Krzysztof Kluger

Residual Stresses in Steel-Titanium Composite Manufactured by Explosive Welding

The main aim of the paper is determination of residual stresses in explosively welded steel-titanium bimetal. The analysis considers two bimetallic specimens: before and after the heat treatment. In residual stress determination the hole drilling method along with finite element analysis were applied. The results show different residual stress states depending on the heat treatment. The obtained results are confirmed by thermal stress calculation.

Low cycle fatigue of steel in strain controled cyclic bending

Abstract The paper presents a comparison of the fatigue life curves based on test of 15Mo3 steel under cyclic, pendulum bending and tension-compression. These studies were analyzed in terms of a large and small number of cycles where strain amplitude is dependent on the fatigue life. It has been shown that commonly used Manson-Coffin-Basquin model cannot be used for tests under cyclic bending due to the impossibility of separating elastic and plastic strains. For this purpose, some well-known models of Langer and Kandil and one new model of authors, where strain amplitude is dependent on the number of cycles, were proposed. Comparing the results of bending with tension-compression it was shown that for smaller strain amplitudes the fatigue life for both test methods were similar, for higher strain amplitudes fatigue life for bending tests was greater than for tension-compression.

The Effect of the Detonation Velocity in Explosively Welded Steel-Zirconium Bimetal on the Residual Stresses Determined by the Hole-Drilling Method

As a result of the explosion welding, residual stresses are generated in the cladded material which can affect the properties of the bimetallic composite. This paper analyses the value of residual stresses in the steel-zirconium bimetal sheets, for which the detonation velocities were 1,0V0 (where V0 = 2200m/s); 1,3V0 and 1,6V0 with constant others welding parameters.

Comparison of 15Mo3 Strain Curves Obtained for Strain-Controlled Cyclic Bending and Tension-Compression Tests

The paper presents a comparison of the fatigue life curves based on test of 15Mo3 steel under cyclic, pendulum bending and tension-compression. These studies were analyzed in terms of a large and small number of cycles where strain amplitude is dependent on the fatigue life. It has been shown that commonly used Manson-Coffin-Basquin model cannot be used for tests under cyclic bending due to the impossibility of separating elastic and plastic strains. For this purpose, some well-known models of Langer and Kandil and one new model of authors, where strain amplitude is dependent on the number of cycles, were proposed. Comparing the results of bending with tension-compression it was shown that for smaller strain amplitudes the fatigue life for both test methods were similar, for higher strain amplitudes fatigue life for bending tests was greater than for tension-compression.

Mean Stress in Algorithms Estimating Fatigue Life of Selected Structural Materials

The paper presents comparison of the mathematical models for fatigue life calculations including influence of the mean load value. Several model based on stress analysis on the critical plane and energy density parameter were investigated. In this paper three types of materials were tested and subjected to bending, torsion and combination of bending with torsion loading with the participation of mean value of the load. It was found, that the best fatigue life estimations obtained by models taking into account changes of the material behavior under fatigue loading related to the specified numbers of cycles of the load.

Modification of the fatigue life calculation algorithm for criteria based on the critical plane concept

The aim of this paper is to propose an algorithm for the calculation of the fatigue life using commonly known material fatigue criteria, including the correct determination of the material parameters being the function of the number of cycles to failure. The paper presents the application of the modified algorithm to the Findley and Papadopoulos criteria and the comparison of the results of calculations to the results of the experiment for steel S355J2G3 and Ck45. In case of both analysed materials, the application of the modified algorithm in fatigue criteria allowed to obtain much more accurate results of calculations for all of the analysed types of loadings. In case of the evaluation of the fatigue life for steel S355J2G3, better results were obtained using the Findley criterion whereas in case of steel Ck45 – the Papadopoulos criterion.