Pavel Srb

Testing of Tensile Properties of Carbon Prepreg Composite Rods with Adding of a Non-Composite Part

The global development of carbon composite materials has been devoting constantly in still more companies and research institutions. Pre-saturated fabrics known as prepregs have a significant position in this field. The common problem of many worldwide authors is how to determine their tensile strength. The problem with tensile load is mainly due to the extremely high strength of fibers filaments and structural fragility of the thin width of formed profiles. Therefore, indirect methods are usually used. They are based on a determination of the resonant frequencies or on a conversion of values obtained e.g. with bending test. In our case, some experiments have been based on the idea of added a non-composite material into the final structure. The aim of this work was also to find an appropriate modification of a surface of the additional element with regard to a mutual interaction, surface microstructure and mechanical properties of the resulting composite part.

Experimental and Numerical Analysis of Stress and Stick-Slip Effect of the Test Stand

Experimental and numerical analysis describes the design of noise removal effect of the friction pair of trapezoidal screw in a special device call Stick-Slip effect. Solution of the problems builds on previous measurements and testing sliding pairs, which was testing in last analysis. The pair worked in the special bath oil, its characteristics is that it does not support the mechanical lubrication. Measurements and calculations showed that it is necessary to enlarge the diameter for 32 kN load trapezoidal screw. This will reduce the contact pressure, which leads to polish the contact surfaces. You then slip together better and are not as easily stick slip effect.

Study of Mechanical Properties and Modeling of Flax Reinforced Composites

This article deals with assessment of mechanical properties and possible technical usability of flax prepreg composite materials. Mechanical properties of materials are the decisive factor for selection of their suitable industrial application. The main step was to describe the process of acquiring basic mechanical properties of one layer. Then, these properties were used for creation of a numerical model of a primary laminate and subsequently for modeling a multilayered composite. The performed FEM model has been verified based on the experimentally tested samples in tensile and flexural loading.

Development of fire shutters based on numerical optimizations

This article deals with a prototype concept, real experiment and numerical simulation of a layered industrial fire shutter, based on some new insulating composite materials. The real fire shutter has been developed and optimized in laboratory and subsequently tested in the certified test room. A simulation of whole concept has been carried out as the non-premixed combustion process in the commercial final volume sw Pyrosim. Model of the combustion based on a stoichiometric defined mixture of gas and the tested layered samples showed good conformity with experimental results – i.e. thermal distribution inside and heat release rate that has gone through the sample.

Cam Mechanism for Car Seat Testing

This paper deals with optimization of a device designed for long-term dynamic testing of car seats. This kind of tests is important for car seat innovation with respect to improving safety and comfort of passengers. This type of testing is based on linear periodic movement of a car seat cushion on which a weight representing a passenger is placed. Movement of seat is generated by a cam mechanism. Several cam profiles were proposed by a computational software, in order to achieve acceleration occurring during a real car driving. Based on this information concept of the whole device was proposed. Thereafter the static and dynamic FEM analysis were carried out. Finally an optimization of the cam mechanism and the whole device was accomplished in order to achieve the best compromise of conflicting requirements of large acceleration at low frequencies.

Experimental Analysis and Optimization of Vibrations of a Clamping Device by Using Hyperelastic Elements

Nowadays composite frames can be used, for its specific properties, in many fields of industry. Lightweight composite frames can be significant structural components in some transportations, flights and military applications. The main problem is how to use automatic applications for winding filaments of the carbon fibres on a closed spatial shaped core of product frames, that has been still doing by the hand manufacturing. For automatic production could be used unique prototype of robotic technology, which allows winding of the carbon fibres on closed shape into the core of a frame. The biggest problem of the clamping device, used for the closed frames, are their vibrations and resonance caused due to the rotary motions. The vibrations and resonance negatively affect the process of carbon fibres winding. Experimental measurements were carried out to determine the acceleration on individual arms of the clamping device, which reaches to 2.5±0.6 g. Minimizing of the vibration was performed by a hyperelastic elements which reduce vibrations to 0.4±0.15g.