scholarly journals Experimental Study on the Multistage Strength Degradation and the Associated Strain Energy Variation of S25C

2014 ◽  
Vol 891-892 ◽  
pp. 753-758 ◽  
Author(s):  
Zi Hai Shi ◽  
Masaaki Nakano ◽  
Cui Ping Liu
Keyword(s):  
Cyclic Loading ◽  
Strain Energy ◽  
Abrupt Change ◽  
Sudden Change ◽  
Strength Degradation ◽  
Test Results ◽  
Metal Fatigue ◽  
Structural Behaviour ◽  
Engineering Material ◽  
Clear Description

The multistage strength degradation theory, which has recently emerged from studies on the material and structural behaviour of concrete, provides a clear description of the mechanism of fatigue. According to this theory, fatigue is caused by the sporadic sudden change of cracking behaviour in a system under cyclic loading, leading to intermittent strength reduction of the system and its eventual failure. As metal is the main engineering material plagued most by fatigue failure, this newly-established theory needs to be experimentally verified on metal, which is the aim of this study. The obtained test results present strong experimental evidence for the existence of multistage strength degradation processes in metals under cyclic loading, and the strength degradation is clearly triggered by the abrupt change of cracking behaviour. These tests confirm the relevance of the multistage strength degradation theory on metal fatigue, and the engineering implications of the study are discussed.

Application of Energy-Based Damage Model to Simulate Ductile Fracture Under Cyclic Loading and Validation Against Piping System Test Data

2018 ◽  
Author(s):  
Gyo-Geun Youn ◽  
Hyun-Suk Nam ◽  
Hune-Tae Kim ◽  
Jong-Min Lee ◽  
Yun-Jae Kim
Keyword(s):  
Cyclic Loading ◽  
Ductile Fracture ◽  
Strain Energy ◽  
Loading Condition ◽  
Fracture Strain ◽  
Damage Model ◽  
Test Results ◽  
Cyclic Loading Condition ◽  
Low Cyclic Loading ◽  
Axial Fracture

In this paper, a method to predict ductile fracture under low cyclic loading condition is proposed. Then it is compared with test results of surface cracked pipes which is conducted by Battelle Institute. A&F nonlinear kinematic hardening model is adopted to describe material behavior under cyclic loading condition and energy-based damage model is applied to simulate ductile crack growth. The energy-based damaged model is depending on multi-axial fracture strain energy. To apply this model, two parameters should be determined from tensile and C(T) test results under monotonic loading condition. One is multi-axial fracture strain energy Wf and the other is critical damage value ωc. From the determined damaged model, it is enable to simulate surface cracked pipe tests under low cyclic loading condition.

Experimental Study on Steel Frames Infilled with Sandwich Composite Panels

2011 ◽  
Vol 243-249 ◽  
pp. 499-505
Author(s):  
Can Xing Qiu ◽  
He Tao Hou ◽  
Wei Long Liu ◽  
Ming Lei Wu
Keyword(s):  
Seismic Design ◽  
Steel Frames ◽  
Strength Degradation ◽  
Hysteretic Behavior ◽  
Sandwich Composite ◽  
Viscous Damping ◽  
Test Results ◽  
Ductility Index ◽  
Damage Process ◽  
Seismic Behaviors

A model of full scale one-bay, one storey was tested under low cyclic loading in order to study the hysteretic behavior of steel frames with sandwich composite (SC) panels. According to the failure pattern and damage process of test specimen, seismic behaviors were evaluated. Hysterics loops, skeleton curves, curves of strength degradation, and curves of stiffness degradation, ductility index and viscous damping coefficient were analyzed. Test results show that the failures of panels mainly occurred around the embedded parts, but compared with traditional panels and walls, SC panels exhibit a better integration. The connection between panel and steel frame is vital to the mutual work of the two parts. Finally, seismic design recommendations based on the analysis of ductility index and energy dissipation of the structures are presented.

The Properties of Welded Joints Made by 6082-T6 Aluminium Alloy and their Behaviour under Cyclic Loading Conditions

2015 ◽  
Vol 812 ◽  
pp. 375-380 ◽  
Author(s):  
D. Pósalaky ◽  
János Lukács
Keyword(s):  
Cyclic Loading ◽  
Automotive Industry ◽  
Welded Joints ◽  
Structural Engineering ◽  
Physical Simulation ◽  
Base Material ◽  
Point Of View ◽  
Test Results ◽  
Structural Elements ◽  
Effective Use

The magnitude of different aluminium alloys, especially the ones with higher strength, are increasing in the structural engineering, not just the usual applications (like the aerospace industry) but more likely in the automotive industry. There are more assumptions of the effective use of aluminium; we should highlight two important factors, the technological and the applicability criterions. The technological criterion is the joining of structural elements, frequently with welding thus the technological criterion ultimately is the weldability. The assumption of applicability comes from the loading capability of these structures, which is typically cyclic loading so the key issue from the point of view of applicability is the resistance to fatigue. This article represents physical simulation and fatigue test results both on the base material and on the welded joints.

scholarly journals Conjectural Bifurcation Analysis of an Aircraft Engine Blade Undergoing 3D Unilateral Contact Constraints

2014 ◽  
Author(s):  
Alain Batailly ◽  
Mathias Legrand
Keyword(s):  
Spline Interpolation ◽  
Sudden Change ◽  
Aircraft Engine ◽  
Rotational Frequency ◽  
Compressor Blade ◽  
Structural Behaviour ◽  
Mode Decomposition ◽  
Abradable Coating ◽  
Set Up ◽  
Pressure Compressor

Prediction of rotor/stator interaction phenomena between a blade-tip and the surrounding abradable coating deposited on the casing has seen recent promising numerical developments that revealed consistency with several experimental set-up. In particular, the location of critical rotational frequencies, damaged blade areas as well as the wear pattern along the casing circumference were accurately predicted for an interaction scenario involving a low-pressure compressor blade and the surrounding abradable coating deposited on a perfectly rigid casing. The structural behaviour of the blade in the vicinity of a critical rotational frequency however remains unclear as brutal amplitude variations observed experimentally could not be numerically captured without assuming contact loss or an improbable drastic and sudden change of the abradable coating mechanical properties during the interaction. In this paper, attention is paid to the structural behaviour of a high-pressure compressor blade at the neighbourhood of a critical rotational frequency. The interaction scenarios for two close rotational frequencies: Ωc and Ωc* are analyzed using empirical mode decomposition based on an adjusted B-spline interpolation of the time responses. The obtained results are compared to the interaction scenario dictated by the abradable coating removal history and the location of contact areas. The unstable nature of the blade vibratory response when the rotational frequency exceeds a critical rotational frequency is underlined and a plausible scenario arises for explaining a sudden and significant decrease of the blade amplitude of vibration without contact separation.

scholarly journals Undrained Pore Pressure Development on Cohesive Soil in Triaxial Cyclic Loading

2019 ◽  
Vol 9 (18) ◽  
pp. 3821 ◽  
Author(s):  
Andrzej Głuchowski ◽  
Emil Soból ◽  
Alojzy Szymański ◽  
Wojciech Sas
Keyword(s):  
Stress State ◽  
Cyclic Loading ◽  
Pore Pressure ◽  
Cohesive Soil ◽  
Soil Samples ◽  
Test Results ◽  
Soil Behavior ◽  
Pressure Development ◽  
Undrained Conditions ◽  
Excess Pore

Cohesive soils subjected to cyclic loading in undrained conditions respond with pore pressure generation and plastic strain accumulation. The article focus on the pore pressure development of soils tested in isotropic and anisotropic consolidation conditions. Due to the consolidation differences, soil response to cyclic loading is also different. Analysis of the cyclic triaxial test results in terms of pore pressure development produces some indication of the relevant mechanisms at the particulate level. Test results show that the greater susceptibility to accumulate the plastic strain of cohesive soil during cyclic loading is connected with the pore pressure generation pattern. The value of excess pore pressure required to soil sample failure differs as a consequence of different consolidation pressure and anisotropic stress state. Effective stresses and pore pressures are the main factors that govern the soil behavior in undrained conditions. Therefore, the pore pressure generated in the first few cycles plays a key role in the accumulation of plastic strains and constitutes the major amount of excess pore water pressure. Soil samples consolidated in the anisotropic and isotropic stress state behave differently responding differently to cyclic loading. This difference may impact on test results analysis and hence may change the view on soil behavior. The results of tests on isotropically and anisotropically consolidated soil samples are discussed in this paper in order to point out the main features of the cohesive soil behavior.

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