Karel Raz

Usage of Composite Materials in Design of Recuperative Member with Respect to Buckling Phenomena

This paper deals with composite materials usage in design of recuperative member. This member is designed as parallelogram and it is used as energy storage in winding device. This member consist of two linear springs, made from fibre-reinforced composite (carbon T700S with epoxy matrix MTM57). These two springs are mounted on both sides in aluminium brackets.

Dimension Stability of Thin-Walled Parts from 3D Printed Composite Materials

3D print of composite materials is one of the rapidly developing areas of additive manufacturing technology. This technology is using (instead of advanced FDM or SLA technologies) materials reinforced by short or micro fibres (mainly carbon or glass fibres). These fibres are oriented mainly in direction of filament extrusion. This is causing transverse- isotropic mechanical properties of final part. Composite materials with short fibres has higher modulus of elasticity, higher strength in bending, better thermal stability and higher impact resistance. These properties can be defined by change of volume rate between matrix and reinforcement. It is noticed nowadays, that these materials are more used in automotive and aerospace industry.

Tensile strength of various nylon PA6 specimen modes

This article explores the influence of production technique on the strength of nylon parts. Identical specimens were manufactured by various techniques. The material of specimens was nylon PA6. 3D printing and injection molding were used, with various orientations of printed layers, and various orientations of specimens in the working space of the 3D printer. The variants are described in detail. A special mold was used for the injection molding process in order to make specimens with and without a weld line. The effect of this weld line was evaluated. All specimens were tested using the standard tensile test configuration. The strength was compared. It was found that the same plastic material has very different mechanical properties depending on the production process.

Influences of pressures and cycle times on properties of final plastic product from HDPE

This paper deals with the possibilities of improving the quality of final product from plastic material. Advanced CAE simulation with finite element method was used as a tool for this research. Main aim of this article is to show procedure how to determine optimal level of injection pressure, packing pressure and times of all injection phases. All these parameters lead to improving of final properties of product. Wide range of values is given for each parameter and it is necessary to determine the suitable value. Exact influences of each parameter on the final product were detected with usage of CAE simulations of injection molding. All these dependencies were in article described. Research was focused on influence of all parameters on final product and also on technological process. Level of mold filling, number and size of weld lines, number of air traps and overall production times were chosen as main parameters for evaluation. Reference part is reinforcement profile from spoiler in racing formula car. Process with mean values of each parameter was chosen as a reference process. Influence were tested on product from high density polyethylene. Material properties for CAE simulation were clearly described in this article. All simulations were validated by experiment performed on real injection molding machine.

INFLUENCE OF HYDRAULIC PRESS COLUMNS CONNECTION ON DYNAMIC PROPERTIES

This paper deals with possibilities of hydraulic press design optimization. Dynamical loading is deeply discussed here. Technological operation called high speed forging is often used on this kind of machines. This technology leads to vibrations of whole hydraulic press. It must be ensured, that the lowest natural frequency of the whole press is higher comparing with frequency of forging. In research was performed finite element analysis, which showed influence of design modifications.