Emil Spišák

The Experimental Analysis of Forming and Strength of Clinch Riveting Sheet Metal Joint Made of Different Materials

The paper presents the pressed joint technology using forming process with or without additional fastener. The capabilities for increasing the load-carrying ability of mechanical joints by applying special rivets and dies were presented. The experimental research focused on joining steel sheet metal made of different materials. The joint forming was performed with the solid round die and rectangular split die for riveted joint forming. The load-carrying ability of joints was evaluated by measuring the maximum load force in the shearing test in the tensile testing machine. The effect of joint forming process on joined material strain was compared by measuring the microhardness of the joints.

Experimental and Numerical Analysis of Local Mechanical Properties of Drawn Part

In this study, numerical and experimental results of deep drawing process were compared. Drawn part, used in automotive industry was drawn and measured using ARGUS measurement system, which works on a digital image correlation method (DIC). In order to optimize and verify accuracy of a numerical simulation results, this process was modeled in two codes which work on principle of the finite element method (FEM). Two types of FEM codes were used. Code which works on base of both, implicit and explicit time integration scheme, were used for calculation. Results were compared and discussed.

Usage of Neural Network to Predict Aluminium Oxide Layer Thickness

This paper shows an influence of chemical composition of used electrolyte, such as amount of sulphuric acid in electrolyte, amount of aluminium cations in electrolyte and amount of oxalic acid in electrolyte, and operating parameters of process of anodic oxidation of aluminium such as the temperature of electrolyte, anodizing time, and voltage applied during anodizing process. The paper shows the influence of those parameters on the resulting thickness of aluminium oxide layer. The impact of these variables is shown by using central composite design of experiment for six factors (amount of sulphuric acid, amount of oxalic acid, amount of aluminium cations, electrolyte temperature, anodizing time, and applied voltage) and by usage of the cubic neural unit with Levenberg-Marquardt algorithm during the results evaluation. The paper also deals with current densities of 1 A·dm−2 and 3 A·dm−2 for creating aluminium oxide layer.

CLINCHRIVET AS AN ALTERNATIVE METHOD TO RESISTANCE SPOT WELDING

Abstract Various materials are used in car body production which are not always possible to join by conventional joining methods such as resistance spot welding. Therefore ClinchRivet method seem to be possible alternative. The paper deals with evaluation of properties of the joints made by mechanical joining method - ClinchRivet. The joint is made with the using of a special rivet, which is pushed into the joined materials by the flat punch. Following materials were used for joining of this method: DX51D+Z and H220PD steel sheets. The tensile test for observing the carrying capacities and metallographicall analysis were used for the evaluation of joint properties. Some results of the tests of ClinchRivet joints were compared to the properties of the joints made by resistance spot welding.

FEM Analysis of Clinching Tool Load in a Joint of Dual-Phase Steels

The clinching tool with a die of 5 mm diameter with a specially formed gap and a punch of 3.6 mm diameter were used for mechanical joining of dual-phase steel sheets DP600 with the pressing force of 30 kN. The punch and die were deposited by PVD coating of CrN type with LARC technology. The coating state of each 50th manufactured joint was evaluated by SEM. Cracks in the area of punch’s radius were detected. The finite element method was applied for the assessment of punch load in the joining process.

Optimization of FDM Prototypes Mechanical Properties with Path Generation Strategy

This paper present result of a study evaluating the influence of path generation strategy on mechanical properties of Fused Deposition Modeling (FDM) prototypes. Several scientific studies were researching the problematic of path generation and internal structure of FDM prototypes. Mostly the influence on mechanical properties was observed. This paper is aimed on determine the influence of outline number and internal air-gap on tensile strength of parts built from ULTEM 9085. For this two variables was determined the influence on built time and consumption of modeling material. Result show that proper model orientation when the orientation of load is known, can help to reduce the build time and material consumption.

Effect of the Electrolyte Temperature and the Current Density on a Layer Microhardness Generated by the Anodic Aluminium Oxidation

The paper investigates the influence of the chemical composition and temperature of electrolyte, the oxidation time, voltage, and the current density on Vickers microhardness of aluminium oxide layers, at the same time. The layers were generated in the electrolytes with different concentrations of sulphuric and oxalic acids and surface current densities 1 A·dm−2, 3 A·dm−2, and 5 A·dm−2. The electrolyte temperature varied from −1.78°C to 45.78°C. The results have showed that while increasing the electrolyte temperature at the current density of 1 A·dm−2, the increase in the layer microhardness values is approximately by 66%. While simultaneously increasing the molar concentration of H2SO4 in the electrolyte, the growth rate of the microhardness value decreases. At the current density of 3 A·dm−2, by increasing the electrolyte temperature, a reduction in the microhardness of the generated layer occurs with the anodic oxidation time less than 25 min. The electrolyte temperature is not significant with the changing values of the layer microhardness at voltages less than 10.5 V.

Flexural Properties of FDM Prototypes Made with Honeycomb and Sparse Structure

The rapid prototyping (RP) process is capable of building parts of any complicated geometry in least possible time without incurring extra cost due of absence of tooling. Fused deposition modeling (FDM) is a fast growing RP technology due to its ability to build functional parts having complex geometrical shape in reasonable time period. The quality of built parts depends on many process variables. The presented study focus on assessment of mechanical property flexural strength of part fabricated using fused deposition modeling (FDM) technology. The 3-point bending test was used, to determine flexural strength. Samples were made of polycarbonate on Fortus 400 mc machine from polycarbonate with slice height 0.127mm. The experiment was focused on influence of air-gap size between fibers and number of outline contours on selected mechanical properties of FDM prototypes determined 3-point bending test. The results show possibility to obtain weight reduction in printed parts with sparse structure with sufficient flexural strength and with reduced build time, compared to structure printed with default machine setting,. To obtain optimal processing parameters for 3D printing prototypes, it is necessary to execute further experiments, which could verify gathered results.

Local Strain Hardening and Non-Uniformity of Plastic Strain of Tinplate

During evaluation of the mechanical properties of tinplate for packaging industry by uniaxial tensile test, a non-uniform plastic strain occurs very often. This phenomenon results from the fact, that the plastic deformation is not uniformly developed throughout the measured section. There is a localization of deformation in one or more places resulting in local changes of the tinplate ́s mechanical properties. This paper deals with local strain hardening and non-uniformity of plastic strain of the tinplate temper TH415CA during uniaxial tensile test. Based on micro hardness measurements in the following locally deformed areas, local changes of mechanical properties of the tinplate were determined. The reasons of early strain localization were assumed by microstructural analysis. In the present work are considering partial aspects of the problem focusing on the properties of the local strain hardening and their consequences for stability of uniform plastic strain.

Effect of Welding Parameters on the Quality of Spot Welds Combining AHSS Steel and HSLA Steel

The resistance spot welding of dissimilar materials is generally more challenging than that of similar materials due to differences in the physical, chemical and mechanical properties of the base metals. Advanced high strength steels and high strength low alloy steels are utilized in automotive industry to reduce weight of the vehicle body and consequently lowering the fuel consumption to achieve the lowest possible fuel consumption, high active and passive safety of passengers while decreasing the amount of emission. The influence of the primary welding parameters, especially welding current, microhardness and tensile shear load bearing capacity of dissimilar welds between TRIP 40/70 as an Advanced High Strength Steel and H220PD as a High-Strength Low-Alloy steel has been investigated in this paper.