Durability of Concrete Under the Combined Action of Carbonization and Fatigue Loading of Vehicles

2019 ◽  
Vol 11 (12) ◽  
pp. 1781-1787
Author(s):  
Yuan-Yao Miao ◽  
Di-Tao Niu ◽  
Ning Cheng
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Atmospheric Environment ◽  
Climate Simulation ◽  
Concrete Durability ◽  
Loading Level ◽  
Damage Degree ◽  
Vehicle Loading ◽  
Combined Action

Natural factors such as environments gradually cause the aging of structural materials of concrete bridges and mechanical properties of the components are constantly degraded. When highway bridge structures are under the combined with vehicle loading and environmental diversities, the degradation of structural performance is further aggravated. In this study, according to the deterioration trend of concrete durability in atmospheric environment, durability tests for concrete under the combined action of fatigue loading of vehicles and carbonization were performed by artificial climate simulation. A bending fatigue test for concrete under vehicle loading was carried out, and the trend of fatigue life change with vehicle loading level and the trend of fatigue strain development were obtained. The results show that the fatigue life increases with the decrease in fatigue loading level of vehicles, and the logarithmic value of fatigue life Nf is linear with the fatigue stress level S. Fast carbonization tests for concrete were performed with respect to the fatigue damage degree D of 0, 0.2, 0.4, 0.6, and 0.8. It was found that the carbonization trend of fatigue damaged concrete under vehicle loading follows the Fick first law. The carbonization depth increases with the increase in carbonization time, relatively fast at the initial stage and then slowly at the later stage. When the fatigue damage degree D is less than 0.4, the effects of fatigue damage on carbonization is relatively small. When D is more than 0.4, the effect of fatigue damage on carbonization is relatively significant. The extension of interior micro-cracks and micropores caused by fatigue damage is a significant factor affecting the carbonization performance of fatigue damaged concrete. The change trend of carbonization depth of damaged concrete with time was fitted and analyzed. An influencing factor of fatigue damage was introduced, and a durability prediction model for concrete under the combined action of carbonization and fatigue loading of vehicles was established.

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

A Theory for Mathematical Framework of Fatigue Damage on S-N Plane

2014 ◽  
Vol 627 ◽  
pp. 117-120 ◽  
Author(s):  
Hoda Eskandari ◽  
Ho Sung Kim
Keyword(s):  
Fatigue Life ◽  
Boundary Conditions ◽  
Fatigue Damage ◽  
Fatigue Loading ◽  
Mathematical Framework ◽  
Accumulated Damage ◽  
Damage Quantification ◽  
Damage Equation

A theory for mathematical framework is developed with axioms for fatigue damage, quantification and relativity concept, boundary conditions, and compatibility, allowing us to evaluate the validity of candidate damage equations/quantities on S-N plane for prediction of fatigue life. Manifestation points for accumulated damage were defined for boundary conditions by differentiating between damage accumulated before failure, and failure caused by damage at quantised fatigue loading cycles. A selected damage equation leading to a theoretical S-N curve was validated as an example.

Load Spectrum Compiling and Practical Application of Output Flange for Wheel Loader Gearbox

2011 ◽  
Vol 346 ◽  
pp. 483-489
Author(s):  
Ying Shuang Zhang ◽  
Guo Qiang Wang ◽  
Ji Xin Wang
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Prediction Method ◽  
Fatigue Loading ◽  
Load Spectrum ◽  
Element Analysis ◽  
Wheel Loader ◽  
Program Load Spectrum ◽  
Program Load

To realize the structural light weighting design of the transmission components of engineering vehicles on the basis of life in control, this paper took wheel loader as an example, collected the time-domain load signals of the transmission system in typical working conditions, provided processing steps for load spectrum synthesis by a certain percentage, and generated the program load spectrum which consisted of various amplitudes and means. The load spectrum can be used for fatigue loading at the output flange of gearbox. Then, the finite element model of the flange was established, and the stress analysis was carried out in the stress concentration location such as fillet. The prediction method of fatigue life on the base of program load spectrum was given. After the fatigue life prediction based on the compiled load spectrum and the theory of cumulative fatigue damage, the fatigue life of outside fillet of the flange, where is of maximum stress, is obtained. It was possible to obtain adequately fatigue prediction results in engineering vehicle design, using load spectrum, finite element analysis, and a stress-life approach to fatigue damage calculations.

Experimental Damage Mechanics of Microelectronic Solder Joints Under Fatigue Loading

2002 ◽  
Author(s):  
Cemal Basaran ◽  
Hong Tang ◽  
Shihua Nie
Keyword(s):  
Elastic Modulus ◽  
Fatigue Life ◽  
Thermal Cycling ◽  
Fatigue Damage ◽  
Solder Joints ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Load Drop ◽  
Material Degradation ◽  
Elastic Modulus Degradation

Fatigue damage is a progressive process of material degradation. The objective of this study is to experimentally qualify the damage mechanism in solder joints in electronic packaging under thermal fatigue loading. Another objective of this paper is to show that damage mechanism under thermal cycling and mechanical cycling is very different. Elastic modulus degradation under thermal cycling, which is considered as a physically detectable quantity of material degradation, was measured by Nano-indenter. It was compared with tendency of inelastic strain accumulation of solder joints in Ball Grid Array (BGA) package under thermal cycling, which was measured by Moire´ interferometry. Fatigue damage evolution in solder joints with traditional load-drop criterion was also investigated by shear-strain hysteresis loops from strain-controlled cyclic shear testing of thin layer solder joints. Load-drop behavior was compared with elastic modulus degradation of solder joints under thermal cycling. Following conventional Coffin-Manson approach, S-N curve was obtained from isothermal fatigue testing with load-drop criterion. Coffin-Manson curves obtained from strain controlled mechanical tests were used to predict fatigue life of solder joints. In this paper it is shown that this approach underestimates the fatigue life by an order of magnitude. Results obtained in this project indicate that thermal fatigue and isothermal mechanical fatigue are completely different damage mechanism for microstructurally evolving materials.

scholarly journals Thermo-mechanical fatigue damage behavior for Ni-based superalloy under multiaxial loading

2018 ◽  
Vol 165 ◽  
pp. 19002
Author(s):  
Dao-Hang Li ◽  
De-Guang Shang
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Tensile Stress ◽  
Fatigue Damage ◽  
Mechanical Strain ◽  
Creep Damage ◽  
Fatigue Loading ◽  
Shear Stresses ◽  
Damage Behavior ◽  
Von Mises

The fatigue damage behavior was experimentally investigated in different axial-torsional thermo-mechanical loading conditions for Ni-based superalloy GH4169. The strain controlled tests were carried out with the same von Mises equivalent mechanical strain amplitude of 0.8% in the temperature range from 360°C to 650°C. The results show that the fatigue life is drastically reduced when the axial mechanical strain and the temperature are in-phase, which can be due to that the creep damage is induced by the tensile stress at high temperature. Moreover, the fatigue life is further decreased when the axial mechanical strain and the shear strain are out-of-phase, which can be attributed to that the non-proportional hardening can increase the creep and the oxidation damages. Furthermore, the tensile stress is crucial to the nucleation of creep cavities at high temperature compared with the shear stress. The tensile and shear stresses all can increase the creep damage under fatigue loading at high temperature. In addition, the oxidation damage can be induced during cyclic loading at high temperature, and it can be increased by the tensile mean stress caused in non-isothermal loading.

scholarly journals NUMERICALLY MODELING FATIGUE LIFE OF STRUCTURAL ELEMENTS UNDER THERMAL CYCLIC LOADING

2020 ◽  
Vol 82 (2) ◽  
pp. 168-188
Author(s):  
I.A. Volkov ◽  
L.A. Igumnov ◽  
D.N. Shishulin ◽  
V.A. Eremeev
Keyword(s):  
Plastic Deformation ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Strength Criterion ◽  
Cyclic Fatigue ◽  
Defining Relations ◽  
Damage Degree ◽  
Fatigue Damage Accumulation ◽  
Main Effects

The paper considers processes of fatigue life of materials and structures in the exploitation conditions characterized by multiparametric nonstationary thermal-mechanical effects In the framework of mechanics of damaged media, a mathematical model is developed that describes processes of thermal-plastic deformation and fatigue damage accumulation in materials with degradation according to low- and high-cycle fatigue mechanisms (accounting for their interaction). The model consists of three interconnected parts: relations determining cyclic thermal-plastic behavior of a material, accounting for its dependence on the failure process; equations describing kinetics of fatigue damage accumulation; a strength criterion of the damaged material. The version of the defining relations of thermal plasticity is based on the notion of the yield surface and the principle of orthogonality of the plastic strain rate vector to the yield surface at the loading point and reflects the main effects of the process of cyclic plastic deformation of the material for arbitrarily complex trajectories of combined thermal-mechanical loading. The version of kinetic equations of fatigue damage accumulation is based on introducing a scalar parameter of damage degree and on energy-based principles, and takes into account the main effects of the nucleation, growth and merging of microdefects under arbitrarily complex loading regimes. A generalized form of an evolutionary equation of fatigue damage accumulation in low-cycle and high-cycle fatigue regions is introduced. The condition when the damage degree reaches its critical value is taken as the strength criterion of the damaged material. To assess the reliability and the scope of applicability of the developed defining relations of mechanics of damaged media, processes of thermal-plastic deformation and fatigue damage accumulation have been numerically analyzed, and the numerical results obtained have been compared with the data of full-scale experiments for a particular applied problem. The effect of the dropping frequency of a distillate on thermal cyclic fatigue life of the material of a heated surface of a tube has been numerically analyzed. The computational results for the fatigue damage accumulation processes under thermal pulsed loading are compared with experimental data. It is shown that the developed model describes both qualitatively and, accurately enough for engineering purposes, quantitatively the experimental data and can be effectively used for evaluating thermal-cyclic fatigue life of structures working in the conditions of multiaxial non-proportional regimes of combined thermal-mechanical loading.

scholarly journals Mode II Behavior of High-Strength Concrete under Monotonic, Cyclic and Fatigue Loading

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7675
Author(s):  
Henrik Becks ◽  
Martin Classen
Keyword(s):  
Fatigue Life ◽  
Compressive Stress ◽  
Fatigue Damage ◽  
High Strength Concrete ◽  
High Strength ◽  
Fatigue Loading ◽  
Mode Ii ◽  
Shear Tests ◽  
Strength Concrete ◽  
Mode Ii Loading

An economically efficient yet safe design of concrete structures under high-cycle fatigue loading is a rather complex task. One of the main reasons is the insufficient understanding of the fatigue damage phenomenology of concrete. A promising hypothesis states that the evolution of fatigue damage in concrete at subcritical load levels is governed by a cumulative measure of shear sliding. To evaluate this hypothesis, an experimental program was developed which systematically investigates the fatigue behavior of high-strength concrete under mode II loading using newly adapted punch through shear tests (PTST). This paper presents the results of monotonic, cyclic, and fatigue shear tests and discusses the effect of shear-compression-interaction and load level with regard to displacement and damage evolution, fracture behavior, and fatigue life. Both, monotonic shear strength and fatigue life under mode II loading strongly depend on the concurrent confinement (compressive) stress in the ligament. However, it appears that the fatigue life is more sensitive to a variation of shear stress range than to a variation of compressive stress in the ligament.

Welded Joint Fatigue Cumulative Damage MMM Characteristic

2012 ◽  
Vol 566 ◽  
pp. 61-64
Author(s):  
Hai Yan Xing ◽  
Wen Guang Yang ◽  
Yi Nan E
Keyword(s):  
Fatigue Damage ◽  
Welded Joint ◽  
Fatigue Loading ◽  
Cyclic Fatigue ◽  
Mechanical Effect ◽  
Cumulative Damage ◽  
Welding Residual Stress ◽  
Magnetic Memory ◽  
Average Value ◽  
Damage Degree

Metal magnetic memory (MMM) technology, based on magnetic-mechanical effect, is a new nondestructive testing. In order to study MMM signal characteristics of welded joint fatigue cumulative damage, Steel 20 welded plate specimens were tested under multi-cyclic fatigue loading. The average value of fatigue loading is 35kN and the stress ratio is 1/6. The MMM behavior of the welded joint fatigue cumulative damage is given. It has been found that non-uniform welding residual stress influences MMM signal distribution at the initial stage of the experiment. With the increasing of fatigue cycles, welded joint fatigue damage is cumulated and the stress is redistributed again. MMM signal begins to be stable regular and shows a fluctuation-arising trend along with the increase of damage degree. By establishing the relationship between the damage degree and the MMM characteristic signals, the welded joint cumulative fatigue damage can be evaluated by MMM method.

scholarly journals New Nonlinear Cumulative Fatigue Damage Model Based on Ecological Quality Dissipation of Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hongsong Li ◽  
Yongbao Liu ◽  
Xing He ◽  
Wangtian Yin
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Loading ◽  
Ecological Quality ◽  
Aircraft Structures ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Cumulative Fatigue Damage

The failure of many aircraft structures and materials is caused by the accumulation of fatigue damage under variable-amplitude cyclic loading wherein the damage evolution of materials is complicated. Therefore, to study the cumulative fatigue damage of materials under variable-amplitude cyclic loading, a new nonlinear fatigue damage accumulation model is proposed based on the ecological quality dissipation of materials by considering the effects of load interaction and sequence. The proposed new model is validated by the test data obtained for three kinds of material under multilevel fatigue loading. Compared with the Miner model and Kwofie model, the proposed model can more effectively analyse the accumulative damage and predict fatigue life of different materials under variable-amplitude cyclic loading than others. The study provides a basis for predicting fatigue life accurately and determining reasonable maintenance periods of aircraft structures.

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