scholarly journals An Improved Nonlinear Cumulative Damage Model Considering the Influence of Load Sequence and Its Experimental Verification

2021 ◽  
Vol 11 (15) ◽  
pp. 6944
Author(s):  
Wei Wang ◽  
Jianmin Li ◽  
Jun Pan ◽  
Huanguo Chen ◽  
Wenhua Chen
Keyword(s):  
Damage Model ◽  
Recursive Formula ◽  
Fatigue Tests ◽  
Cumulative Damage ◽  
Change Characteristics ◽  
Damage Process ◽  
Dissipation Model ◽  
Damage Accumulation Model ◽  
Cumulative Damage Model ◽  
Load Sequence

According to the change characteristics in the toughness of the metal material during the fatigue damage process, the fatigue tests were carried out with the standard 18CrNiMo7-6 material. Scanning the fracture with an electron microscope explains the lack of linear cumulative damage in the mechanism. According to the obtained results, a nonlinear damage accumulation model which considered the loading sequence state under the toughness dissipation model was established. The recursive formula was devised under two-level. The fatigue test data verification of three metal materials showed that using this model to predict fatigue life is satisfactory and suitable for engineering applications.

scholarly journals Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199530
Author(s):  
Bixiong Huang ◽  
Shuci Wang ◽  
Shuanglong Geng ◽  
Xintian Liu
Keyword(s):  
Fatigue Life ◽  
Theoretical Basis ◽  
Life Prediction ◽  
Damage Model ◽  
Cumulative Damage ◽  
Load Spectrum ◽  
Random Load ◽  
Mechanical Parts ◽  
Proposed Model ◽  
Load Sequence

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

scholarly journals Study on the Mechanical Cumulative Damage Model of Slope Fault Fracture Zone under the Cumulative Effect of Blasting Vibration

2020 ◽  
Author(s):  
Tingyao Wu ◽  
Zhou Chuanbo ◽  
Jiang Nan ◽  
Xia Yuqing ◽  
Bin Zhu
Keyword(s):  
Shear Strength ◽  
Fracture Zone ◽  
Damage Model ◽  
Cumulative Damage ◽  
Shaking Table ◽  
Blasting Vibration ◽  
Fault Fracture Zone ◽  
Table Model ◽  
Damage Theory ◽  
Cumulative Damage Model

As for the slope with fault fracture zone, the fault fracture zone is the main sliding surface, whose shear strength parameter is the main calculation parameter of landslide occurrence. In this paper, shaking table model tests and damage theory were used to study the change of shear strength and mechanical cumulative damage model of fault fracture zone under the blasting vibration cyclic load. At first, the slope of Daye Iron Mine is selected as a case to study the shear strength weakening law of fault fracture zone by the similarity theory and the principle of the orthogonal test, in which the influence of the characteristics of vibration loading on the shear strength parameters of fault fracture zone with different thicknesses was studied. Secondly, by the assumption of Lemaitre strain equivalence and according to the extreme value characteristics of the normal stress-shear stress curve, the damage theory model of the fault fracture zone was reconstructed, and the microelement of fault was selected for analysis and divided into two parts, including damaged and undamaged materials. Finally, the results of the shaking table model tests were compared with the results of the shear cumulative damage model to verify the rationality of the theoretical model. Moreover, the predicted results of the theoretical model can better reflect the degradation trend of the fault fracture zone with the loading amplitude, normal stress, and loading times. It can be used as a reference for slope stability prediction under the action of cumulative static and dynamic loads.

Fatigue-Cumulative Damage Model of RC Crane Girders Strengthened with FRP Strips

2008 ◽  
Vol 385-387 ◽  
pp. 165-168
Author(s):  
Shan Suo Zheng ◽  
Bin Wang ◽  
Lei Li ◽  
Liang Zhang ◽  
Pi Ji Hou
Keyword(s):  
Damage Mechanics ◽  
Flexural Rigidity ◽  
Failure Process ◽  
Damage Model ◽  
Cumulative Damage ◽  
Good Time ◽  
Failure Patterns ◽  
Damage And Fracture ◽  
Cumulative Damage Model ◽  
Frp Strips

The cumulative damage of the reinforced concrete (RC) crane girders occurred by overload, fatigue and other reasons in service may deteriorate the safety of RC crane girders seriously, so it is necessary to analyze the damage mechanism and rationally reinforce them in good time. In this paper, RC crane girder strengthened with CFRP strips is taken as a target, and the mechanical performance degradation under fatigue load is studied. According to the basic theory of continuum damage mechanics, a damage variable is defined by flexural rigidity, and fatigue- cumulative damage model, which describes the process of damage and fracture, is established. The variation law of cumulative damage of RC crane girders strengthened with FRP strips under crane load is discussed, and the failure patterns such as concrete cracking, debonding between CFRP strips and concrete, yield of steel bars etc., are studied. The criterion which can be used to estimate the cumulative damage degree of strengthened RC crane girders is proposed. Finally, the evolution of the fatigue damage in the RC crane girders strengthened with CFRP strips is numerically simulated, and the results show that the proposed model can correctly describe the damage and failure process of strengthened RC crane girders. The research will provide a reference for the damage analysis and reinforcement of RC crane girders strengthened with CFRP strips.

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