Aleš Lufinka

Analysis of the Tailgate Frame Composite Tube Mechanical Properties

Substitute of the traditional materials with new plastic-based and composite materials is a trend in todays automotive industry. Mechanical properties of the composite parts are highly influenced by the composite production (material of fibers and their distribution, type and density of a filler). Knowledge of the specific composite material mechanical properties is necessary for CAD modeling and FEM calculations during the assembly design. These mechanical properties can be obtained by creating a composite structure in FEM software. However, the real composite may be different from the ideal FEM model (due to inaccuracies in its manufacture). Therefore, it is highly advisable to verify the modeling results by measuring of the real composite material properties. Identification and verification of the composite tube mechanical properties used in the hybrid car tailgate are described in this paper.

Hydraulic Exciter Control for Shock and Vibration Testing

The important part of the validation and certification of the new product are vibration and shock testing of mechanical, electrical and electronic equipment components that are mounted on rail vehicles. The hydraulic shaker is possible to use as the vibration and shock exciter to simulate the effect of the environment to the specimen. It is necessary to fulfil the prescribe condition of the level of mechanical vibration and the acceleration peak of the shock test signals. The specific hydraulic motor produced by INOVA is designed for the specific vibration test and the aim is to use it also for the shock tests. The control algorithm uses two iteration methods in time and frequency domain and their use depends on test prescription.

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.

Testing of Space Frames Made of Composite Materials

Innovative development and production trends particularly in automotive and aerospace industries significantly influence also design of opening panels assemblies (doors, windows, stiffened panels etc.). New trends show that metal constructions of these modules will be gradually replaced by new material conceptions leading to hybrid plastic material-composite-metal constructions. This fact is logically reflected by methods and methodologies in testing, used both in pre-development, prototype and finally even in batch phase of the development and production. The main topic of the paper deals with presentation of several testing devices and used measurement methods for testing of qualitative parameters of rigidity and strength of both the whole module groups and their fundamental reinforcing components made of composite materials.

Experimental Analysis and Study of the Shock Absorption of Carbon Composite

Composite materials are a regular part of many industries - aerospace, automotive, mechanical engineering. Lower weight and comparable in some ways even better mechanical properties, are the reason why composites progressively substitute traditional metal based material. The article describes the design of composite tub with metal reinforcement. Compares the theoretical and real output of sample produced from CF prepreg specially designed for absorbing the energy during crash impact. The results show that the sample due to its deformation is able to absorb some energy and become a material usable in structural applications.

Measuring Device for the Cutting Parameters Monitoring during Drilling

A drilling process quality and a drill life depend on the cutting conditions optimal setting. Research in the area of cutting fluid composition and drilling tools parameters for nonstandard material setting is performed at Technical university of Liberec. Real drilling parameters monitoring is essential during this research. Axial force and torque are two basic parameters describing this process. The measuring device for these parameters monitoring which was built at Technical university of Liberec is described in this paper.

Numerical Modelling and Experimental Measurement of Lifting Platform Construction for Car Relocation

Numerical modelling and experimental measurements led to the assessment of stress of structural nodes of scissor lifting platform, which is used for relocation of cars from a production line. It also led to optimization of producing process. Immediate load of scissor lifting platform by a car on stand causes additional bending moment that must be captured in a scissor mechanism. At the beginning the experimental measurements on the real lifting platform were made for obtaining of dependence of displacement, velocity and acceleration on time which was almost 1.5±0.1 g. Then dynamical analysis using a numerical method Runge Kutta 4th order of lifting platform were created. Model analysis showed that the initial immediate acceleration of lifting platform at start and immediate deceleration at stop lead to dynamic shocks. These dynamic shocks are due to long term operation dangerous because they permanently load not only pivots but also other parts – bearings and joining parts. A resonance may occur as well. In particular, dynamic shocks caused damage of structural nodes. Immediate load of scissor lifting platform by a car on stand causes additional bending moment. It is not appropriate in terms of long-term operation. Recommended load lifting platform should be symmetrical.

Dynamic Analysis of Lifting Platform Construction for Car Relocation

For a force assessment which acts in individual parts of a scissor lift platform for moving of cars from the production line a dynamic analysis and experimental studies were performed. The analysis of loads show that immediate loading of platforms by the car causes additional bending moment that must be captured in a scissor mechanism. Initially experimental measurements were carried out on the real platform for obtaining of trajectory, velocity and acceleration. Subsequently, model analysis of the lifting platform using four point Runge-Kutta method, were assembled. The model analyzes found that a step loading during acceleration and deceleration of the platforms leads to a dynamic impact that are unsafe due to long term use. The consequence of said is repeated overloading of pivots, bearings, fittings and other parts. Also the dynamic stress may be accompanied by the resonances.