scholarly journals Numerical analysis of mechanical damage on concrete under high temperatures

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Lahis Souza de Assis ◽  
Matheus Fernandes Dal Sasso ◽  
Michèle Cristina Resende Farage ◽  
Flávia de Souza Bastos ◽  
Anne-Lise Beaucour
Keyword(s):  
High Temperatures ◽  
Thermal Loading ◽  
Damage Model ◽  
Mechanical Damage ◽  
Structural Complexity ◽  
Thermomechanical Behavior ◽  
Computational Tools ◽  
User Subroutine ◽  
Loading Effects ◽  
Abaqus Software

Abstract Concrete is a widespread material all over the world. Due to this material’s heterogeneity and structural complexity, predicting the behavior of concrete structures under extreme environmental conditions is a very challenging task. High temperatures lead to microstructural changes which affect the macrostructural performance. In this context, computational tools that allow the simulation of structures may assist the analysis, by reproducing varied situations of thermal and mechanical loading and boundary conditions. In order to contribute to this scenario, this study proposes a numerical methodology to simulate the thermomechanical behavior of concrete under temperature gradients, through inverse analyses and a user subroutine implemented in Abaqus software. Thermal loading effects were considered as loading data for a damage model. Experimental data available in the literature was adopted for adjustment and validation purposes. The preliminary results presented herein encourage further improvements so as to allow realistic simulations of such an important aspect of concrete’s behavior.

scholarly journals Coupled Thermal-Mechanical Progressive Damage Model with Strain and Heating Rate Effects for Lightning Strike Damage Assessment

2019 ◽  
Vol 26 (5-6) ◽  
pp. 1437-1459 ◽  
Author(s):  
S. L. J. Millen ◽  
A. Murphy ◽  
G. Catalanotti ◽  
G. Abdelal
Keyword(s):  
Heating Rate ◽  
Thermal Loading ◽  
Damage Model ◽  
Applied Pressure ◽  
Mechanical Damage ◽  
Failure Criteria ◽  
Lightning Strike ◽  
Progressive Damage ◽  
Rate Effects ◽  
Progressive Damage Model

AbstractThis paper proposes a progressive damage model incorporating strain and heating rate effects for the prediction of composite specimen damage resulting from simulated lightning strike test conditions. A mature and robust customised failure model has been developed. The method used a scaling factor approach and non-linear degradation models from published works to modify the material moduli, strength and stiffness properties to reflect the effects of combined strain and thermal loading. Hashin/Puck failure criteria was used prior to progressive damage modelling of the material. Each component of the method was benchmarked against appropriate literature. A three stage modelling framework was demonstrated where an initial plasma model predicts specimen surface loads (electrical, thermal, pressure); a coupled thermal-electric model predicts specimen temperature resulting from the electrical load; and a third, dynamic, coupled temperature-displacement, explicit model predicts the material state due to the thermal load, the resulting thermal-expansion and the lightning plasma applied pressure loading. Unprotected specimen damage results were presented for two SAE lightning test Waveforms (B & A); with the results illustrating how thermal and mechanical damage behaviour varied with waveform duration and peak current.

scholarly journals Thermomechanical fatigue behaviour of ferritic stainless steel grades for high temperatures applications

2018 ◽  
Vol 165 ◽  
pp. 16003
Author(s):  
Cloé Prudhomme ◽  
Pierre-Olivier Santacreu ◽  
Isabelle Evenepoel ◽  
Benoit Proult
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
High Temperatures ◽  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Thermomechanical Fatigue ◽  
Compression Tests ◽  
Wide Range ◽  
Steel Grades

Nowadays high temperatures resistant materials are needed to resist to high temperature applications (up to 1000°C), such as automotive exhaust gas manifolds. Some developed stainless steel grades, including ferritic grades or austenitic refractory grades, can be used in this temperature range and both in continuous or cyclic thermal conditions. In order to predict the thermomechanical fatigue damage of stainless steel parts submitted to cyclic thermal loading and constrained bonding conditions, the elastoviscoplastic model by Chaboche is determined for a wide range of temperatures, of strain amplitudes and strain rate levels thanks to isothermal traction-compression tests. The validation procedure is performed afterward by comparison with stabilized behavior under non isothermal conditions on a dedicated thermal fatigue test performed on V-shape specimens. Results of simulation show very good fitting with the experimental curves which would lead to a more accurate fatigue life prediction. A damage model was derived from Taira’s thermal low-cycle fatigue model to include dwell-time period at high temperature and creep-oxidation effect. In this paper the example of K44X, a dedicated grade for high temperatures applications, is presented.

Numerical and Experimental Investigations on SGMF of GH3044 Superalloy Tube

2014 ◽  
Vol 915-916 ◽  
pp. 668-672 ◽  
Author(s):  
Li Jun Wu ◽  
Chang Cai Zhao ◽  
Guo Jiang Dong
Keyword(s):  
Experimental System ◽  
Elongation Rate ◽  
High Yield ◽  
Experimental Investigations ◽  
High Yield Strength ◽  
New Approach ◽  
Nickel Based Superalloy ◽  
User Subroutine ◽  
Granules Medium ◽  
Abaqus Software

According to the GH3044 nickel-based superalloy with high yield strength, a new approach for superalloy tube named Tube Solid Granules Medium Forming (SGMF) was present, and tube SGMF process principle and the mechanical model of solid granules were designed. The superalloy tube SGMF process was investigated numerically by using User subroutine of Abaqus software, the deforming simulations of two groups of tube products were performed separately, and the elongation rate and thickness distributions of the products were analyzed. An experimental system was designed and developed for tube SGMF, typical GH3044 superalloy tubes were deformed, good correlation was observed between the simulation results and experimental data.

A Rational Methodology for Determination of Service Life for a Delayed Coker Drum

2015 ◽  
Author(s):  
John J. Aumuller ◽  
Jie Chen ◽  
Vincent A. Carucci
Keyword(s):  
Service Life ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Mechanical Damage ◽  
Damage Mechanism ◽  
Modern Trend ◽  
Cold Spot ◽  
Chromium Alloy ◽  
Cycle Fatigue ◽  
Service Environment

Delayed unit coker drums operate in a severe service environment that precludes long term reliability due to excessive shell bulging and cracking of shell joint and shell to skirt welds. Thermal fatigue is recognized as the leading damage mechanism and past work has provided an idealized description of the thermo-mechanical mechanism via local hot and cold spot formation to quantify a lower bound life estimate for shell weld failure. The present work extends this idealized thermo-mechanical damage model by evaluating actual field data to determine a potential upper bound life estimate. This assessment also provides insight into practical techniques for equipment operators to identify design and operational opportunities to extend the service life of coke drums for their specific service environments. A modern trend of specifying higher chromium and molybdenum alloy content for drum shell material in order to improve low cycle fatigue strength is seen to be problematic; rather, the use of lower alloy materials that are generally described as fatigue tough materials are better suited for the high strain-low cycle fatigue service environment of coke drums. Materials such as SA 204 C (C – ½ Mo) and SA 302 B (C – Mn – ½ Mo) or SA 302 C (C – Mn – ½ Mo – ½ Ni) are shown to be better candidates for construction in lieu of low chromium alloy steel materials such as SA 387 grades P11 (1¼ Cr – ½ Mo), P12 (1 Cr – ½ Mo), P22 (2¼ Cr – 1 Mo) and P21 (3 Cr – 1 Mo).

The Effects of Cooling Holes on the Creep Life in a Modeling Specimen of Single Crystal Air-Cooled Turbine Blade

2011 ◽  
Vol 284-286 ◽  
pp. 1678-1683 ◽  
Author(s):  
Da Shun Liu ◽  
Bai Zhi Wang ◽  
Zhi Xun Wen ◽  
Zhu Feng Yue
Keyword(s):  
Single Crystal ◽  
Turbine Blade ◽  
Damage Model ◽  
Creep Damage ◽  
Creep Life ◽  
Damage Development ◽  
User Subroutine ◽  
Initial Rupture ◽  
Creep Deformations ◽  
Sem Analyses

This paper presents the study of the influences of cooling holes on the creep life behavior in the modeling specimen of single crystal cooling turbine blade at high temperature. Thin-walled cylindrical specimens with holes are tested to model the air-cooled turbine blade. Specimens without holes are also studied to make comparisons. Experimental results show that at 900°C, the creep lives of specimens with holes are longer than those of specimens without holes. Scanning Electron Microscopy (SEM) analyses reveal that creep deformations occur firstly around the cooling holes and finally rupture at the region with low stress and strain. Finite element analyses are used to study the creep damage development by a K-R damage model which has been implemented into the Abaqus user subroutine (UMAT). Simulation results show that stress concentration and redistribution occur around the cooling holes during the creep development. It is also shown that the maximum strain and stress are around the cooling holes which are the initial rupture region in the experiments.

Investigations of size effects in tensile tests based on a nonlocal micro-mechanical damage model

2003 ◽  
Vol 26 ◽  
pp. 230-243 ◽  
Author(s):  
Huang Yuan ◽  
Jian Chen ◽  
Klaus Krompholz ◽  
Folker H. Wittmann
Keyword(s):  
Size Effects ◽  
Damage Model ◽  
Mechanical Damage ◽  
Tensile Tests
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