelastic waves application to investigate laser annealing effects in ferromagnetic glass

Abstract The dependence of magnetoelastic wave amplitude on structure-sensitive parameters, in addition to the possibility of producing and detecting these waves in different parts of a sample, has been used to study the effects induced by laser heating in ferromagnetic materials, during and after heat treatment. Here we report experimental results and theoretical considerations that explain the correlations between the magnetoelastic wave amplitude and the magnetic permeability, the stress sensitivity and the elastic coefficient. In particular, it is shown that structural changes can be seen, and a simple model of thermomagnetic coupling is developed.

Modelling of film casting manufacturing process longitudinal and transverse stretching

Film casting is a widely used manufacturing process used to shape polymers into high quality films for package or other industrial and commercial purposes. The relevant steps of the manufacturing process are the longitudinal and transverse stretching, in which the material assumes the required dimensions and mechanical properties. This paper deals with the modelling of longitudinal and transverse stretching of the film casting process of isotattic polypropylene. These models are based on the suitable analogy (confirmed by experimental data) between the behavior of the polypropylene and some metals and on the remarkable directionality of the mechanical properties of the final product. Modelling leads to evaluation of the profiles of pressure and speed and of normal and tangential stresses.

Temperature fields in machining processes and heat transfer models

This paper deals with the modelling of the heat transfer process with special attention to the characterization of the thermal field during turning processes. Specifically, the measurement of the thermal field and the selection of the proper heat transfer models are dealt with. The analysis is developed in view of the solution of direct and inverse problems.

The influence of working parameters on the response of a capacitive sensor used in-process for the measurement of tool wear

Abstract In a previous research work, a no contact capacitive sensor was obtained which could check superficial characteristics of workpieces during working. This sensor can relate variations of capacity to superficial finishing of the workpiece directly. The present study aims at finding a method for interfacing the capacitive sensor to a system of data acquisition and for deciding the substitution of the tool, automatically. It has been necessary to value the influence of cutting parameters on sensors response in order to find the threshold value, characterizing by itself an anomalous working state owed to regular or irregular tool wear.

A no contact capacitive sensor to mechanical working control

Abstract The aim of this work is to use a capacitive sensor to obtain process control during turning. It will verify if the sensor is able to assess geometrical variation of the workpiece due to accidental tool failure or to regular tool wear. The sensor has no contact with the rotating piece. The experimental work consists in verifying if the capacity valued can be correlated to the real pass depth. The sensor was characterized by static tests measuring the capacity to the roughness variation of sample. The choice of dielectric was determined by the results obtained during the characterization, where it was seen that the best compromise between dimensions and sensibility of the sensor was obtained using a polyester dielectric 42 μm thick.