A double cantilever beam incorporating cohesive crack modeling for superconductors

2020 ◽  
Vol 34 (15) ◽  
pp. 2050166 ◽  
Author(s):  
K. F. Wang ◽  
Y. Q. Wang ◽  
B. L. Wang ◽  
L. Zheng
Keyword(s):  
Cantilever Beam ◽  
Electromagnetic Force ◽  
Double Cantilever Beam ◽  
Crack Opening ◽  
Cohesive Crack ◽  
Opening Displacement ◽  
Cohesive Interface ◽  
Potential Applications ◽  
Space Solar Power ◽  
Separation Relation

In this paper, a double cantilever beam (DCB) specimen incorporating cohesive crack is developed for superconductors which have potential applications in high temperature superconducting cables in space solar power station. The cohesive interface is introduced along the crack front of the DCB model under electromagnetic force. The load-separation relation (i.e. the crack opening displacement) is used as the fracture mechanics parameter and the corresponding curves during fracture process are obtained and verified by the finite element numerical method. Results show that the presence of tensile electromagnetic force makes crack propagate easily. Superconductors with small cracks have good adaptability to the oscillation of magnetic fields while that with large cracks are easier to fracture during the descent of the magnetic field. In addition, the ductility ratio of the cohesive interface can significantly increase the fracture strength. The length of fracture zone decreases as the crack length increases.

Fracture toughness measurement of mild steels with reinforced-double-cantilever-beam specimen

1976 ◽  
Vol 11 (4) ◽  
pp. 195-201 ◽  
Author(s):  
C L Chow ◽  
R C Owen
Keyword(s):  
Fracture Toughness ◽  
Crack Propagation ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Graphical Representation ◽  
Crack Opening ◽  
Beam Specimen ◽  
Opening Displacement ◽  
Extension Force ◽  
Tension Testing

The fracture toughness of mild steels was successfully determined under monotonic and cyclic crack propagation. The conditions governing the valid measurement of fracture toughness were satisfied by r.d.c.b. (reinforced-double-cantilever-beam) specimens, and photomicrographic evidence and compliance measurements verified the yielding of the specimens during cracking confined to the crack tip. Measurements of fracture toughness of EN 24 (BS 970 817M40) steel were made on the r.d.c.b., c.o.d. (crack-opening displacement) and c.k.s. (standard tension testing) specimens and the results verified the validity of the r.d.c.b. testing method. The compliance measuring approach was used to determine the rate of fatigue crack propagation and was found satisfactory using the graphical representation based on change in crack extension force Δ G. It was observed that the grain size of the steel has definite effects on its fracture toughness.

Influence of the Crack Opening Rate on the Fracture Toughness of Plain Concrete

1985 ◽  
Vol 64 ◽  
Author(s):  
P. Rossi ◽  
C. Boulay ◽  
P. Acker ◽  
Y. Malier
Keyword(s):  
Fracture Toughness ◽  
Brittle Fracture ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Crack Opening ◽  
Plain Concrete ◽  
Elastic Behavior ◽  
Linear Elastic

ABSTRACTThree D.C.B. tests (Double Cantilever Beam) under different loading histories have shown that the applied crack opening rates can have an effect on the KIC fracture toughness values computed on the basis of linear elastic behavior of concrete. This assumption can be well justified for a certain range of crack opening rates, outside of which viscous phenomena must be taken in account. The concepts of ductile and brittle fracture appear then as related to the crack opening rate.

A NEW METHOD TO DETERMINE TENSILE-STRAIN SOFTENING CURVE OF QUASI-BRITTLE MATERIALS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Ruimei An ◽  
Shujin Duan ◽  
Quanmin Guo
Keyword(s):  
Crack Opening Displacement ◽  
Tensile Strain ◽  
Strain Softening ◽  
Crack Opening ◽  
Crack Problem ◽  
Brittle Materials ◽  
Cohesive Crack ◽  
New Method ◽  
Opening Displacement ◽  
Softening Curve

Based on weight integration to obtain a closed solution of cohesive crack problem, a new method is proposed to determine the tensile-strain softening curve (TSC) for quasi-brittle materials. The key technique is to determine the weight function by superposition of the solution with different fictitious crack lengths to satisfy a given crack opening displacement within cohesive crack surfaces. As an example, a central crack problem under uniform tension with given crack opening displacement in the fracture process zone (FPZ) was analyzed, the corresponding TSC was determined, and then the solution for stress and displacement field was obtained.

STRESS FUNCTION OF SIMPLY SUPPORTED CONCRETE BEAM WITH A FRACTURE PROCESS ZONE UNDER UNIFORM LOAD

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Shujin Duan ◽  
Quanmin Guo
Keyword(s):  
Boundary Conditions ◽  
Stress Function ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Crack Opening ◽  
Crack Problem ◽  
Cohesive Crack ◽  
Opening Displacement ◽  
Simply Supported

Based on the weight integration to obtain the closed solution of cohesive crack problem, a method is proposed to obtain the stress function of a simply supported beam under uniform distributed forces in this paper. The key technique is to determine the weight of several solutions of elastic mechanics problems to satisfy the given crack traction within the cohesive crack surfaces and the boundary conditions. The error degree of the function to satisfy the boundary conditions mainly depends on the number and the location of the selected points. In the formed fracture process zone, there is both the finite magnitude of stress concentration and the smooth closed-crack opening displacement. The FE numerical simulation is also carried out; its results are in good agreement with the present theoretical calculation results.

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