scholarly journals Low-Cycle Fatigue Crack Initiation Simulation and Life Prediction of Powder Superalloy Considering Inclusion-Matrix Interface Debonding

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4018
Author(s):  
Shuming Zhang ◽  
Yuanming Xu ◽  
Hao Fu ◽  
Yaowei Wen ◽  
Yibing Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Fatigue Loading ◽  
Interface Debonding ◽  
Damage Evolution Equation ◽  
Finite Element Software

From the perspective of damage mechanics, the damage parameters were introduced as the characterizing quantity of the decrease in the mechanical properties of powder superalloy material FGH96 under fatigue loading. By deriving a damage evolution equation, a fatigue life prediction model of powder superalloy containing inclusions was constructed based on damage mechanics. The specimens containing elliptical subsurface inclusions and semielliptical surface inclusions were considered. The CONTA172 and TARGE169 elements of finite element software (ANSYS) were used to simulate the interfacial debonding between the inclusions and matrix, and the interface crack initiation life was calculated. Through finite element modeling, the stress field evolution during the interface debonding was traced by simulation. Finally, the effect of the position and shape size of inclusions on interface debonding was explored.

CDM Approach Applied to Crack Initiation and Propagation under Variable Amplitude

2016 ◽  
Vol 829 ◽  
pp. 55-60
Author(s):  
Jin Yang Chu ◽  
Jian Xing Mao
Keyword(s):  
Crack Initiation ◽  
Damage Accumulation ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Continuum Damage Mechanics ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Crack Initiation Life ◽  
Initiation Stage

In this paper, the low cycle fatigue crack initiation life was regarded as a process of damage accumulation and a damage accumulation model was established based on the Continuum Damage Mechanics. By the model, we analyzed how the variable amplitude applied at the crack initiation stage influenced the low cycle fatigue life of high temperature materials. With the parameters of GQGH4169 alloy at room temperature, we determined the specific values of damage parameters by finite element method and numerical analysis method. Then, the crack initiation life predictions were carried out. The results show that using this approach can not only predict the crack initiation life of CT specimen accurately, but also reflect a definite influence of variable amplitude on the crack propagation life combining with the Paris Law, and the test costs reduced consequently.

Damage Mechanics-Finite Element Method for Vibrational Fatigue Life Prediction of Engineering Structures with Damping

2014 ◽  
Vol 472 ◽  
pp. 17-21 ◽  
Author(s):  
Lin Lin Sun ◽  
Wei Ping Hu ◽  
Miao Zhang ◽  
Qing Chun Meng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Fatigue Crack Initiation ◽  
Engineering Structures ◽  
Engineering Structure ◽  
Crack Initiation Life ◽  
Element Method

This paper provides a new method which is damage mechanics to predict the fatigue life of engineering structure with damping under resonant loading. The material parameters are obtained by the results of the fatigue test of standard specimens. And based on the further development of APDL language, damage mechanics-finite element method for vibration life prediction under resonant loading is used in ANSYS. Finally, the vibrational fatigue crack initiation life of an aluminum alloy beam with damping carrying load of various frequencies is calculated. Whats more, this research provides a feasible way to predict the fatigue live of an engineering structure by means of damage mechanics.

Crack Initiation Life Model of Stiffened Plates Based on Damage Mechanics

2014 ◽  
Vol 904 ◽  
pp. 508-512
Author(s):  
Hong Wang ◽  
Ping Yang ◽  
Jun Lin Deng ◽  
Qin Dong
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Plastic Strain ◽  
Fatigue Damage ◽  
Damage Evolution ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Stiffened Plate ◽  
Crack Initiation Life

Based on the continuum damage mechanics theory, according to the development of the fatigue damage evolution equation, and combining the interaction coefficient of stiffener and plate, with plastic strain as the control quantity of damage evolution, the stiffened plate low cycle fatigue damage mechanics model is established, and the calculation method of the fatigue crack initiation life is obtained. This method for the initiation life of fatigue crack is divided into the life before the damage and the life of the damage evolution. The model results are compared with those of the finite element results. Conclusions show that the model can reflect the regularity of axial plastic strain evolution of stiffened plate, and can be directly used for fatigue loads analysis under the mechanism of initiation life.

scholarly journals An Experimental Study on Low-Cycle Fatigue Crack Initiation Life Prediction of Powder Superalloy FGH96 Based on the Manson-Coffin and Damage Mechanics Methods

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 489
Author(s):  
Yuanming Xu ◽  
Hao Chen ◽  
Shuming Zhang ◽  
Tianpeng He ◽  
Xuerong Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Life Cycles ◽  
Cycle Fatigue ◽  
Element Analysis

The applicability of both prediction methods for low-cycle fatigue life of powder superalloy based on the Manson-Coffin equation and damage mechanics were addressed. Both fatigue life prediction models were evaluated by low-cycle fatigue experimental data of powder superalloy FGH96 with non-destructive standard parts and those with inclusions. Due to the characteristics of high strength and low plasticity of powder superalloy FGH96, errors in calculating the plastic strain amplitude deviate severely the prediction outcomes when using Manson-Coffin method. Meanwhile, by introducing the damage variable which characterizes the material damage, the damage evolution equation can be built by fitting the experimental data of standard parts and also applied to powder superalloy specimens containing inclusion. It is indispensable to accurately calculate the damage characterization parameter through finite element analysis in local stress concentration around the inclusion. The applicability of the prediction model was verified by the test life cycles of experimental specimens with different types and sizes of inclusions subsequently. Testing and simulation work showed much better prediction accuracies globally for the damage mechanics approach.

Fatigue life prediction of engaging spur gears using power density

2018 ◽  
Vol 232 (23) ◽  
pp. 4332-4341 ◽  
Author(s):  
Yulong Lin ◽  
Shourong Liu ◽  
Xueyan Zhao ◽  
Enrong Mao ◽  
Chao Cao ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Power Density ◽  
Life Prediction ◽  
Fatigue Crack Initiation ◽  
Fatigue Life Prediction ◽  
Spur Gears ◽  
Pinion Gear

The high cycle fatigue performance of an input spur gear pair found in the gearbox of a 4LZ-2 combined harvester with a maximum walking power of 15 kW is investigated. A three-dimensional finite element model of the two engaging spur gears is developed to estimate the fatigue life of the pinion gear subject to bending induced crack initiation and propagation. The critical point of the pinion gear is obtained along with the associated bending stress-time history. The novel concept of power density is applied to the finite element result to correlate fatigue crack initiation and subsequent crack growth with the number of loading cycles undergone. After the location of crack initiation is identified, fatigue crack propagation is modelled using linear elastic fracture mechanics. The estimated fatigue life of the pinion gear is 886 h. A fatigue test rig is employed to physically demonstrate the feasibility of the power density concept for predicting gear fatigue life. It is shown that the power density concept is preferred over the Miner rule for higher accuracy in fatigue life prediction.

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