ソリッド要素の場合、破壊ひずみもまた、Lode角を用いて定義された3次元応力ひずみに依存します。
これは、破壊ひずみをLode角パラメータの関数としてtable_ID1 1によって参照される/TABLE エンティティ内に追加することで含めることが可能です。シェル要素の場合は、破壊ひずみを応力軸性の関数として定義することだけが必要です。しかしながら、ソリッド要素の場合は、破壊ひずみを応力軸性とLode角の関数として含めると、より正確になります。
Radioss では、Lode角は、正規化され無次元のLode角パラメータ
ξ
を使って入力され、ここで定義されます。
あるポイント
P における応力状態は、主応力(
σ
1
,
σ
2
,
σ
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
Wdbiabeo8aZ9aadaWgaaWcbaWdbiaaigdaa8aabeaak8qacaGGSaGa
eq4Wdm3damaaBaaaleaapeGaaGOmaaWdaeqaaOWdbiaacYcacqaHdp
WCpaWaaSbaaSqaa8qacaaIZaaapaqabaaaaa@409E@
) で表されますが、応力不変量(
I
1
,
J
2
,
J
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaadMeapaWaaSbaaSqaa8qacaaIXaaapaqabaGcpeGaaiilaiaa
dQeapaWaaSbaaSqaa8qacaaIYaaapaqabaGcpeGaaiilaiaadQeapa
WaaSbaaSqaa8qacaaIZaaapaqabaaaaa@3DC1@
)を使って表すこともできます。応力不変量を用いる利点は、応力不変量が一定で座標系の向きに依存しない点にあります。
図 2 では、ポイント
P
σ
1
,
σ
2
,
σ
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
Wdbiabeo8aZ9aadaWgaaWcbaWdbiaaigdaa8aabeaak8qacaGGSaGa
eq4Wdm3damaaBaaaleaapeGaaGOmaaWdaeqaaOWdbiaacYcacqaHdp
WCpaWaaSbaaSqaa8qacaaIZaaapaqabaaaaa@409E@
の応力状態を応力不変量を使って正しく表すために、その大きさを次のように表します:
O
O
'
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHpbGaaC
4taiaacEcaaaa@38BA@
(1)
3
σ
m
=
3
3
I
1
ここで、
σ
m
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacqaHdpWCda
WgaaWcbaGaamyBaaqabaaaaa@3940@
平均応力
I
1
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaadMeapaWaaSbaaSqaa8qacaaIXaaapaqabaaaaa@3862@
第1応力不変量
I
1
=
σ
1
+
σ
2
+
σ
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaadMeapaWaaSbaaSqaa8qacaaIXaaapaqabaGcpeGaeyypa0Ja
ae4Wd8aadaWgaaWcbaWdbiaaigdaa8aabeaak8qacqGHRaWkcaqGdp
WdamaaBaaaleaapeGaaGOmaaWdaeqaaOWdbiabgUcaRiaabo8apaWa
aSbaaSqaa8qacaaIZaaapaqabaaaaa@4297@
O
O
'
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHpbGaaC
4taiaacEcaaaa@38BA@
は静水圧軸内にあり、これは、この軸内の主応力が同じ(
σ
1
=
σ
2
=
σ
3
)であることを意味しています。
|
O
O
'
|
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaabdaqaai
aah+eacaWHpbGaai4jaaGaay5bSlaawIa7aaaa@3BDC@
は静水圧です。
図 2. Pの応力状態
O
'
P
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHpbGaai
4jaiaahcfaaaa@38BB@
の大きさは:
(2)
2
J
2
=
2
3
σ
V
M
MathType@MTEF@5@5@+=
feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaadaGcaaqaai
aaikdacaWGkbWaaSbaaSqaaiaaikdaaeqaaaqabaGccqGH9aqpdaGc
aaqaamaalaaabaGaaGOmaaqaaiaaiodaaaaaleqaaOGaeq4Wdm3aaS
baaSqaaiaadAfacaWGnbaabeaaaaa@3F3B@
ここで、
J
2
MathType@MTEF@5@5@+=
feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGkbWaaS
baaSqaaiaaikdaaeqaaaaa@3815@
偏差応力
s
(
s
=
σ
-
p
)
MathType@MTEF@5@5@+=
feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWHZbWaae
WaaeaacaWHZbGaaCypaiaaho8acaWHTaGaaCiCaaGaayjkaiaawMca
aaaa@3DA3@
の第2不変量で、
J
2
=
1
2
(
S
1
2
+
S
2
2
+
S
3
2
)
=
1
2
[
(
σ
1
−
σ
2
)
2
+
(
σ
2
−
σ
3
)
2
+
(
σ
3
−
σ
1
)
2
]
MathType@MTEF@5@5@+=
feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaacaWGkbWaaS
baaSqaaiaaikdaaeqaaOGaeyypa0ZaaSaaaeaacaaIXaaabaGaaGOm
aaaacaGGOaGaam4uamaaBaaaleaacaaIXaaabeaakmaaCaaaleqaba
GaaGOmaaaakiabgUcaRiaadofadaWgaaWcbaGaaGOmaaqabaGcdaah
aaWcbeqaaiaaikdaaaGccqGHRaWkcaWGtbWaaSbaaSqaaiaaiodaae
qaaOWaaWbaaSqabeaacaaIYaaaaOGaaiykaiabg2da9maalaaabaGa
aGymaaqaaiaaikdaaaWaamWaaeaadaqadaqaaiabeo8aZnaaBaaale
aacaaIXaaabeaakiabgkHiTiabeo8aZnaaBaaaleaacaaIYaaabeaa
aOGaayjkaiaawMcaamaaCaaaleqabaGaaGOmaaaakiabgUcaRmaabm
aabaGaeq4Wdm3aaSbaaSqaaiaaikdaaeqaaOGaeyOeI0Iaeq4Wdm3a
aSbaaSqaaiaaiodaaeqaaaGccaGLOaGaayzkaaWaaWbaaSqabeaaca
aIYaaaaOGaey4kaSYaaeWaaeaacqaHdpWCdaWgaaWcbaGaaG4maaqa
baGccqGHsislcqaHdpWCdaWgaaWcbaGaaGymaaqabaaakiaawIcaca
GLPaaadaahaaWcbeqaaiaaikdaaaaakiaawUfacaGLDbaaaaa@66BC@
。
ポイント
P を特定するには、円形版内の角度が計算される必要があります。この角度が、Lode角
θ
と呼ばれます:
(3)
cos
(
3
θ
)
=
27
2
J
3
σ
V
M
3
=
3
3
2
J
3
J
2
3
/
2
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaabogacaqGVbGaae4Camaabmaapaqaa8qacaaIZaGaeqiUdeha
caGLOaGaayzkaaGaeyypa0ZaaSaaa8aabaWdbiaaikdacaaI3aaapa
qaa8qacaaIYaaaamaalaaapaqaa8qacaWGkbWdamaaBaaaleaapeGa
aG4maaWdaeqaaaGcbaWdbiabeo8aZ9aadaqhaaWcbaWdbiaadAfaca
WGnbaapaqaa8qacaaIZaaaaaaakiabg2da9maalaaapaqaa8qacaaI
ZaWaaOaaa8aabaWdbiaaiodaaSqabaaak8aabaWdbiaaikdaaaWaaS
aaa8aabaWdbiaadQeapaWaaSbaaSqaa8qacaaIZaaapaqabaaakeaa
peGaamOsa8aadaqhaaWcbaWdbiaaikdaa8aabaWdbiaaiodacaGGVa
GaaGOmaaaaaaaaaa@51E5@
ここで、
0
≤
θ
≤
π
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaaicdacqGHKjYOcqaH4oqCcqGHKjYOdaWcaaWdaeaapeGaeqiW
dahapaqaa8qacaaIZaaaaaaa@3F21@
で、
J
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaadQeapaWaaSbaaSqaa8qacaaIZaaapaqabaaaaa@3865@
は次のように計算される偏差応力の第3不変量:
(4)
J
3
=
S
1
S
2
S
3
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
WdbiaadQeapaWaaSbaaSqaa8qacaaIZaaapaqabaGcpeGaeyypa0Ja
ae4ua8aadaWgaaWcbaWdbiaaigdaa8aabeaak8qacaqGtbWdamaaBa
aaleaapeGaaGOmaaWdaeqaaOWdbiaabofapaWaaSbaaSqaa8qacaaI
Zaaapaqabaaaaa@3F7D@
/FAIL/TAB1 では、正規化され無次元であるLode角パラメータ
ξ
(範囲は
(
−
1
≤
ξ
≤
1
)
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
Wdbmaabmaapaqaa8qacqGHsislcaaIXaGaeyizIm6daiabe67a49qa
cqGHKjYOcaaIXaaacaGLOaGaayzkaaaaaa@3FD6@
)が使用され、次のように定義されます:
(5)
ξ
=
cos
(
3
θ
)
MathType@MTEF@5@5@+=
feaagKart1ev2aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn
hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr
4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9
vqaqpepm0xbbG8FasPYRqj0=yi0dXdbba9pGe9xq=JbbG8A8frFve9
Fve9Ff0dmeaabaqaciGacaGaaeqabaWaaeaaeaaakeaaqaaaaaaaaa
Wdbiabe67a4jabg2da9iaabogacaqGVbGaae4Camaabmaapaqaa8qa
caaIZaGaeqiUdehacaGLOaGaayzkaaaaaa@4031@
図 3. 異なるLode角と応力状態
Lode角
θ
およびLode角パラメータ
ξ
の特殊な特性を以下に示します:
Lode角パラメータ
ξ
Lode角
θ
応力状態
1
0
単軸引張+静水圧(3軸引張または軸対称引張)
0
30
純せん断 + 静水圧 (平面ひずみ)
-1
60
単軸圧縮 + 静水圧 (軸対称圧縮)
破壊ひずみサーフェスは、応力軸性およびLode角破壊データから生成できます。
図 4. 3次元破壊サーフェス
材料破壊サーフェスは、次の材料試験を用いて生成することができます。
図 5. 各種試験の応力状態とLode角
例 /TABLE ,dimension =3
破壊塑性-ひずみの入力 vs
table_ID 1 を用いた軸性、ひずみ速度、Lode角
/TABLE/1/4711
failure plastic-strain vs triaxiality and strain rate
#dimension
3
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
# FCT_ID strain_rate Lode_angle
3000 1E-4 -1
3001 0.1 0
3002 1.0 1
....
図 6. table_ID 1 が/TABLE を参照し、dimension =3の場合、破壊サーフェス