Applied Mechanics and Materials Vol. 784

Abstract: The austenitic cladding of the WWER pressure vessel is made from two different layers with different fracture toughness values. Based on the fractographic analysis of the tested specimens in the initial, as well as in the irradiated conditions, it was found that individual failure micromechanisms take place during the crack propagation. The obtained results were used to find the relationship between the failure micromechanism changes and the fracture toughness values, as well as to assess the effect of neutron irradiation on the failure micromechanisms.

Abstract: In the civil and structural engineering field, there are so many problems regarding act of impact loading against some structures due to natural disaster. So it is important to evaluate the damage condition of them after impact loading, and to estimate the residual performance of them. This study is focused on a reinforced concrete (herein after called RC) structure such as caisson breakwater and rock-shed. In order to quantitatively evaluate the dynamic behavior and cumulative damage of RC members under low-velocity single and repeated impact loading, we conducted numerical approach by using the theory of Continuum Damage Mechanics (herein after called CDM). At the result, we clarified not only impact behavior of the members but also the relationship between cumulative kinetic energy of repeated impact loading and cumulative damage of the members. In addition, applicability limit of our model based on scalar damage modeling was clarified.

Abstract: In order to study the influence of freezing and thawing on the dynamic behavior of ceramsite concrete, specimens with four kinds of ceramsite volume fraction including 0%, 15%, 30% and 45% which subjected to 0, 10, 20, 30 and 40 cycles of freezing and thawing respectively, are tested by means of the Spilt Hopkinson Pressure Bar technique. The experimental results showed that under dynamic loading the ceramisite concrete was weakened with increasing of the number of freeze-thaw cycles. Changes of dynamic compressive strength and damage evolution affected by freeze-thaw cycling and volume fraction of ceramsite are discussed in the paper.

Abstract: Strain localization in low carbon steel DC04 undergoing uniaxial tension is investigated by Electronic Speckle Pattern Interferometry (ESPI). The necking in the sheet specimens occurs by forming two narrow crossing bands. A model of strain rate distribution is used to extract quantitative information about the localization bands, such as bandwidths, bands orientations and their maximum strain rates. Thus, their evolutions are followed from the diffuse necking up to the rupture. The influence of specimen geometry on localization phenomenon is studied.