M.G. El-Sebaie

Plastic instability conditions in the deep-drawing of a circular blank of sheet metal

Abstract Theoretical results are presented for the limiting drawing ratios in the deep-drawing of cylindrical cups with a flat-headed punch. The material properties are characterized by the n- value and R- value . It is shown that at least two instability modes are possible. The first mode in the cup wall occurs under plane strain tension and is most likely to apply to annealed materials. The second mode is in the flange under uniaxial tension and this is most likely to apply to materials that have been previously cold-worked. The introduction of this second mode throws light on an area where previously there has been some discrepancy between the results of previous research workers.

Plastic instability conditions when deep-drawing into a high pressure medium

Abstract Experimental results are presented for the deep-drawing of soft 70/30 brass into a high pressure medium. It is shown that the limiting drawing ratio can be increased from 2.19 for the conventional process to 3.44 for the pressure process and that this increase is made possible by a change in the location and mode of instability. A theoretical analysis is proposed to describe the instability conditions and comparision with the experimental results is good.

Optimum blank shape of cylindrical cups in deep drawing of anisotropic sheet metals

Abstract The present study aims to determine the optimum shape of a blank for the deep drawing of a cylindrical cup without ears. The earing behavior of the deformed cup was predicted from the anisotropic properties of the sheet metals. Sheet metals used in the experiments are low carbon steel and commercially pure aluminum. The nominal thickness was 1.0 mm for all sheets. The modified blank is used to reduce the ear configuration. Comparison between experimental results of circular and modified blanks are included. The punch load and the work requirements were reduced. The limiting drawing ratios were slightly improved.

Double-operation deep-drawing

Abstract By deep-drawing into a high-pressure fluid the limiting drawing ratio can be considerably increased over that obtained in conventional deep-drawing. However, this result is achieved at the cost of greater expenditure of energy and of some form of control system for the high-pressure fluid. The present work proposes a process which does away with these disadvantages. The fluid pressure for the pressure-assisted deep-drawing is directly controlled by a conventional draw and two shells are formed simultaneously. Details are given for the design of compatible systems.

Rubber-Filler Interactions and Its Effect in Rheological and Mechanical Properties of Filled Compounds

This paper will set out a brief review of the needs, early development, and current status of the nature of the interactions between rubber matrix and particulate filler and the intrinsic effect on mechanical and rheological behavior of filled vulcanizates. Fillers are commonly added to commercial elastomers for reasons of economy and also to favourably modify properties such as stiffness, tensile strength, heat distortion, mouldability, and other important properties, such as impact properties and elongation to break. The behavior of elastomers reinforcing with certain fillers like carbon black or high-structure silica need to be understood deeply to clarify the rubber-filler interaction and its effect on rheological and mechanical properties of filled rubber compounds. In this paper the nature of interaction between the elastomer and filler particles, the types of reinforcing fillers, the effect of its size and structure, the reinforcing concepts, and the mechanical properties of filled rubber are discussed.

Optimization of reliability based model for production inventory system

Abstract Traditional research studies on the Economic Production Quantity (EPQ) model propose that produced items have perfect quality. However, in real production systems the quality of the products depends on the production process reliability. EPQ models that consider reliability and the effect of imperfect items are much more complex, and in turn the objective function becomes much more complicated. It is challenging to solve this type of model analytically, and it is also time consuming. Hence, it is necessary to utilize non-traditional solution techniques, such as numerical methods and heuristic search algorithms, for solving this type of model. In this paper, the optimal solution of the EPQ based reliability model are obtained by analytical solution, a Generalized Reduced Gradient (GRG) algorithm, an Evolutionary Algorithm (EA), a Monte Carlo non-deterministic method and the LINGO™ commercial solver. The methodology of this work has been clearly presented, and the computational results are compared and discussed. The computational results show that the GRG, EA, and Monte Carlo methods result in feasible and similar solutions, while the analytical solution is not valid for the model studied. The model can be extended to solve more complicated inventory models considering rework, shortage and multiple products.

Simulation modelling and analysis of a production line

Production lines modelling has many problems that are difficult to be solved using analytical solutions, due to uncertainty and/or variability in variables and parameters. This paper is targeting unreliable production lines with finite buffers for the objective of evaluating and analysing the current situation and identifying bottlenecks. We use discrete event simulation to model a real production line based on one-year historical data about the breakdowns of all the production lines machinery. This data is used to find appropriate probability distributions to represent each machinery downtime and uptime. The simulation model is built using AnyLogic software to abstract the actual production line, and the model is validated using the actual data and information about the production line. Improvement scenarios are proposed to resolve the observed bottlenecks, and therefore give managerial insights to increase the throughput according to the increasing demand. Finally, production plans are set for different demands along the year.

Scheduling problems of automated guided vehicles in job shop, flow shop, and container terminals

Automated guided vehicles have been widely used in flexible manufacturing systems especially in a job shop and flow shop. Recently, they are included in other fields such as container terminals. This paper demonstrates a literature review of the last three decades about the scheduling problems of the automated guided vehicles in three main classes, namely job shops, flow shops, and container terminals. We classify the literature according to the scheduling problems and the solution approaches. The results of the survey are that the solution methods mainly focus on using simulation as a key performance analysis tool, whereas, the big computation times of the developed mathematical models make heuristics approaches are dominant for solving such models. After that, we discuss research gaps to the purpose of finding new research directions.