Vladimír Rusnák

Influence of Processing Parameters Production of Sandwich Composite Structures Designed Especially for the Construction of Machine Tool Parts

All components of a huge machine tool need to work together perfectly to ensure not only a quality finished product, but operator safety. One of those many components is the material of support panels and moving parts in the machine construction. Mechanical structure of the machine, in most cases does not reach the technical level of regulatory techniques or electric drives and potential increase in dynamics, speed or accuracy of the machines remain unused. Used classic construction materials, steel or light alloy then zoom in to limit their physical capabilities. Designers have machine tools or robots are forced to solve the formidable task in the form of reducing the weight of the moving parts while maintaining or even increasing stiffness with respect to the thermal stability or damping. Laminates are for construction of production machines, robots and manipulators of crucial importance. One big advantage is the high rigidity while maintaining low specific weight. The presented paper is focused on the investigation of composite sandwich construction produced by prepreg technology, which is the suitable production choose for construction of machine tools parts. First of all, the production of sandwich structures with cork core, honeycomb core and foam cores are compared and described. In terms of the production process it is a method very friendly to the environment, since there are no leaks styrene vapours into the air. Since it is important from the perspective of a manufacturer of transport or machine industry manufactured from environmentally friendly materials, so naturally from materials that are from the perspective of safety of passengers (operators of machine tools or robots) at a high level, when any accident was lowest possible hazard due to fire (burn materials used) and terms of the strength of composite materials. This is one of the major scientific articles and to find the most ideal surveyed composite sandwich materials that would be the greatest possible extent fulfils the required properties. In the experimental part of the article are compared and investigated the mechanical characteristics of composite sandwich structures with regard to varying number of layers of predimpregnated skin materials due to the different types of core materials suitable for use in the machine industry. In addition, these characteristics are an important part of the article research because described the influence number of layers to values of the bending stiffness those composite structures.

Thermal Properties of Sandwiches for Applications in Transportation

Composite sandwich structures are often used in the transportation industry as floors, roofs or parts of internal or external skeletons of buses, trains or trams. Compared to a monolithic composite there are a number of advantages which are apparent. Especially the low weight, higher rigidity, faster installation, better thermal insulation and good acoustic properties make it such an advantageous material. It is especially lower weight higher rigidity, faster installation, better thermal insulation and good acoustic properties. The paper deals with the measurement of the specific heat capacity, diffusivity and thermal conductivity of sandwiches differing in “core” material and a lining “skin” materials. As a “core” material the PET foam Airex T90.100, honeycomb type CORMASTER and natural cork material under the trade name CORECORK NL10 was used. As a coating phenolic prepreg and a composite material based on polyester/glass was used. All sandwiches under investigation have very low thermal conductivity as well as diffusivity.

Injection Moulding Versus Rapid Prototyping—Thermal and Mechanical Properties

This paper is devoted to the comparison of the influence of injection moulding (IM) on heat transport phenomena and the mechanical properties of materials, with rapid prototyping (RP). The tested materials included ABS and polyurethane (PU). The results show decrease of both mechanical properties and thermal transport phenomena in the case of RP samples.

Analysis of Mechanical and Impact Properties of Prepreg Composites under Elevated Temperature

This paper presents an experimental investigation of mechanical and impact properties of carbon and Kevlar-glass composites prepared from pre-impregnated materials. Namely, flexural performance in three-point bending at different temperatures is evaluated. Moreover, Charpy impact test and low-velocity impact test are also conducted for classification of impact properties and character of rupture. These all properties are important for material design of sport bike rims and many sport and other applications.

An Experimental Analysis of Bending Behavior of Sandwich Constructions for Transport Industry

In this work the mechanical performance of various sandwich constructions with respect to core material were experimentally evaluated. Sandwich structures were made of glass prepreg and three types of plastic core using vacuum bagging, technology traditionally used for production of parts for transport industry. The aim of this study is to analyze the impact of the core material type and its thickness on bending behavior at different environmental temperatures. Moreover, the effect of core layers compared to one layer core of same thickness was determined. Conducted research provided useful information of bending behavior and showed specific failure modes of individual sandwich constructions.

On Shearography Testing of Tires Separations

The paper deals with the systematic experimental study of tires wear accompanied by separation created in tires of different construction exposed to dynamic loading. 12 pieces of tires with the dimensions of 225/75 R 16 C with the same tread pattern were manufactured for the test in order to examine the impact on the material and design changes on the spread of separations in a tire. The atlas of separation is presented. The results of separation detection obtained by contact-less shearography are compared with those of optical. Graphic relevant analysis of tire wearing process is effectuated.

Lumped Capacitance Model in Thermal Analysis of Solid Materials

The paper is devoted to the presentation of a method for measurement of thermal conductivity k, specific heat capacity cp and thermal diffusivity α applying the lumped capacitance model (LCM) as a special case of Newtons model of cooling. At the specific experimental conditions resulting from the theoretical analysis of the used model, we present relatively very precise method for experimental determination of all three above mentioned thermal parameters for materials with different thermal transport properties. The input experimental data provide a cooling curve of the tested material obtained in special experimental arrangement. The evaluation of experimental data is realized by software the fundamental features of which are presented here. The statistical analysis of experimental data was performed (99% confidence interval P99).

Experimental Characterization of Multiaxial Glass Laminates for Front End Cab

This research paper deals with an experimental investigation of mechanical properties of prepared composite panels. Flexural behavior in three-point bending test is measured. Composites are prepared in order to satisfy requirements for transport industry. Totally, three material compositions are tested with different multiaxial reinforcing fabric and polyester resin. All samples are produced by low-pressure vacuum infusion mainly used for large-scale composite parts. Furthermore, fire resistance of prepared laminates is tested and appropriate classification into corresponding categories is also done. Experimental results proved suitability of prepared glass fiber composites for application in transport industry.

Experimental Study of Mechanical Behavior of HPL Composites

The paper provides experimental results from tensile and flexural tests of HPL composites. Mechanical properties of HPL laminates from four worldwide producers (Fundermax, Polyrey, Abet and Rexin) are compared. Composites are compared due to their stiffness and strength, both tensile and flexural. The exterior environment effect on mechanical behaviour of composites in service load conditions are presented too.

Infrared Monitoring of Inner Defects in Glass Laminates

In this paper, we present some distinguished methods of the digital thermograms software treatment which allows the visualization of hidden defects in glass fabric laminates, which are not usually visible in standard raw thermograms. The results of the software treatment are tested on artificial defects in glass laminate plates.