A state of the art instrumented Drop Weight Impact Tester Machine was developed in Iran University of Science and Technology which measures the energy absorption of composite materials under impact load. The output of the machine is used to draw load- time graph and calculate the amount of energy absorbed by the specimens. The machine was equipped with various sensor systems to measure the velocity of the impactor just before it contacts the specimen and the amount of contact force, and with a data acquisition system to record the force and time history. Capability of testing according to many different types of standards and capability of studying behaviour of the specimen after impact are two important characteristics of this machine. This designed system, after manufacturing and calibration, was installed and successfully utilized.

This paper addresses the application of group Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) to Multiple Criteria Decision Making (MCDM), for assisting decision makers by evaluating, ranking and selecting material handling equipment (MHE). The present study considers engineering economy as one of the erudite tool for performance evaluation of said equipment in the integrated and synergetic way. Lastly, incremental analysis is used for final ranking of the equipment under inquisition.

This paper considers a multi period serial production systems for one product and deals with the problem of planned lead-time calculation in a Material Requirement Planning (MRP) environment under probabilistic lead times. It is assumed that lead times for all stages have the same distribution with different parameters. A MRP approach with periodic order quantity (POQ) policy is used for the supply planning of components. The objective is to minimize the sum of fixed ordering, holding and backlogging costs. A mathematical model is suggested and then an optimal planning lead-time, ordering quantity and periodic time are determined.

During the past two decades, there has been a growing concern on environmental issues around the world. Firms try to provide better production plans to recycle their used materials to reduce pollution from environment. In fact, lack of management in municipal solid waste for methods of collecting, disposal and processing of them can be significant damage to the environment, This paper presents a mathematical model for pet waste management, which plays essential role on municipal solid waste. The modeling formulation is a nonlinear probable mathematical programming model for chemical recycling the PET waste. In this model, the optimal amount of waste is determined by considering collected operations of reverse logistics and chemical recycling when demand is under uncertainty.

One of the primary concerns on supply chain management is to select appropriate suppliers based on different criteria, which are often in serious conflict. In this paper, we present a fuzzy TOPSIS technique to prioritize suppliers on reverse logistic network based on different criteria and then the proposed model of this paper applies fuzzy linear programming technique to determine optimum order quantity associated with each supplier. There are three criteria associated with each supplier including technical skills, equipment and ability to analyze. The implementation of the proposed method has been demonstrated in case study.

Collide of two objects or impact, is one of the main damage initiation reasons. In this paper, impact and damage behavior of elastic and visco-elastic bodies are investigated numerically using the finite element analyses. The results showed that visco-elastic materials, distribute stresses to the edge of model after the impact with a solid body. Furthermore, the impact of elastic and visco-elastic composite materials are analyzed and the variations of stress, displacement, damage energy and the damage patterns during a time period are compared for the two material models. The reduction in the values of stress, displacement and damage energy of visco-elastic material is also determined relative to the elastic composite material.

With an ongoing progress in industries and technologies, most firms and businesses highly depend on cooperation and collaborations within a supply chain. In today’s competitive business environment, customer satisfaction plays an important role for the business survival. These matters can be secured by “supply chain”, a chain consists of various companies working together to maintain customers’ satisfaction. If various stages of different chains cooperate with each other, “supply chain network” (SCN) will be the outcome. In order to have a supply chain network or just a supply chain-operation in its best possible way, some optimization techniques are needed. In this paper, we present a close look at previous studies in the field of SCN optimization techniques and classify them based on the relative important characteristics.

In this paper, a differential quadrature element method (DQEM) is developed for free transverse vibration analysis of a non-uniform cantilever Timoshenko beam with multiple concentrated masses. Governing equations, compatibility and boundary conditions are formulated according to the differential quadrature rules. The compatibility conditions at the position of each concentrated mass are assumed as the continuity in the vertical displacement, rotation and bending moment and discontinuity in the transverse force due to acceleration of the concentrated mass. The effects of number, magnitude and position of the masses on the value of the natural frequencies are investigated. The accuracy, convergence and efficiency of the proposed method are confirmed by comparing the obtained numerical results with the analytical solutions of other researchers. The two main advantages of the proposed method in comparison with the exact solutions available in the literature are: 1) it is less time-consuming and subsequently moreefficient; 2) it is able to analyze the free vibration of the beams whose section varies as an arbitrary function which is difficult or sometimes impossible to solve with analytical methods.

The effects of mismatch parameters on isochromatic fringe patterns were studied using the technique of photoelasticity. First, the mathematical equations of isochromatic fringes were derived for singular stress field near a bi-material notch. These equations were used to study the effects of mismatch parameters on the shape of isochromatic fringes theoretically. Analytical results indicated that the mismatch parameters have a significant effect on the shape of the isochromatic fringe patterns around the bi-material notch tip. In order to assess the accuracy of the analytical results, a photoelastic test program was conducted on the V-notched bi-material Brazilian disc specimens. A very good agreement was shown to exist between the experimental results and the analytical reconstructions.

Many supply chain problems are involved with different parameters, which are under uncertainties. One of the primary concerns on supplier selection is to handle the uncertainty under different circumstances. The primary objective of this paper is to design a model to select suppliers and to determine the amount of purchase from any supplier in the supply chain system. For this purpose, we select the most important criteria using fuzzy questionnaires where the questionnaire uses experts’ opinions in terms of linguistic values. Then, a hierarchy multiple criteria decision-making (MCDM) model based on fuzzy-sets theory is proposed to rank different suppliers and using a goal programming approach, we determine the amount of order product from each supplier. The implementation of the proposed model is demonstrated using a real-world case study.