Experimental methods for fracture toughness measurement

1975 ◽  
Vol 10 (4) ◽  
pp. 225-232 ◽  
Author(s):  
A H Priest
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Plane Strain Fracture Toughness ◽  
Opening Displacement ◽  
Testing Procedures ◽  
Monitoring Technique ◽  
Fracture Toughness Measurement ◽  
Strain Fracture ◽  
Crack Monitoring ◽  
Toughness Measurement

Recommended methods for measuring fracture toughness parameters are discussed. The relevant Draft British Standards are: (a) Draft for Development 3:1971 ‘Methods for Plane Strain Fracture Toughness ( KI c) Testing’. (b) Draft for Development 19:1972 ‘Methods for Crack Opening Displacement (COD) Testing’. These documents are being revized and updated for publishing as full British Standards and any significant additions and alterations are noted. The situation with respect to non-standard tests is reviewed. The fracture toughness parameters under this heading include JI c, equivalent energy values, fracture propagation energy values and R-curve analysis. Particular attention is paid to the influence of strain rate on testing procedures and a crack monitoring technique is discussed.

Fracture Toughness Determinations of A-302B and Ni-Mo-V Steels With Various Size Specimens

1966 ◽  
Vol 88 (4) ◽  
pp. 783-791 ◽  
Author(s):  
D. F. Mowbray ◽  
A. J. Brothers ◽  
S. Yukawa
Keyword(s):  
Fracture Toughness ◽  
Crack Opening ◽  
Bend Angle ◽  
Opening Displacement ◽  
Fatigue Precrack ◽  
Strain Fracture ◽  
Shear Lip ◽  
Angle Crack ◽  
Fracture Tests ◽  
Increasing Temperature

Fracture tests were conducted on three steels obtained from heavy-section pieces over a range of test temperatures using single-edge notched (SEN) specimens under tensile loading and notched-bar (NB) specimens in bending. The SEN tests were performed on specimens 0.125 and 0.4 in. thick plus a few specimens 0.020 in. thick. In the NB series Charpy-sized specimens (0.4 in. square) were tested at various temperatures with additional tests on smaller and larger specimens up to 6 in. square at selected temperatures. All specimens were provided with a fatigue precrack at the tip of the notch. The tests were conducted to determine the capability of various size specimens for providing valid plane-strain fracture toughness (GIc or KIc) values at various temperatures for these steels. At very low temperatures all specimens gave similar KIc values. With increasing temperature, KIc values obtained from the larger specimens remained relatively constant and then increased rapidly. At higher temperatures within this range, valid KIc values could not be measured with small specimens. Two possible methods of estimating KIc at these temperatures from small specimen data are discussed. One of these involves a correlation between fracture toughness and shear-lip thickness. The second makes use of a relation between bend angle, crack-opening-displacement, and fracture toughness. The test results are analyzed to show that both methods can be very useful.

scholarly journals A Study of the Dynamic Plane Strain Fracture Toughness of Concrete by SHPB

2008 ◽  
Vol 385-387 ◽  
pp. 21-24 ◽  
Author(s):  
Jia Qu ◽  
Guang Ping Zou
Keyword(s):  
Fracture Toughness ◽  
Plane Strain ◽  
Dynamic Loads ◽  
Bending Test ◽  
Plane Strain Fracture Toughness ◽  
Three Dimensional Model ◽  
Response Curves ◽  
Opening Displacement ◽  
Strain Fracture ◽  
Dynamic Plane

Concrete is a type of engineering composites which is widely used in military and civil structures. The static performance of concrete can not be used to estimate the variation of concrete under high strain rates under dynamic loads. By introducing the three point bending test under static and dynamic loads, the plane strain fracture toughness KIC and KId were measured. Using the application of experimental-numerical method a three-dimensional model has been established by FEM software Ansys/LS-DYNA, to carryout transient analysis, and the response curves of stress intensity factor-time through the opening displacement of fracture. Thus, with obtaining the cracking time by the method of strain-gauge, the dynamic plane strain fracture toughness KId can be determined. By comparing KIc and KId we could conclude the result which meant concrete was more liable to crack under dynamic load.

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