Integrated modelling method of bonding strength and residual life prediction for selective repair structure of aluminium alloy

2022 ◽  
pp. 095440622110631
Author(s):  
Yashi Liao ◽  
Xuhui Zhang ◽  
Zhineng Wang ◽  
Miaolei He
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Simulation Model ◽  
Bonding Strength ◽  
Residual Life ◽  
Integrated Modelling ◽  
Zone Method ◽  
Integrated Simulation ◽  
Utilisation Efficiency

To accurately describe and predict the overall strength and residual life of selective repair bonded structures, an integrated simulation model of crack propagation including bonding strength is established. Based on two methods, an integrated simulation model including a cohesive zone method model for predicting the residual life of a selective repair structure is established. By comparing the computational efficiency and accuracy of both the stress intensity factor and residual life of selective repair structures using different calculation methods, the modelling scheme is optimised. Based on this optimised scheme, the effect of adhesive thickness on the stress intensity factor and residual life of the repair structure is analysed. FM94 adhesive measuring 0.2–0.4 mm thickness is used to decrease the stress intensity factor and improve the remaining life such that material utilisation efficiency is guaranteed.

Parametric Equation of Stress Intensity Factor for Tubular K-joints under In-plane Bending Load

2005 ◽  
Vol 20 (2) ◽  
pp. 83-90 ◽  
Author(s):  
Y. B. Shao
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Surface Crack ◽  
Residual Life ◽  
Numerical Models ◽  
Accurate Estimation ◽  
Parametric Equation ◽  
Bending Load ◽  
Plane Bending

Stress intensity factor (SIF) is frequently used by designers to predict the integrity and residual life of a tubular joint containing a surface crack. In this study, a new numerical modelling method for cracked tubular K-joints has been presented. The proposed model has been verified from experimental results to be accurate and reliable in evaluation of the stress intensity factor for any tubular K-joint with a surface crack. Thereafter, parametric study for more than five thousand numerical models of tubular K-joints with a surface crack subjected to balanced in-plane bending load (IPB) has been carried out. A parametric equation to estimate the SIF value of any cracked tubular K-joint under IPB is then proposed based on the computed numerical results. Error analysis has been also carried out and it shows that the proposed equation can provide reliable and accurate estimation of the SIF value for cracked tubular K-joints under IPB.

Double cracks with single-inclusion fatigue propagation of surface-quenched large modulus rack

2019 ◽  
Vol 11 (12) ◽  
pp. 168781401989574
Author(s):  
Xionghao Cheng ◽  
Duanwei Shi ◽  
Chen Liu ◽  
Re Xia ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Residual Life ◽  
Moving Load ◽  
Normal Operation ◽  
Amplification Coefficient ◽  
Correction Coefficient ◽  
Single Crack ◽  
Spacing Ratio

A connectivity criterion based on the analysis of the stress intensity factor for the double cracks and inclusion was developed to study the residual life of large modulus crack. Applying the moving load, the finite element model in FRANC3D was proposed to study the variation law of the spacing ratio [Formula: see text] and stress intensity factor amplification coefficient [Formula: see text]. Also, the spacing ratio threshold and the initial spacing threshold for the law of propagation of the double cracks and inclusion were obtained. After the analysis of the threshold, the initial equivalent single crack [Formula: see text] was obtained based on the function [Formula: see text] and stress intensity factor for circular mode I crack [Formula: see text]. The final equivalent single crack [Formula: see text] was obtained by innovative use of the fatigue load cycle correction coefficient [Formula: see text]. Moreover, the residual fatigue life of surface-quenched large modulus rack is analyzed to be 55 years. It is revealed that the design of the large modulus crack is safe for the normal operation of the Three Gorges Shiplift.

Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

2020 ◽  
Vol 86 (10) ◽  
pp. 46-55
Author(s):  
S. I. Eleonsky ◽  
Yu. G. Matvienko ◽  
V. S. Pisarev ◽  
A. V. Chernov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Accumulation Process ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

A new type of cracks adding to Griffith–Irwin cracks

2019 ◽  
Vol 485 (2) ◽  
pp. 162-165
Author(s):  
V. A. Babeshko ◽  
O. M. Babeshko ◽  
O. V. Evdokimova
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Tip ◽  
Stress Concentrations ◽  
New Type

The distinctions in the description of the conditions of cracking of materials are revealed. For Griffith–Irwin cracks, fracture is determined by the magnitude of the stress-intensity factor at the crack tip; in the case of the new type of cracks, fracture occurs due to an increase in the stress concentrations up to singular concentrations.

scholarly journals New Approaches on the Stress Intensity Factor Characterization - Review

2020 ◽  
Vol 28 ◽  
pp. 226-233
Author(s):  
Behzad V. Farahani ◽  
Francisco Q. de Melo ◽  
Paulo J. Tavares ◽  
Pedro M.G.P. Moreira
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
New Approaches
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