Matej Borovinšek

Multi-objective optimisation model of shuttle-based storage and retrieval system

AbstractThis paper presents a multi-objective optimisation solution procedure for the design of the Shuttle-Based Storage and Retrieval System (SBS/RS). An efficient SBS/RS design should take into account multi-objectives for optimization. In this study, we considered three objective functions in the design concept which are the minimization of average cycle time of transactions (average throughput time), amount of energy (electricity) consumption and total investment cost. By also considering the amount of energy consumption as an objective function for minimization, we aimed to contribute to an environmentally friendly design concept. During the optimization procedure, we considered seven design variables as number of aisles, number of tiers, number of columns, velocities of shuttle carriers, acceleration/deceleration of shuttle carriers, velocity of the elevators lifting tables and acceleration/deceleration of the elevators lifting tables. Due to the non-linear property of the objective function, we ut...

Indirect Reconstruction of Pore Morphology for Parametric Computational Characterization of Unidirectional Porous Iron

This paper addresses the problem of reconstructing realistic, irregular pore geometries of lotus-type porous iron for computer models that allow for simple porosity and pore size variation in computational characterization of their mechanical properties. The presented methodology uses image-recognition algorithms for the statistical analysis of pore morphology in real material specimens, from which a unique fingerprint of pore morphology at a certain porosity level is derived. The representative morphology parameter is introduced and used for the indirect reconstruction of realistic and statistically representative pore morphologies, which can be used for the generation of computational models with an arbitrary porosity. Such models were subjected to parametric computer simulations to characterize the dependence of engineering elastic modulus on the porosity of lotus-type porous iron. The computational results are in excellent agreement with experimental observations, which confirms the suitability of the presented methodology of indirect pore geometry reconstruction for computational simulations of similar porous materials.

Optimisation of Product’s Hand-Handle Interface Material Parameters for Improved Ergonomics

Most authors have focused on the sizes and the shapes of the product handles, but neglected those interface materials of the handles, which could further improve the ergonomics of the product. Therefore we utilized optimisation method to determine optimal interface material properties of a product for optimal mechanical response of the system using numerical simulations of a fingertip model grasping a product’s handle. Objective function was set to find material parameters in such way that the interface material of the product stays firm during low grasping forces to provide stability of the product in hands and deforms when a critical contact pressure is reached to provide higher contact area. This increases comfort and lowers the contact pressure on the hand and thereby the risk of injury development.

Identification of Material Properties Through a Markov Chain Monte Carlo Technique and a Response Surface Approximation

In this work, the problem of identifying a set of model parameters to calibrate a simplified three-dimensional Finite Element (FE) model is addressed, by using data obtained from a three-point bending test. However, the expected computational cost of the forward problem hamper any attempt to perform the inverse analysis. To overcome this problem, the solution of the forward problem via FE is replaced by a metamodel based on a response surface approximation. The inverse problem is solved by using a Markov Chain Monte Carlo method. The proposed methodology reduces the computational cost by several orders of magnitude and results in estimates that allows to accurately reproduce both the synthetic data and the respective output of a FE simulation.