Maja Trstenjak, Tihomir OpetukIndustry 4.0 Readiness Factor Calculation and Process Planning: State-of-the-Art Review

Process planning is confronting changes in terms of Industry 4.0. If the strategy and the investment plan are not defined properly, changes might cause loss. This emphasizes the importance of the readiness factor calculation. The factor expresses the current stage of development and enables the definition of a plan of action with respect to a goal. This paper gives a state-of-the-art preview of existing readiness factor calculation methods both within scientific and commercial approaches. Relation between the Industry 4.0, process planning and readiness factor calculation methods is examined and the scientific gap in the field is detected. This has enabled to create a framework of the new readiness factor calculation method, specialized for process planning in Industry 4.0.

Key words: process planning; industry 4.0; readiness factor; smart factory

Rahmath Ulla Baig, Shaik Dawood, Mohamed Mansour, Tarik Tawfeek: Identifying and Prioritising Future Robot Control Research with Multi-Criteria Decision-Making

The gap between researchers who carry out scientific exploration and practitioners who can make use of the research results is well known. In addition, while practitioners place a high value on research, they do not read many research papers. This paper attempts to define and prioritise future research in robotics using the analytical hierarchy process (AHP). Fifteen research alternatives and gaps, five performance criteria, eight industry types, and six production processes, investigated by both academics and practitioners, are filtered to six alternatives, four performance criteria, three industry types, and three production processes, respectively, based on the most important factors in decision-making. Subsequently, they are analysed by the Expert Choice software. This research aims at bridging the gap between academics and practitioners in robotics research and at conducting research that is relevant to industry. The results indicate that the research in multi-robot control ranked first with 26.8%, followed by the research in safe control with 23.3% and the research in remote robot supervision with 19.0%. The research in force control ranked fourth with 17.8%, followed by the research in 3D vision and wireless communication with 8.4% and 6.4%, respectively. Based on the results, the academics involved in robotics research should direct their effort to the research activities that received the highest priority in the AHP model.

Key words: future research in robotics; multi-criteria decision-making; analytical hierarchy process; qualitative analysis

Nenad Petrović, Vesna Marjanović, Nenad Kostić, Nenad Marjanović, Mircea Viorel Dragoi: Means and Effects оf Constraining the Number of Used Cross-Sections in Truss Sizing Optimization

This paper looks at sizing optimization results, and attempts to show the practical implications of using a novel constraint. Most truss structural optimization problems, which consider sizing in order to minimize weight, do not consider the number of different cross-sections that the optimal solution can have. It was observed that all, or almost all, cross-sections were different when conducting the sizing optimization. In practice, truss structures have a small, manageable number of different cross-sections. The constraint of the number of different cross-sections, proposed here, drastically increases the complexity of solving the problem. In this paper, the number of different cross-sections is limited, and optimization is done for four different sizing optimization problems. This is done for every number of different cross-section profiles which is smaller than the number of cross-sections in the optimal solution, and for a few numbers greater than that number. All examples are optimized using dynamic constraints for Euler buckling and discrete sets of cross-section variables. Results are compared to the optimal solution without a constrained number of different cross-sections and to an optimal model with just a single cross-section for all elements. The results show a small difference between optimal solutions and the optimal solutions with a limited number of different profiles which are more readily applicable in practice.

Key words: truss optimization; cross-sections; Euler buckling; sizing; optimization constraints

Andrzej Kubit, Wojciech Jurczak, Tomasz Trzepiecinski, Koen Faes: Experimental and Numerical Investigation of Impact Resistance of Riveted and RFSSW Stringer-Stiffened Panels in Blunt Impact Tests

Aluminium alloy sheets have come into widespread use in the design of stringer-stiffened aerospace structures. This paper evaluates experimentally and numerically the response of stringer-stiffened Alclad 7075-T6 aluminium alloy panels subjected to impact loading. The aim of the study was to compare the impact resistance of riveted structures with the structures with the impact resistance of structures welded using the refill friction stir spot welding (RFSSW) process, which is a relatively new technique now used to create joints in aircraft structures. The experimental tests were carried out using a drop-weight type impact testing machine. Finite element modelling of stringer-stiffened panels under impact loading was carried out by using the nonlinear finite element-based MSC.Marc + Mentat program. The results of the numerical computations were validated against the experimental data. Studies were also made of the resistance of the joints to failure, the springback response and the stiffness of joints in the conditions of the dynamic impact test.

Key words: blunt impact test; FEM, impact resistance; RFSSW; stiffened panel

Rong Li, Quanzhao Sun, Jie Zhang, Yanming Song, Guolai Yang, Baochun Lu: Multiple Attribute Decision Making with Interval Uncertainty for Artillery Recoil Resistance

To reduce loads acting on artillery carriages and obtain better values of recoil resistance, a study on multiple attribute decision making with interval uncertainty of the liquid orifice of a recoil mechanism was conducted. Taking the dimensions of the liquid orifice as the uncertainty variables, the uncertainty optimization model and algorithm based on three parameter interval were used to achieve the optimization schemes of the throttling bar outer dimensions with different tolerance grades. The multiple optimization schemes were sorted by employing the multiple attribute decision making method, in which the attribute weights were determined based on the maximum deviation method. The results show that the optimal design scheme is the one which considers simultaneously the parameter design and tolerance design of the throttling bar outer diameters. The optimal interval of the recoil resistance peaks and the optimal recoil resistance curve with sufficient fullness and flatness were obtained. The study results are beneficial for artillery design and evaluation concerning both the manufacturability of artillery and particular requirements of recoil resistance.

Key words: Artillery recoil resistance; multiple attribute decision making; interval uncertainty; optimization evaluation; uncertainty of dimensions

Ivana Mikušová, Pavol Mikuš, Jiří Stodola: The Effect of Mechanical Properties of a Rubber Compound on Tyre Wear

This article deals with the effect of mechanical properties of a rubber compound on tyre wear. For detection purposes, samples of thirteen types of rubber compounds were made, used, and processed in practice. Their hardness was measured with an IRHD (International Rubber Hardness Degree) hardness tester; tensile strength and ductility measurements were carried out at a universal testing facility, Instron 4466. A rapid wear test was conducted on a roller abrasive machine. All measurements were assessed and compared. Selected original results are listed in this article.

Key words: tyre; wear; hardness; effect; test sample

Erdinč Rakipovski, Dragan Milčič: Validation Testing of an Innovative Braking System for Freight Wagons

In this study, validation tests have been conducted on an innovative braking system for freight wagons. The paper presents the results of the tests, which are crucial for the approval of the braking system. Considering that the braking system is of great importance for the safety of rail transport and that it is exposed to high static and dynamic loads in external conditions, a series of tests were carried out to validate the braking system. The testing of the braking system was carried out on specialized test tracks in order to check if the technical requirements are met. The results from the validation tests of the innovative braking system are positive.

Key words: braking system; freight wagons; stand; testing

Modi Manoj, Agarwal Gopal: Modelling, Investigation of Process Responses, Surface Assessment and Parametric Optimization in Powder Mixed Electrical Discharge Diamond Grinding of TI6AL4V Utilizing Grey-Based Taguchi Approach

In this study, the powder mixed electrical discharge diamond grinding (PMEDDG) process was designed and a set-up for machining hard electrically conductive material surfaces built. The paper presents empirical models, investigation, an optimal setting of factors and the distinct surface production in the PMEDDG of Ti6Al4V with aluminium (Al) and silicon carbide (SiC) powder mixed dielectric fluid. The response surface methodology was applied to the modelling. One set of 32 experiments with Al powder and another set of 32 experiments with SiC powder mixed dielectric fluid were performed on a PMEDDG set-up. Current, pulse on time, wheel speed, duty cycle, and volumetric proportion of the powder were taken as input machining variables. Material removal rate and surface roughness were computed as outputs. The behaviour of the input factors against the responses was studied and compared with the SiC and Al powder mixed dielectric fluid used in the PMEDDG process. Further, scanning electron microscopy (SEM) investigations were carried out to determine the impact of different factors on the PMEDDG-produced surfaces as well as the effect of powder presence in the dielectric fluid on white recast layer thickness of the produced surfaces. The grey-based Taguchi approach was used to determine an optimal set of process variables when aluminium powder is used and a confirmation test was conducted on the optimal set to estimate the effectiveness of this approach.

Key words: powder mixed electrical discharge diamond grinding; analysis of variance (ANOVA); grey-based Taguchi approach; hybrid process; RSM; SEM; Ti6Al4V