Stress-strain state and stress intensity factor in the vicinity of crack-like defects under biaxial tension of a plate

2014 ◽  
Vol 55 (6) ◽  
pp. 1045-1054 ◽  
Author(s):  
A. A. Ostsemin ◽  
P. B. Utkin
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Strain State ◽  
Biaxial Tension ◽  
Stress Strain ◽  
Stress Strain State

An effective crack tip region finite element sub-model for fracture mechanics analysis

2017 ◽  
Vol 2 (87) ◽  
pp. 56-65 ◽  
Author(s):  
T.M. Lenkovskiy ◽  
V.V. Kulyk ◽  
Z.A. Duriagina ◽  
R.A. Kovalchuk ◽  
V.G. Topilnytskyy ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Strain State ◽  
Three Dimensional ◽  
Crack Tip ◽  
Stress Strain ◽  
Stress Strain State ◽  
Standard Specimens

Purpose: To create an effective in engineering strength calculation three-dimensional submodel of the near crack tip region in solids for hi-fidelity analysis of their stress-strain state by the finite element method. Design/methodology/approach: To create a volume near the crack tip, regular threedimensional 20-node prismatic isoparametric elements and 15-node special elements with edge length of 12.5 μm with shifted nodes in order to simulate the singularity of stress at the crack tip were used. Using these two types of elements, a cylindrical fragment of diameter of 100 μm was built. In its base is a 16-vertex polygon, and its axis is the crack front line. In the radial direction the size of the elements was smoothly enlarged by creating of 5 circular layers of elements, and in the axial direction 8 layers were created. For convenience of the sub-model usage, the cylindrical fragment was completed by regular elements to a cubic form with edge size 400 μm. For the sub-model approbation, the full-scale three-dimensional models of standard specimens with cracks were built. The stress intensity factor K at normal tension was calculated assuming small scale yielding conditions in a plane between 4th and 5th layers of special elements on the basis of analysis of displacement fields near the crack tip. Findings: An effective three-dimensional sub-model of the near crack tip region is proposed. The sub-model was used to obtain the dependence of the stress intensity factor on the relative crack length at normal tension for four types of standard specimens. The obtained dependences show excellent correlation with known analytical solutions. Research limitations/implications: The concept of finite element meshing at threedimensional modelling of the near crack tip region for high-fidelity stress-strain state analysis was generalized. A sub-model of the near crack tip region was created and used to determine the stress intensity factor at normal tension of four types of standard specimens. It is shown that the proposed methodology is effective for precise analysis of the stressstrain state of solids with cracks within the framework of linear fracture mechanics. Practical implications: By applying the generalized approach and the proposed threedimensional sub-model of the near crack tip region, one can determine the stress-strain state of structure elements and machine parts when analysing their workability by the finite element method. Originality/value: An effective finite-element sub-model for the stress-strain state analysis in the vicinity of the crack tip within the framework of the linear fracture mechanics is proposed.

Study of stress-strain state of plate with semi-elliptical and through cracks

2021 ◽  
pp. 15-18
Author(s):  
D. E. Tulin ◽  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Elastoplastic Deformation ◽  
Strain State ◽  
Elliptical Crack ◽  
Stress Strain ◽  
Stress Strain State ◽  
Suggested Keywords ◽  
Deformation Stress

The study of the elastic and elastoplastic stress-strain state of a plate with a semi-elliptical crack when changing its geometry has been carried out. The process of transition of a semi-elliptical crack into a through one was considered. Options of the stress-strain state were determined by means of the FEA method. An approximating dependence of the stress intensity factor on geometry of the plate is suggested. Keywords: strength, semi-elliptical crack, K-calibration, stress intensity factor, elastoplastic deformation, stress state intensity.

Finite elements analysis of the side grooved I-beam specimen for mode II fatigue crack growth rates determination

2018 ◽  
Vol 2 (86) ◽  
pp. 70-77
Author(s):  
T.M. Lenkovskiy ◽  
V.V. Kulyk ◽  
Z.A. Duriagina ◽  
L.V. Dzyubyk ◽  
V.V. Vira ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Transverse Shear ◽  
Strain State ◽  
Beam Specimen ◽  
Stress Strain ◽  
Stress Strain State ◽  
Crack Faces

Purpose: Carefully investigate the stress-strain state of the side grooved I-beam specimen with edge crack and determine the effect of crack length and crack faces friction on stress intensity factor at transverse shear. Design/methodology/approach: The finite element method was used to estimate the stress-strain state of I-beam specimen at transverse shear. For this purpose, a fullscale, three-dimensional model of the specimen was created, which precisely reproduces its geometry and fatigue crack faces contact. For the correct reproduction of the stress singularity at the crack tip, a special sub-model was used, which has been tested earlier in solving similar problems of fracture mechanics. In order to improve the accuracy of the calculations, for crack plane and cross-section of the specimen on the crack extension modeling, an algorithm for changing the crack length without changing the total number of elements in the model was developed and applied. Young's modulus and Poisson's ratio of structural steels were specified for the model material. The static loading of the model was realized assuming small scale yielding condition. The stress intensity factor was found through the displacement of nodes in the prismatic elements adjacent to the plane and the front of the crack. Findings: Mathematical dependences, which show an increase of stress intensity factor in the I-beam specimen with an increase in the crack length, and its decrease with an increase of crack faces friction factor at transverse shear, were established. The results are compared with the partial cases known from the literature and their good convergence was shown. Research limitations/implications: By analyzing the obtained graphical dependences, it is established that for relative crack lengths less than 0.4 there is a significant influence of the initial notch on the stress-strain state of the specimen, and for the lengths greater than 0.9 an influence of constrained gripping part took place. For this reason, all subsequent calculations were carried out in the range of relative crack length from 0.4 to 0.9, which represents the applicability range of the final calculation formula. Increasing of the crack faces friction factor from 0 to 1 monotonically reduces the stress at the crack tip. For a short crack, this effect is 1.5 times greater than for a long one, which is reflected by the calculation formula. Practical implications: Using the proposed calculation formula, one can calculate the stress intensity factor in the I-beam specimen, and to determine the crack growth resistance characteristics of structural steels at transverse shear. Originality/value: A new, easy-to-use in engineering calculations formula is proposed for stress intensity factor determination in the I-beam specimen at transverse shear. The formula takes into account crack faces friction for various crack lengths.

scholarly journals A Continuum Theory of Crack Shielding in Ceramics

1987 ◽  
Vol 54 (1) ◽  
pp. 54-58 ◽  
Author(s):  
M. Ortiz
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Constitutive Model ◽  
Closed Form ◽  
Applied Stress ◽  
Continuum Theory ◽  
Displacement Fields ◽  
Stress Strain ◽  
Macroscopic Crack

A phenomenological constitutive model is proposed which aims at describing the overall effect of microfracture in ceramics. Based on this model, the asymptotic stress, strain, and displacement fields at the tip of a stationary macroscopic crack are determined in closed form. The near-tip stress-intensity factor is computed and observed to be significantly smaller than the applied stress-intensity factor even for moderate amounts of damage.

scholarly journals Analysis of the fatigue cracks development in crane girders and assessment of their residual life

2018 ◽  
Vol 84 (7) ◽  
pp. 47-54
Author(s):  
V. V. Moskvichev ◽  
E. A. Chaban
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Strain State ◽  
Residual Life ◽  
Fatigue Cracks ◽  
Crack Tip ◽  
State Equations ◽  
Stress Strain ◽  
Stress Strain State ◽  
Specific Loading

The results of analysis of the residual life of crane girders with operational defects based on numerical studies of the stress-strain state, equations of limiting states, and kinetic dependences of the fatigue crack development, based on the criteria of deformation and fracture mechanics are presented. High level of wear of the fixed capital assets of engineering constructions and metal structures as well as operation of the facilities in beyond-design-basis terms contribute to origination of the emergency situations caused by damage accumulation. Crane girders operated under emergency conditions due to the fatigue cracks of different lengths present in the most dangerous zones of the beam wall with an eccentric application of crane load are studied. The results of the numerical experiment revealed the lines of tension intensity impact at the crack tip appeared at the upper zone of the wall at different values of the loading eccentricity attributed to the rail shift from the vertical axis of the beam. The dependence of the length of the fatigue crack and stress intensity in the crack tip on the number of load cycles of the beam is determined. To assess the bearing capacity of crane girders operated in emergency conditions, it is suggested to use the effective values of the stress intensity factors calculated for the specific loading conditions, taking into account the structural features of the beams, size of the fatigue cracks and their location in the crane girders. Proceeding from the results of analysis the diagrams which provide of the remaining residual life of crane girders with a crack are constructed. Using traditional methods of structure calculation for cyclic fracture toughness we developed and implemented the calculation algorithm for individual lifetime of the crane girders which includes the obligatory analysis of the stress-strain state of the crane girders with a crack at the upper zone of the wall.

Force analysis of the stress-strain state of the surface layer of Al 2O3‒TiCceramics with AlN and TiN coatings

2021 ◽  
pp. 64-69
Author(s):  
V. V. Kuzin ◽  
M. A. Volosova ◽  
M. Yu. Fedorov
Keyword(s):  
Surface Layer ◽  
Stress Intensity ◽  
Strain State ◽  
Computer Engineering ◽  
Structural Elements ◽  
Force Analysis ◽  
Force Load ◽  
Stress Strain ◽  
Stress Strain State ◽  
Tin Coatings

Regularities of stress-strain state of surface layer of Al2O3‒TiC-ceramics with AlN and TiN coatings under the action of force load are established using the methodology of computer engineering. The features of influence of AlN and TiN coatings on the nature of changes in the stress intensity in the surfaces of structural elements forming the surface layer of Al2O3‒TiC ceramics are determined. The formation of microstructural stress concentrators at the boundary of the AlN and TiN coatings with the initial ceramics is revealed.

scholarly journals Modeling the Contact Interaction of a Pair of Antagonist Teeth through Individual Protective Mouthguards of Different Geometric Configuration

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7331
Author(s):  
Anna Kamenskikh ◽  
Alex G. Kuchumov ◽  
Inessa Baradina
Keyword(s):  
Stress Intensity ◽  
Contact Interaction ◽  
Strain State ◽  
Maximum Level ◽  
Constant Thickness ◽  
Intensity Level ◽  
Stress Strain ◽  
Stress Strain State ◽  
Geometric Configurations ◽  
Wide Range

This study carried out modeling of the contact between a pair of antagonist teeth with/without individual mouthguards with different geometric configurations. Comparisons of the stress–strain state of teeth interacting through a multilayer mouthguard EVA and multilayer mouthguards with an A-silicon interlayer were performed. The influence of the intermediate layer geometry of A-silicone in a multilayer mouthguard with an A-silicon interlayer on the stress–strain state of the human dentition was considered. The teeth geometry was obtained by computed tomography data and patient dental impressions. The contact 2D problem had a constant thickness, frictional contact deformation, and large deformations in the mouthguard. The strain–stress analysis of the biomechanical model was performed by elastoplastic stress–strain theory. Four geometric configurations of the mouthguard were considered within a wide range of functional loads varied from 50 to 300 N. The stress–strain distributions in a teeth pair during contact interaction at different levels of the physiological loads were obtained. The dependences of the maximum level of stress intensity and the plastic deformation intensity were established, and the contact parameters near the occlusion zone were considered. It was found that when using a multilayer mouthguard with an A-silicone interlayer, there is a significant decrease in the stress intensity level in the hard tissues of the teeth, more than eight and four times for the teeth of the upper and lower teeth, respectively.

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