Project oriented courses became a global trend among best engineering universities around the world in the past decade. They teach students not only core academic knowledge, but face students with real problem solving situations, where they need to express and develop their other virtues and skills, e.g. working in multidisciplinary teams, time and task management, problem solving, different presentation and communication skills, etc. In this paper we investigate (multi-) cultural background of virtual team members from two different aspects: how it influences the team’s creativity and how various cultural backgrounds of creative team members could lead into different perceptions of particular design features. Multi-cultural background of NPD (New Product Development) teams is a complex challenge, which—if not addressed properly—could cause multi-level problems. The results of our first described research clearly indicate how these differences could affect the forming of virtual NPD creative teams and suggest guidelines how to build effective NPD teams. The second research shows that the same design features can trigger different responses in different cultural background. The designers, who design a product for a particular market, should be aware of these differences, which must be addressed with a special care if we want the product to be properly accepted at the desired target of a global market.
COBISS.SI-ID: 13944603
This paper presents a new accelerated testing procedure for plastic gears that is based on several different levels of testing. The iterative testing procedure fulfils requests from the product development process. The following criteria are considered for testing: reduced number of tests, shorter test time and reliable results for different applications. The proposed method was applied over the full range on a gear pair made from polyacetal (POM) and polyamide 6 (PA6). Different rotational speeds and torque loads, and therefore different transferred powers, were used for testing. During testing, gear temperature and cycles to failure were monitored. The paper also includes a comparison between the measured and theoretically calculated gear temperatures. A prediction of the life span on the basis of statistical methods is a part of the proposed test procedure. The presented procedure enables testing within acceptable cost and time consumption limits. The testing method can be reproduced and applied to plastic gears from different materials. Testing has shown that polymer gears fail in two typical ways: by fatigue and by sudden melting. The wear fail mode can be avoided by using an appropriate material pair. Fatigue can be measured by life span tests and is predictable. However, the melting of gears, which is a consequence of high gear temperatures, is not easily predictable. In most cases, melting failure mode occurs during the first few hours of gear testing. For reliable and optimal gear design, gear testing cannot be avoided because the tribological interaction between gears is specific for each combination of materials.
COBISS.SI-ID: 13733915
This work is focused on a parametric numerical study of the barrier\'s bar inclination shelter effect in crosswind scenario. The parametric study combines mesh morphing and design of experiments in automated manner. Radial Basis Functions (RBF) method is used for mesh morphing and Ansys Workbench is used as an automation platform. Wind barrier consists of five bars where each bar angle is parameterized. Design points are defined using the design of experiments (DOE) technique to accurately represent the entire design space. Three-dimensional RANS numerical simulation was utilized with commercial software Ansys Fluent 14.5. In addition to the numerical study, experimental measurement of the aerodynamic forces acting on a vehicle is performed in order to define the critical wind disturbance scenario. The wind barrier optimization method combines morphing, an advanced CFD solver, high performance computing, and process automaters. The goal is to present a parametric aerodynamic simulation methodology for the wind barrier shelter that integrates accuracy and an extended design space in an automated manner. In addition, goal driven optimization is conducted for the most influential parameters for the wind barrier shelter.
COBISS.SI-ID: 13859867
The main focus of this paper is the empirical modelling of the wear of carbon brushes. Rather than determining the dominant wear mechanisms, an approach towards the prediction of wear under a range of different conditions was used. The models were obtained by multiple regression analysis using lifetime (LT) data contributed by the biggest European manufacturer of vacuum cleaner motors. This included reliability data for 607 different test populations involving 3980 motors. Exploration of the data revealed that wear-out parameters behaved in accordance with the existing field theory, giving additional confidence to the models. The numerical appreciation of the wear-out parameters and the resulting conclusions will be beneficial to motor design and reliability engineers. Learned knowledge will be used for faster selection of optimal design and operational motor parameters to meet recent EU regulation 666/2013. Along with the more rapid design of the product, a reduced number of LT tests will result in significant energy savings.
COBISS.SI-ID: 13972251
Recent decades have seen research into the conditions necessary for the formation of the monotonic potential shape in the sheath, appearing at the plasma boundaries like walls, in fluid, and kinetic approximations separately. Although either of these approaches yields a formulation commonly known as the much-acclaimed Bohm criterion (BC), the respective results involve essentially different physical quantities that describe the ion gas behavior. In the fluid approach, such a quantity is clearly identified as the ion directional velocity. In the kinetic approach, the ion behavior is formulated via a quantity (the squared inverse velocity averaged by the ion distribution function) without any clear physical significance, which is, moreover, impractical. In the present paper, we try to explain this difference by deriving a condition called here the Unified Bohm Criterion , which combines an advanced fluid model with an upgraded explicit kinetic formula in a new form of the BC. By introducing a generalized polytropic coefficient function , the unified BC can be interpreted in a form that holds, irrespective of whether the ions are described kinetically or in the fluid approximation.
COBISS.SI-ID: 14168603