TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Thiele, Marc A1 - Unger, Jörg F. T1 - Constitutive modeling of creep-fatigue interaction for normal strength concrete under compression N2 - Conventional approaches to model fatigue failure are based on a characterization of the lifetime as a function of the loading amplitude. The Wöhler diagram in combination with a linear damage accumulation assumption predicts the lifetime for different loading regimes. Using this phenomenological approach, the evolution of damage and inelastic strains and a redistribution of stresses cannot be modeled. The gradual degration of the material is assumed to not alter the stress state. Using the Palmgren–Miner rule for damage accumulation, order effects resulting from the non-linear response are generally neglected. In this work, a constitutive model for concrete using continuum damage mechanics is developed. The model includes rate-dependent effects and realistically reproduces gradual performance degradation of normal strength concrete under compressive static, creep and cyclic loading in a unified framework. The damage evolution is driven by inelastic deformations and captures strain rate effects observed experimentally. Implementation details are discussed. Finally, the model is validated by comparing simulation and experimental data for creep, fatigue and triaxial compression. KW - Fatigue KW - Compression KW - Constitutive modeling KW - Normal strength concrete PY - 2015 DO - https://doi.org/10.1016/j.ijfatigue.2015.03.026 SN - 0142-1123 VL - 78 SP - 81 EP - 94 PB - Elsevier CY - Oxford AN - OPUS4-34158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kindrachuk, Vitaliy A1 - Fedelich, Bernard T1 - Simulation of non-isothermal mechanical tests on a single crystal nickel-basis superalloy N2 - An extension of the constitutive viscoplastic model of Meric and Cailletaud is presented. The new model accounts for coupling of plasticity and viscoplasticity to describe the rate dependence at low and moderate temperatures. The model contains two boundaries: an elastic one and a viscoplastic one. Between the boundaries, the only contribution to yielding is the rate dependent viscoplastic mechanism. Once the viscoplastic boundary is reached, an additional rate independent flow mechanism becomes active. However, the extended model is not able to predict properly both creep and long-term relaxation tests simultaneously. Therefore, a deformation-induced softening is assumed, which is supposed to mainly affect static recovery. The model has been calibrated with the mechanical tests on a single crystal nickel-basis superalloy. The uniaxial tests have been carried out in the temperature interval 600°C – 1100°C in [001], [011] and [111] specimens. The predicted creep, relaxation and non-isothermal cyclic tests exhibit reasonable agreement with the experimental observations. KW - Non-isothermal mechanical tests KW - Superalloys KW - Constitutive modeling PY - 2012 SN - 0232-3869 VL - 32 IS - 2-5 SP - 321 EP - 332 PB - Institut für Mechanik CY - Magdeburg AN - OPUS4-25925 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -