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Elastic-plastic analysis of crack opening displacement at crack center
Chinese
133
abstracts
The experimental results show that (I) X, of two thin sheet aluminum alloys are valid; they_ are of Lyl22c2(1), K, =226.18kg/mm”2 and K,,= and l?,, = 208.31 kg/mm”2 I?, = 201.39 kg/mm”* 234.55 kg/mm3” of Lc4 - cs; (2) the R-curves of the four thin sheet aluminum alloys are independent of the initial crack length of specimen; (3) for different initial crack lengths the crack growth Aa is not a constant.
REFERENCES [I] H.
Tada, P. C. Paris and G. R. Irwin, [2] S. Wu and W. Y. Huang, Elastic-plastic Aeronautical Institute (1979).
The Stress Analysis of Crack Handbook analysis of crack opening displacement
Del Research Corporation (1973). at crack center. Repf. No. 456. Nanjing
THE CALCULATION OF THE STRAIN ENERGY RELEASE RATES AND THE STRESS INTENSITY FACTORS FOR SEVERAL CRACK CONDITIONS
Nanjing
WEI-YANG Aeronautical
HUANC Institute,
China
Abstract-The calculation of the strain energy release rates and the s:ress intensity factors for several crack conditions by small deformation theory is discussed. (I) A penny-shaped crack of radius a is located in the plane joining two bounded dissimilar infinite plates. The crack surfaces are subjected to uniform pressure 4. The strain energy release rates are given as
where
D, and Dz are bending
rigidity of the plates. (2) A penny-shaped crack of radius a is located in the middel plane. The thickness of the plate is 2h. A pair of concentrated tensile forces P are normal to the crack surfaces. The stress intensity factor is given as
(3) A flat elliptical crack with major and minor semi-axes a and b is located in the middle plane. The thickness of the plate is 2h. The crack surfaces are subjected to uniform pressure q. When the crack is extended with a increasing but b remaining constant. the strain energy release rate is given as 2
G,=8D$
a2
(
5+2Ftg
a4 >
where n” = D(24/a4
t
16ya2h’+
24/b”)’
If we interchange u and b in the formula, then we can obtain the strain energy release rate of the flat elliptical crack with b increasing and a remaining constant. Also discussed is the calculation of energy release rates for a cracked bar. There is an initial curvature on the cracked surface. The bar is subjected to a compressive load. The calculation is based on the simple beam theory.
ELASTIC-PLASTIC ANALYSIS OF CRACK OPENING DISPLACEMENT AT CRACK CENTER SHEN WU and WEIYANG HUANG Nanjing Aeronautical Institute, China Abstract-By the elastic equation of crack tension panels specimens of finite width[l]
opening
displacement
at crack
center
for
center
cracked
(1)
I34
Chinese abstract5 where F $ = -0.071 -.- 0.535 zL! +0.169 2 ( > (W) (W)
2+0.020
g (W)
’ - 1.071
I&+
(l-8
and according to the concept of Irwin and D-M modes of treating the crack tip plastic Lone. we have obtained respectively the elastic-plastic equations of crack opening displacement at crack center for those specimens. They are
where
and (3) where
F
i
$secu=--0.071-0.535
2”secN (W
i
)
,+0.169
@seca (W
):
The applicable range of the equations (2) and (3) are e/c, + 2a/ W c: 0.8, which satisfies the condition of ~~/c~ ~0.8 in Kc test. Experimental results shows that they are coincident with the results of computation within the limit of 2u/ W c 0.4 and n/n, c 0.5.
REFERENCE Ill R. Tada, P. C. Paris and G. R. Irwin, The Stress Analysis 0) Cracks Handbook. Del Research Corporation (19731.
THE DETERMINATION OF QUALITY CONTROL CRITERIA OF FRACTURE RESISTANCE IN WELDING BASE METAL OF LOW-TEMPERATURE STEELS AT 40-190°C LING YUNC Shanghai Chemical Institute, China and CHOU WEI-YU Harbin Research Institute of Welding, China Abstract-The fracture resistance of low-temperature steel for pressure vessel contains at least both static load brittle fracture resistance and low-cycle fatigue fracture resistance. On the basis of the authors’ theory of strain concentration fracture strength and criteria of strain fracture at crack tip em = +, a new formula is presented for the fracture resistance:
Depending on strain level $4 and crack allowance ugB and ugF required for static load brittle fracture resistance as well as low-cycle fatigue fracture resistance. the corresponding minimal value of fracture
133
abstracts
The experimental results show that (I) X, of two thin sheet aluminum alloys are valid; they_ are of Lyl22c2(1), K, =226.18kg/mm”2 and K,,= and l?,, = 208.31 kg/mm”2 I?, = 201.39 kg/mm”* 234.55 kg/mm3” of Lc4 - cs; (2) the R-curves of the four thin sheet aluminum alloys are independent of the initial crack length of specimen; (3) for different initial crack lengths the crack growth Aa is not a constant.
REFERENCES [I] H.
Tada, P. C. Paris and G. R. Irwin, [2] S. Wu and W. Y. Huang, Elastic-plastic Aeronautical Institute (1979).
The Stress Analysis of Crack Handbook analysis of crack opening displacement
Del Research Corporation (1973). at crack center. Repf. No. 456. Nanjing
THE CALCULATION OF THE STRAIN ENERGY RELEASE RATES AND THE STRESS INTENSITY FACTORS FOR SEVERAL CRACK CONDITIONS
Nanjing
WEI-YANG Aeronautical
HUANC Institute,
China
Abstract-The calculation of the strain energy release rates and the s:ress intensity factors for several crack conditions by small deformation theory is discussed. (I) A penny-shaped crack of radius a is located in the plane joining two bounded dissimilar infinite plates. The crack surfaces are subjected to uniform pressure 4. The strain energy release rates are given as
where
D, and Dz are bending
rigidity of the plates. (2) A penny-shaped crack of radius a is located in the middel plane. The thickness of the plate is 2h. A pair of concentrated tensile forces P are normal to the crack surfaces. The stress intensity factor is given as
(3) A flat elliptical crack with major and minor semi-axes a and b is located in the middle plane. The thickness of the plate is 2h. The crack surfaces are subjected to uniform pressure q. When the crack is extended with a increasing but b remaining constant. the strain energy release rate is given as 2
G,=8D$
a2
(
5+2Ftg
a4 >
where n” = D(24/a4
t
16ya2h’+
24/b”)’
If we interchange u and b in the formula, then we can obtain the strain energy release rate of the flat elliptical crack with b increasing and a remaining constant. Also discussed is the calculation of energy release rates for a cracked bar. There is an initial curvature on the cracked surface. The bar is subjected to a compressive load. The calculation is based on the simple beam theory.
ELASTIC-PLASTIC ANALYSIS OF CRACK OPENING DISPLACEMENT AT CRACK CENTER SHEN WU and WEIYANG HUANG Nanjing Aeronautical Institute, China Abstract-By the elastic equation of crack tension panels specimens of finite width[l]
opening
displacement
at crack
center
for
center
cracked
(1)
I34
Chinese abstract5 where F $ = -0.071 -.- 0.535 zL! +0.169 2 ( > (W) (W)
2+0.020
g (W)
’ - 1.071
I&+
(l-8
and according to the concept of Irwin and D-M modes of treating the crack tip plastic Lone. we have obtained respectively the elastic-plastic equations of crack opening displacement at crack center for those specimens. They are
where
and (3) where
F
i
$secu=--0.071-0.535
2”secN (W
i
)
,+0.169
@seca (W
):
The applicable range of the equations (2) and (3) are e/c, + 2a/ W c: 0.8, which satisfies the condition of ~~/c~ ~0.8 in Kc test. Experimental results shows that they are coincident with the results of computation within the limit of 2u/ W c 0.4 and n/n, c 0.5.
REFERENCE Ill R. Tada, P. C. Paris and G. R. Irwin, The Stress Analysis 0) Cracks Handbook. Del Research Corporation (19731.
THE DETERMINATION OF QUALITY CONTROL CRITERIA OF FRACTURE RESISTANCE IN WELDING BASE METAL OF LOW-TEMPERATURE STEELS AT 40-190°C LING YUNC Shanghai Chemical Institute, China and CHOU WEI-YU Harbin Research Institute of Welding, China Abstract-The fracture resistance of low-temperature steel for pressure vessel contains at least both static load brittle fracture resistance and low-cycle fatigue fracture resistance. On the basis of the authors’ theory of strain concentration fracture strength and criteria of strain fracture at crack tip em = +, a new formula is presented for the fracture resistance:
Depending on strain level $4 and crack allowance ugB and ugF required for static load brittle fracture resistance as well as low-cycle fatigue fracture resistance. the corresponding minimal value of fracture