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Open access

P. Lacki, J. Adamus, W. Więckowski and J. Winowiecka

Abstract

Despite substantial demand for drawn parts made of high-strength sheet metal (including titanium alloys) observed in the modern industry, particularly automotive and aviation, their application remains insignificant. This results from the fact that such sheet metal shows poor plasticity and its cold-forming is almost impossible. Low drawability makes it impossible to obtain even such simple shapes as spherical cups. The authors of this study developed circular sheet-metal blanks with cutouts on their perimeter. The blanks allow for cold forming of spherical cups from Ti6Al4V titanium alloy sheet metal using conventional rigid tools. The cutouts proposed in the study affect plastic strain distribution, which in turn leads to an increase in forming depth by about 30%. The numerical analysis, performed using the PamStamp 2G System software based on finite element method, was verified experimentally.

Open access

Z. Pater and J. Kazanecki

Abstract

This paper presents the results of FEM simulations of the rotary piercing process in which disc guiding devices of the Diescher type are used. During this process the material is formed by means of two skew rolls, two guiding devices, and the piercing plug mounted on the mandrel. The aim of the analysis was to determine the effect of the plug diameter, the plug advance, the feed angle and the diameter reduction on the piercing process. Nine cases of piercing with three different plugs used were analyzed. The effects of the basic process parameters on the tube shell diameter and the tool load were analyzed. The numerical results obtained using Simufact.Forming 10.0 were verified under experimental conditions in which the tube shell made from 100Cr6 bearing steel was pierced. The results of the FEM calculations show agreement with the experimental results.

Open access

T. Pała and I. Dzioba

Abstract

The paper presents the results of two butt welded joints by conventional method. The welding process was performed using a variety of linear welding energy. The studies included experimental and computational part. In experimental studies determined the distribution of hardness and mechanical properties of the individual analyzed sections of welded joints. The data obtained were intended to determine the extent of zones in the welded joints that have certain strength characteristics. Also conducted uniaxial tensile tests of welded joints with the registration of displacement fields on the surface of specimens by means of Aramis video-system what the final result are images of strain fields map on the surface of welded joints. The resulting strain values were compared with the results of numerical computations FEM.

Open access

W. Barnat

Abstract

This paper presents experimental and numerical studies on influence of an incidence angle of the shock wave on a steel plate. The problem of interaction between the wave front and a barrier is important from the point of view of protection the crew of armored vehicles. One way of remedying the harmful effects of impacts of the shock wave is the reflection wave of the barrier set at an angle to the face of the wave. The article presents the numerical and experimental approach to the subject. The numerical part presents four models in which the plate was set at angles 0◦, 15◦, 30◦, 45◦. In each case, the plate was loaded by a wave formed after the explosion 2 kg of TNT. In the experimental part the results are presented from an experiment in which the wave was formed from 2 kg TNT detonation at a distance of 0.4 m in parallel to the steel plate.

Open access

J. Bartnicki, J. Tomczak and Z. Pater

Abstract

This paper presents results of numerical calculations for the rolling process by means of three tools of stepped shafts from aluminum alloy 7075. Forming with the usage of tools with three different wedge spreading angles underwent analysis. In the paper, the obtained distributions of stresses, strains and Cockcroft-Latham damage criterion were given. Moreover, the influence of the wedge spreading angle on shape faults presence in the obtained product was determined. At the same time, the force parameters, which play a crucial role in the designed experiment, were analyzed.

Open access

M. Kukuryk

Analysis of Deformation and Damage Evolution in Hot Elongation Forging

The paper describes the analysis of the three-dimensional stress and strain state for the process of elongation forging of the X37CrMoV51 die steel using the finite element method. The results of simulation studies of the metal flow pattern and thermal phenomena in the hot forging process carried out in three different forging tools are reported. The results of the studies have been complemented with the prediction of the occurrence of ductile fractures during forging. The numerical analysis was performed using the DEFORM-3D program. The comparison of the theoretical study and experimental test results indicates a possibility of applying the developed model to the examination of strains and prediction of material fracturing during the hot forging of die steel.

Open access

Vasile Nastasescu, Ghita Barsan and Oana Mocian

Abstract

The foam materials, by construction and by characteristic properties (low density, large deformations, great flexibility, Poisson ratio practically zero etc.), are widely used in many and various domains. The numerical simulation of the foam material behavior raises some difficulties, which can be impassable under certain circumstances. This paper presents some of our researching results in numerical modeling of foam materials, which can be very useful for those interested in numerical modeling of the foam materials. Numerical modeling used by the authors is based on the finite element method (FEM) and on the element-free Galerkin (EFG) method. The results are presented in a comparatively way and they also present how some usually running errors can be avoided. The conclusions and the results are considered by the authors very useful in modeling of the foam materials and in choosing of the most fitted method too.

Open access

Łukasz Gołuński and Bolesław Augustyniak

Modeling by finite element methods of impact of erosion on frequency of normal modes of l-0 blade

After some time of exploitation steam turbine rotors blades in energetic industry they are being eroded and also their frequency of normal modes is changed. Those changes can cause to unwanted shift of blades normal mode frequencies. It is necessary to find quick method of rating changes of frequency in connection of mass loss due erosion. The evaluation of this dependence was made by finite element modeling method using HyperWorks 8.0 software. Geometrical model of blade L-0 with mass of 22 kg and length of 74 cm was used. There were calculated frequencies of the first five modes in function of mass loss along the leading blade edge (up to mass loss of 1,2%). Small losses of weight (around 0,2%) cause similar changes in values (around 0,2%) for all modes but with different types of frequency change (decrease or increase). The frequency decreases for all modes except mode the 3rd. For bigger mass loss an monotonic decrease of frequency was observed in 1st, 2nd, 5th mode and maximum (around +1,5 %) for 3rd mode and minimum (- 0,5%) for 4th mode. For maximum mass loss (1,2%) maximal decrease of frequency was observed in 2nd mode around -2%. Results of this modeling can be used to estimate changes of frequencies caused by erosion in exploited blades when their mass loss is known.

Open access

Mehdi Koohmishi

Abstract

In this paper, a comparison between pavement responses is performed by considering two different models for the linear viscoelastic behavior of an asphalt concrete layer. Two models, the Maxwell model and the Kelvin-Voigt model, are generalized. The former is used in ABAQUS and the latter in KENLAYER. As a preliminary step, an appropriate structural model for a flexible pavement structure is developed in ABAQUS by considering linear elastic behavior for all the layers. According to this model, when the depth of a structural model is equal to 6 meters, there is a good agreement between the ABAQUS and KENLAYER results. In this model, the thickness of the pavement is equal to 30 centimeters, and the thickness of the subgrade is equal to 5.7 meters. Then, the viscoelastic behavior is considered for the asphalt concrete layer, and the results from KENLAYER and ABAQUS are compared with each other. The results indicate that the type of viscoelastic model applied to an asphalt concrete layer has a significant effect on the prediction of pavement responses and, logically, the predicted performance of a pavement.

Open access

N. Nikolov, T. Avdjieva and I. Altaparmakov

Abstract

Some specially designed metallic alloys crystallize during process of rapid quenching which aims their amorphization. Nevertheless, change in their mechanical properties could be seen compared to these obtained during conventional technological regimes of cooling. That attracts the attention in this elaboration. Full 3-D numerical simulations of nanoindentation process of two material models are performed. The models reflect equivalent elastic and different plastic material properties. The plastic behaviour of the first one is subjected to yield criterion of Dracker-Prager and this of the second one to yield criterion of Mises. The reported numerical results depending on the nanoindentation scale length of 1000 nanometers, suggest different adequacy of the two yield criteria to the data obtained experimentally with a Zr-Al-Cu-Ni-Mo alloy. It could be speculated that the different effects developed depending on the indenter travel of 1000 nanometers and taken into account in the two yield criteria stand behind this fact and determinate three structural levels of plastic deformation.