medoda diferentelor finite

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0 COMPLEMENTE DE TEORIA ELASTICITATII SI PLASTICITATII TEMA DE CASA Nr.1 METODA DIFERENTELOR FINITE STUDENT: TANASOIU PETRE-BOGDAN MASTER INGINERIE GEOTEHNICA, ANUL I PROFESOR: prof.univ.dr.ing. MIRCEA IEREMIA

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COMPLEMENTE DE TEORIA ELASTICITATII SI

PLASTICITATII

TEMA DE CASA Nr.1

METODA DIFERENTELOR FINITE

STUDENT: TANASOIU PETRE-BOGDAN

MASTER INGINERIE GEOTEHNICA, ANUL I

PROFESOR: prof.univ.dr.ing. MIRCEA IEREMIA

1

Metoda Numerica de Calcul a Diferentelor Finite

Sa se determine starea de eforturi unitare care apare in urmatoarea grinda perete si sa

se reprezinte grafic variatia pe inaltimea grinzii in diferite sectiuni a eforturilor unitare: ฯƒx, ฯƒy,

ฯ„xy.

Grinda-perete (diafragma) este din beton armat si este actionata in planul ei median de

un sistem de forte aflate in echilibru.

SCHEMA DE INCARCARE SCHEMA STATICA

Se va aborda rezolvarea numerica a problemei, discretinzandu-se domeniul grinzii-

perete, dupa care se va scrie cate o ecuatie algebrica liniara cu coeficienti constanti in fiecare

nod curent โ€œkโ€ al retelei de calcul folosite. In final se va rezolva un sistem algebric de 15

ecuatii cu 15 necunoscute.

Forma generala matriceala a sistemului de ecuatii algebrice este:

[A](15,15)*{F}(15,1)={B}(15,1), unde:

[A] โ€“ Matricea coeficientilor necunoscutelor (depinde de dimensiunile geometrice ale

grinzii-perete si de natura materialului din care e alcatuita grinda);

{F} โ€“ Matricea-coloana a functiilor necunoscute pe care urmeaza sa le aflam in fiecare

nod al retelei de calcul;

{B} โ€“ Matricea-coloana care depinde de modul de incarcare al grinzii-perete.

Analogia mecanica Aflarea functiei de tensiune pe conturul grinzii-perete si pe extracontur:

Contur: FK=MK , M โ€“ momentul incovoietor pe sistemul de baza static determinat;

Extracontur: FK=Fpc+2*a*N, N โ€“ forta axiala de pe sistemul de baza static determinat.

2

Diagramele de eforturi pe sistemul de baza

SISTEM DE BAZA DIAGRAMA N DIAGRAMA M

Caroiajul de calcul atasat grinzii Avand in vedere simetriile posibile, domeniul grinzii-perete poate fi discretizat astfel:

3

Definirea functiilor pe contur

F4โ€™=-6 qa

2

F3โ€™=-3.5 qa2

F2โ€™=-2 qa2

F1โ€™=-1.5 qa2

F16โ€™=-6 qa2

F15โ€™=-3 qa2

F14โ€™=-0.75 qa2

F13โ€™=0 qa2

Definirea functiilor pe extracontur

F4V=2*(-3)+F3โ€™= -9.5 qa

2

F3V=2*(-3)+F3= F3-6 qa2

F6V=2*(-3)+F6=F6-6 qa2

F9V=2*(-3)+F9=F9-6 qa2

F12V=2*(-3)+F12=F12-6 qa2

F15V=2*(-3)+F15=F15-6 qa2

F16V=2*(-3)+F15โ€™= -9 qa2

F40=2*(0)+F4โ€™=-6 qa2

F30=F3 qa2

F20=F2 qa2

F10=F1 qa2

F160=2*(0)+F16โ€™=-6 qa2

F150=F15 qa2

F140=F14 qa2

F130=F13 qa2

Reteaua fiind patratica, se va aplica molecula de calcul, in fiecare nod al

retelei:

4

Sistemul de ecuatii se obtine in felul urmator:

(impartit la qa2)

20*F1-8*(F1โ€™+F2+F4+F2)+2(F2โ€™+F5+ F2โ€™+F5)+1(F1O+F3+F7+F3)=0

20*F1-8*(-1.5+2*F2+F4)+2(-2*2+2*F5)+1(F1+2*F3+F7)=0

20*F1+12-16*F2-8F4+-8+4*F5+F1+2*F3+F7=0

21*F1-16*F2+2*F3-8*F4+4*F5+F7+4.0=0

21*F1-16*F2+2*F3-8*F4+4*F5+F7=-4.0

In mod analog se vor obtine celelalte ecuatii, iar sistemul va rezulta:

21*F1-16*F2+2*F3-8*F4+4*F5+F7=-4.0

22*F2-8*F1-8*F3+2*F4-8*F5+2*F6+F8=0

F1-8*F2+22*F3+2*F5-8*F6+F9=-42.0

4*F2-8*F1+20*F4-16*F5+2*F6-8*F7+4*F8+F10=1.5

2*F1-8*F2+2*F3-8*F4+21*F5-8*F6+2*F7-8*F8+2*F9+F11=8

2*F2-8*F3+F4-8*F5+21*F6+2*F8-8*F9+F12=-14.5

F1-8*F4+4*F5+20*F7-16*F8+2*F9-8*F10+4*F11+F13 =0

F2+2*F4-8*F5+2*F6-8*F7+21*F8-8*F9+2*F10-8*F11+2*F12+F14 =6

F3+2*F5-8*F6+F7-8*F8+21*F9+2*F11-8*F12+F15=-18

F4-8*F7+4*F8+20*F10-16*F11+2*F12-8*F13+4*F14 =0

F5+2*F7-8*F8+2*F9-8*F10+21*F11-8*F12+2*F13-8*F14+2*F15 =6.75

F6+2*F8-8*F9+F10-8*F11+21*F12+2*F14-8*F15 =-15

F7-8*F10+4*F11+21*F13-16*F14+2*F15 =3.0

F8+2*F10-8*F11+2*F12-8*F13+22*F14-8*F15 =6

F9+2*F11-8*F12+F13-8*F14+22*F15=-40.5

Matricea coeficientilor va fi de forma:

A

21

8

1

8

2

0

1

0

0

0

0

0

0

0

0

16

22

8

4

8

2

0

1

0

0

0

0

0

0

0

2

8

22

0

2

8

0

0

1

0

0

0

0

0

0

8

2

0

20

8

1

8

2

0

1

0

0

0

0

0

4

8

2

16

21

8

4

8

2

0

1

0

0

0

0

0

2

8

2

8

21

0

2

8

0

0

1

0

0

0

1

0

0

8

2

0

20

8

1

8

2

0

1

0

0

0

1

0

4

8

2

16

21

8

4

8

2

0

1

0

0

0

1

0

2

8

2

8

21

0

2

8

0

0

1

0

0

0

1

0

0

8

2

0

20

8

1

8

2

0

0

0

0

0

1

0

4

8

2

16

21

8

4

8

2

0

0

0

0

0

1

0

2

8

2

8

21

0

2

8

0

0

0

0

0

0

1

0

0

8

2

0

21

8

1

0

0

0

0

0

0

0

1

0

4

8

2

16

22

8

0

0

0

0

0

0

0

0

1

0

2

8

2

8

22

5

Matricea [A] este o matrice simetrica fata de diagonala principala. Pentru a exprima

mai bine acest fapt, se vor inmulti cu 2 urmatoarele randuri:

Rand: 2, 3, 5, 6, 8, 9, 11, 12, 14,15 rezultand urmatoarea matrice:

Matricea-coloana {B} a termenilor liberi are valoarea:

x2

x2

x2

x2

x2

x2

x2

x2

x2

x2

21 -16 2 -8 4 0 1 0 0 0 0 0 0 0 0

-16 44 -16 4 -16 4 0 2 0 0 0 0 0 0 0

2 -16 44 0 4 -16 0 0 2 0 0 0 0 0 0

-8 4 0 20 -16 2 -8 4 0 1 0 0 0 0 0

4 -16 4 -16 42 -16 4 -16 4 0 2 0 0 0 0

0 4 -16 2 -16 42 0 4 -16 0 0 2 0 0 0

1 0 0 -8 4 0 20 -16 2 -8 4 0 1 0 0

A= 0 2 0 4 -16 4 -16 42 -16 4 -16 4 0 2 0

0 0 2 0 4 -16 2 -16 42 0 4 -16 0 0 2

0 0 0 1 0 0 -8 4 0 20 -16 2 -8 4 0

0 0 0 0 2 0 4 -16 4 -16 42 -16 4 -16 4

0 0 0 0 0 2 0 4 -16 2 -16 42 0 4 -16

0 0 0 0 0 0 1 0 0 -8 4 0 21 -16 2

0 0 0 0 0 0 0 2 0 4 -16 4 -16 44 -16

0 0 0 0 0 0 0 0 2 0 4 -16 2 -16 44

B

4

0

42

1.5

8

14.5

0

6

18

0

6.75

15

3

6

40.5

B

4

0

84

1.5

16

29

0

12

36

0

13.5

30

3

12

81

6

Rezolvarea sistemului se va face folosind metoda matricei inverse, si anume se va

inmulti la stanga fiecare termen cu [A]-1

.

[A]*{F}={B}

[A]-1

*[A]*{F}=[A]-1

*{B}

{F}=[A]-1

*{B}

Efectuand calculele, va rezulta matricea {F}:

x qa2

A1

0.1092

0.0556

0.0168

0.0924

0.0606

0.0214

0.0589

0.0426

0.0159

0.0297

0.0222

0.0083

0.0094

0.007

0.0024

0.0556

0.062

0.0226

0.0603

0.0551

0.0228

0.0422

0.0357

0.0148

0.022

0.0179

0.0072

0.007

0.0055

0.002

0.0168

0.0226

0.0353

0.0207

0.0223

0.0209

0.015

0.0142

0.0096

0.0078

0.0068

0.0037

0.0024

0.002

0.0009

0.0924

0.0603

0.0207

0.2134

0.1319

0.0464

0.1621

0.1138

0.0426

0.089

0.0658

0.0249

0.0297

0.022

0.0078

0.0606

0.0551

0.0223

0.1319

0.1267

0.0505

0.1136

0.0988

0.0414

0.0658

0.0545

0.0225

0.0222

0.0179

0.0068

0.0214

0.0228

0.0209

0.0464

0.0505

0.054

0.0422

0.0412

0.0313

0.0249

0.0225

0.0135

0.0083

0.0072

0.0037

0.0589

0.0422

0.015

0.1621

0.1136

0.0422

0.2521

0.1621

0.0589

0.1621

0.1136

0.0422

0.0589

0.0422

0.015

0.0426

0.0357

0.0142

0.1138

0.0988

0.0412

0.1621

0.1512

0.0611

0.1138

0.0988

0.0412

0.0426

0.0357

0.0142

0.0159

0.0148

0.0096

0.0426

0.0414

0.0313

0.0589

0.0611

0.0593

0.0426

0.0414

0.0313

0.0159

0.0148

0.0096

0.0297

0.022

0.0078

0.089

0.0658

0.0249

0.1621

0.1138

0.0426

0.2134

0.1319

0.0464

0.0924

0.0603

0.0207

0.0222

0.0179

0.0068

0.0658

0.0545

0.0225

0.1136

0.0988

0.0414

0.1319

0.1267

0.0505

0.0606

0.0551

0.0223

0.0083

0.0072

0.0037

0.0249

0.0225

0.0135

0.0422

0.0412

0.0313

0.0464

0.0505

0.054

0.0214

0.0228

0.0209

0.0094

0.007

0.0024

0.0297

0.0222

0.0083

0.0589

0.0426

0.0159

0.0924

0.0606

0.0214

0.1092

0.0556

0.0168

0.007

0.0055

0.002

0.022

0.0179

0.0072

0.0422

0.0357

0.0148

0.0603

0.0551

0.0228

0.0556

0.062

0.0226

0.0024

0.002

0.0009

0.0078

0.0068

0.0037

0.015

0.0142

0.0096

0.0207

0.0223

0.0209

0.0168

0.0226

0.0353

F

1.4523

1.9645

3.4893

1.3272

1.8668

3.4519

1.1054

1.6902

3.3802

0.7634

1.4128

3.2642

0.3296

1.0497

3.1126

7

Verificarea ecuatiilor de conditie:

[A]*{F}={B}

Ecuatia 1: (simplificand qa2)

21*F1-16*F2+2*F3-8*F4+4*F5+F7=

=21*(-1.4523) - 16*(-1.9645) + 2*(-3.4893) - 8*(-1.3272) + 4*(-1.8668) +

0*(-3.4519) + 1*(-1.1054) + 0*(-1.6902) + 0*(-3.3802) + 0*(-0.7634)+ 0*(-1.4128)+

0*(-3.2642)+ 0*(-0.3296)+ 0*(-1.0497) + 0*(-3.1126) = -3.999999999999999999882

Ecuatia 7: (simplificand qa2)

F1-8*F4+4*F5+20*F7-16*F8+2*F9-8*F10+4*F11+F13 =

=1*(-1.4523) + 0*(-1.9645)+ 0*(-3.4893) - 8*(-1.3272) + 4*(-1.8668) +

0*(-3.4519) + 20*(-1.1054) -16*(-1.6902) + 2*(-3.3802) -8*(-0.7634)+ 4*(-1.4128)+

0*(-3.2642)+1*(-0.3296)+ 0*(-1.0497) + 0*(-3.1126) = -0.007

Ecuatia 10: (simplificand qa2)

F5+2*F7-8*F8+2*F9-8*F10+21*F11-8*F12+2*F13-8*F14+2*F15 =

=0*(-1.4523) + 0*(-1.9645) + 0*(-3.4893) + 0*(-1.3272) + 1*(-1.8668) +

0*(-3.4519) + 2*(-1.1054) -8*(-1.6902) + 2*(-3.3802) -8*(-0.7634)+ 21*(-1.4128)-

8*(-3.2642)+2*(-0.3296)-8*(-1.0497) +2*(-3.1126) = 6.7488

Ecuatia 13: (simplificand qa2)

F7-8*F10+4*F11+21*F13-16*F14+2*F15 =

=0*(-1.4523) + 0*(-1.9645) + 0*(-3.4893) + 0*(-1.3272) + 0*(-1.8668) +

0*(-3.4519) + 1*(-1.1054) +0*(-1.6902) + 0*(-3.3802) -8*(-0.7634)+ 4*(-1.4128)-

0*(-3.2642)+21*(-0.3296)-16*(-1.0497) +2*(-3.1126) = 3.0

Calculul Tensiunilor in interiorul grinzii-perete Tensiuni normale : ฯƒx

(ฯƒx)k =๐น๐‘™โˆ’2๐น๐‘˜+๐น๐‘—

๐›ฅ๐‘ฆ 2 , unde: Fj, Fk, Fl sunt valorile functiilor necunoscute, luate pe verticala

: ๐›ฅ๐‘ฆ=a

(ฯƒx)1โ€™ =๐น10 โˆ’2๐น1 โ€ฒ+๐น1

๐‘Ž2 = โˆ’1.4523 โˆ’2โˆ— โˆ’1.5 โˆ’1.4523 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.095 q

(ฯƒx)2โ€™ =๐น20 โˆ’2๐น2 โ€ฒ+๐น2

๐‘Ž2 = โˆ’1.9645โˆ’2โˆ— โˆ’2 โˆ’1.9645 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.071 q

(ฯƒx)3โ€™ =๐น30 โˆ’2๐น3 โ€ฒ+๐น3

๐‘Ž2 = โˆ’3.4893โˆ’2โˆ— โˆ’3.5 โˆ’3.4893 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.022 q

(ฯƒx)1 =๐น1 โ€ฒโˆ’2๐น1+๐น4

๐‘Ž2 = โˆ’1.5โˆ’2โˆ— โˆ’1.4523 โˆ’ 1.3272 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.077 q

(ฯƒx)2 =๐น2 โ€ฒโˆ’2๐น2+๐น5

๐‘Ž2 = โˆ’2โˆ’2โˆ— โˆ’1.9645 โˆ’1.8668 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.062 q

(ฯƒx)3 =๐น3 โ€ฒโˆ’2๐น3+๐น6

๐‘Ž2 = โˆ’3.5โˆ’2โˆ— โˆ’3.4893 โˆ’ 3.4519 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.027 q

8

(ฯƒx)4 =๐น1โˆ’2๐น4+๐น7

๐‘Ž2 = โˆ’1.4523 โˆ’2โˆ— โˆ’ 1.3272 โˆ’1.1054 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.097 q

(ฯƒx)5 =๐น2โˆ’2๐น5+๐น8

๐‘Ž2 = โˆ’1.9645โˆ’2โˆ— โˆ’1.8668 โˆ’1.6902 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.079 q

(ฯƒx)6 =๐น3โˆ’2๐น6+๐น9

๐‘Ž2 = โˆ’3.4893โˆ’2โˆ— โˆ’ 3.4519 โˆ’3.3802 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.034 q

(ฯƒx)7 =๐น4โˆ’2๐น7+๐น10

๐‘Ž2 = โˆ’ 1.3272 โˆ’2โˆ— โˆ’1.1054 โˆ’0.7634 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.120 q

(ฯƒx)8 =๐น5โˆ’2๐น8+๐น11

๐‘Ž2 = โˆ’1.8668 โˆ’2โˆ— โˆ’1.6902 โˆ’1.4128 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.081 q

(ฯƒx)9 =๐น6โˆ’2๐น9+๐น12

๐‘Ž2 = โˆ’ 3.4519โˆ’2โˆ— โˆ’3.3802 โˆ’3.2642 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.044 q

(ฯƒx)10 =๐น7โˆ’2๐น10 +๐น13

๐‘Ž2 = โˆ’1.1054 โˆ’2โˆ— โˆ’0.7634 โˆ’0.3296 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.092 q

(ฯƒx)11 =๐น8โˆ’2๐น11 +๐น14

๐‘Ž2 = โˆ’1.6902โˆ’2โˆ— โˆ’1.4128 โˆ’1.0497 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.086 q

(ฯƒx)12 =๐น9โˆ’2๐น12 +๐น15

๐‘Ž2 = โˆ’3.3802 โˆ’2โˆ— โˆ’3.2642 โˆ’3.1126 ๐‘ž๐‘Ž2

๐‘Ž2 = 0.036 q

(ฯƒx)13 =๐น10โˆ’2๐น13 +๐น13 โ€ฒ

๐‘Ž2 = โˆ’0.7634โˆ’2โˆ— โˆ’0.3296 + 0 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.104 q

(ฯƒx)14 =๐น11โˆ’2๐น14 +๐น14 โ€ฒ

๐‘Ž2 = โˆ’1.4128โˆ’2โˆ— โˆ’1.0497 โˆ’0.75 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.063 q

(ฯƒx)15 =๐น12โˆ’2๐น15 +๐น15 โ€ฒ

๐‘Ž2 = โˆ’3.2642โˆ’2โˆ— โˆ’3.1126 โˆ’3 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.039 q

(ฯƒx)13โ€™ =๐น13โˆ’2๐น13 โ€ฒ+๐น13๐‘‚

๐‘Ž2 = โˆ’0.3296โˆ’2โˆ— 0 โˆ’0.3296 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.659 q

(ฯƒx)14โ€™ =๐น14โˆ’2๐น14 โ€ฒ+๐น14๐‘‚

๐‘Ž2 = โˆ’1.0497โˆ’2โˆ— โˆ’0.75 โˆ’1.0497 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.599 q

(ฯƒx)15โ€™ =๐น15โˆ’2๐น15 โ€ฒ+๐น15๐‘‚

๐‘Ž2 = โˆ’3.1126 โˆ’2โˆ— โˆ’3 โˆ’3.1126 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.225 q

9

Tensiuni normale : ฯƒy

(ฯƒy)k =๐น๐‘˜+1โˆ’2๐น๐‘˜+๐น๐‘˜โˆ’1

๐›ฅ๐‘ฅ 2 , unde: Fk+1, Fk, Fk-1 sunt valorile functiilor necunoscute, luate pe

orizontala

: ๐›ฅ๐‘ฅ=a

(ฯƒy)1โ€™ =๐น2 โ€ฒโˆ’2๐น1 โ€ฒ+๐น2 โ€ฒ

๐‘Ž2 = โˆ’2โˆ’2โˆ— โˆ’1.5 โˆ’2 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.000 q

(ฯƒy)2โ€™ =๐น3 โ€ฒโˆ’2๐น2 โ€ฒ+๐น1 โ€ฒ

๐‘Ž2 = โˆ’3.5โˆ’2โˆ— โˆ’2 โˆ’1.5 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.000 q

(ฯƒy)3โ€™ =๐น4 โ€ฒโˆ’2๐น3 โ€ฒ+๐น2 โ€ฒ

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3.5 โˆ’2 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.000 q

(ฯƒy)1 =๐น2โˆ’2๐น1+๐น2

๐‘Ž2 = โˆ’1.9645โˆ’2โˆ— โˆ’1.4523 โˆ’1.9645 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.024 q

(ฯƒy)2 =๐น3โˆ’2๐น2+๐น1

๐‘Ž2 = โˆ’3.4893โˆ’2โˆ— โˆ’1.9645 โˆ’1.4523 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.013 q

(ฯƒy)3 =๐น4 โ€ฒโˆ’2๐น3+๐น2

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3.4893 โˆ’1.9645 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.986 q

(ฯƒy)4 =๐น5โˆ’2๐น4+๐น5

๐‘Ž2 = โˆ’1.8668 โˆ’2โˆ— โˆ’ 1.3272 โˆ’1.8668 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.079 q

(ฯƒy)5 =๐น6โˆ’2๐น5+๐น4

๐‘Ž2 = โˆ’ 3.4519โˆ’2โˆ— โˆ’1.8668 โˆ’ 1.3272 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.045 q

(ฯƒy)6 =๐น4 โ€ฒโˆ’2๐น6+๐น5

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’ 3.4519 โˆ’1.8668 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.963 q

(ฯƒy)7 =๐น8โˆ’2๐น7+๐น8

๐‘Ž2 = โˆ’1.6902โˆ’2โˆ— โˆ’1.1054 + โˆ’1.6902 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.170 q

(ฯƒy)8 =๐น9โˆ’2๐น8+๐น7

๐‘Ž2 = โˆ’3.3802 โˆ’2โˆ— โˆ’1.6902 โˆ’1.1054 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.033 q

(ฯƒy)9 =๐น4 โ€ฒโˆ’2๐น9+๐น8

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3.3802 +โˆ’1.6902 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.930 q

(ฯƒy)10 =๐น11โˆ’2๐น10 +๐น11

๐‘Ž2 = โˆ’1.4128 โˆ’2โˆ— โˆ’0.7634 โˆ’1.4128 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.300 q

(ฯƒy)11 =๐น12โˆ’2๐น11 +๐น10

๐‘Ž2 = โˆ’3.2642 โˆ’2โˆ— โˆ’1.4128 โˆ’0.7634 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.202 q

(ฯƒy)12 =๐น4 โ€ฒโˆ’2๐น12 +๐น11

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3.2642 โˆ’1.4128 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.884 q

(ฯƒy)13 =๐น14โˆ’2๐น13 +๐น14

๐‘Ž2 = โˆ’1.0497โˆ’2โˆ— โˆ’0.3296 โˆ’1.0497 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.440 q

(ฯƒy)14 =๐น15โˆ’2๐น14 +๐น13

๐‘Ž2 = โˆ’3.1126 โˆ’2โˆ— โˆ’1.0497 โˆ’0.3296 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.343 q

10

(ฯƒy)15 =๐น4 โ€ฒโˆ’2๐น15 +๐น14

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3.1126 โˆ’1.0497 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.825

(ฯƒy)13โ€™ =๐น14 โ€ฒโˆ’2๐น13 โ€ฒ+๐น14 โ€ฒ

๐‘Ž2 = โˆ’0.75โˆ’2โˆ— 0 โˆ’0.75 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.500 q

(ฯƒy)14โ€™ =๐น15 โ€ฒโˆ’2๐น14 โ€ฒ+๐น13 โ€ฒ

๐‘Ž2 = โˆ’3โˆ’2โˆ— โˆ’0.75 โˆ’0 ๐‘ž๐‘Ž2

๐‘Ž2 = -1.500 q

(ฯƒy)15โ€™ =๐น16 โ€ฒโˆ’2๐น15 โ€ฒ+๐น14 โ€ฒ

๐‘Ž2 = โˆ’6โˆ’2โˆ— โˆ’3 โˆ’0.75 ๐‘ž๐‘Ž2

๐‘Ž2 = -0.75 q

Tensiuni tangentiale : ฯ„xy

(ฯ„xy)k = ๐น๐‘™โˆ’1+๐น๐‘— +1 โˆ’(๐น๐‘™+1+๐น๐‘—โˆ’1)

4โˆ—๐›ฅ๐‘ฅ โˆ—๐›ฅ๐‘ฆ , unde: Fj-1, Fj+1, Fl-1, Fl+1 sunt valorile functiilor

necunoscute in jurul punctului k

: ๐›ฅ๐‘ฆ = ๐›ฅ๐‘ฅ=a

(ฯ„xy)1โ€™ = ๐น2๐‘‚+๐น2 โˆ’(๐น2๐‘‚+๐น2)

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)2โ€™ = ๐น3๐‘‚+๐น1 โˆ’(๐น1๐‘‚+๐น3)

4โˆ—๐‘Ž2 = โˆ’3.4893โˆ’1.4523 โˆ’(โˆ’1.4523 โˆ’3.4893 )

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)3โ€™ = ๐น4๐‘‚+๐น2 โˆ’(๐น2๐‘‚+๐น4 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.9645 โˆ’(โˆ’1.9645โˆ’6)

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)1 = ๐น2 โ€ฒ+๐น5 โˆ’(๐น2 โ€ฒ+๐น5)

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)2 = ๐น3 โ€ฒ+๐น4 โˆ’(๐น1 โ€ฒ+๐น6)

4โˆ—๐‘Ž2 = โˆ’3.5โˆ’ 1.3272 โˆ’(โˆ’1.5โˆ’ 3.4519 )

4โˆ—๐‘Ž2 =0.031 q

(ฯ„xy)3 = ๐น4 โ€ฒ+๐น5 โˆ’(๐น2 โ€ฒ+๐น4 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.8668 โˆ’(โˆ’2โˆ’ 6)

4โˆ—๐‘Ž2 =0.033 q

(ฯ„xy)4 = ๐น2+๐น8 โˆ’(๐น2+๐น8)

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)5 = ๐น3+๐น7 โˆ’(๐น1+๐น9)

4โˆ—๐‘Ž2 = โˆ’3.4893โˆ’1.1054 โˆ’(โˆ’1.4523 โˆ’3.3802 )

4โˆ—๐‘Ž2 =0.060 q

(ฯ„xy)6 = ๐น4 โ€ฒ+๐น8 โˆ’(๐น2+๐น4 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.6902 โˆ’(โˆ’1.9645โˆ’6)

4โˆ—๐‘Ž2 =0.069 q

11

(ฯ„xy)7 = ๐น5+๐น11 โˆ’(๐น5+๐น11 )

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)8 = ๐น6+๐น10 โˆ’(๐น4+๐น12 )

4โˆ—๐‘Ž2 = โˆ’ 3.4519โˆ’0.7634 โˆ’(โˆ’ 1.3272 โˆ’3.2642 )

4โˆ—๐‘Ž2 =0.094 q

(ฯ„xy)9 = ๐น4 โ€ฒ+๐น11 โˆ’(๐น5+๐น4 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.4128 โˆ’(โˆ’1.8668 โˆ’6)

4โˆ—๐‘Ž2 =0.114 q

(ฯ„xy)10 = ๐น8+๐น14 โˆ’(๐น8+๐น14 )

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)11 = ๐น9+๐น13 โˆ’(๐น7+๐น15 )

4โˆ—๐‘Ž2 = โˆ’3.3802 โˆ’0.3296 โˆ’(โˆ’1.1054 โˆ’3.1126 )

4โˆ—๐‘Ž2 =0.127 q

(ฯ„xy)12 = ๐น4โ€ฒ+๐น14 โˆ’(๐น8+๐น4 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.0497 โˆ’(โˆ’1.6902โˆ’6)

4โˆ—๐‘Ž2 =0.160 q

(ฯ„xy)13 = ๐น11 +๐น14 โ€ฒ โˆ’(๐น11 +๐น14 โ€ฒ)

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)14 = ๐น12 +๐น13 โ€ฒ โˆ’(๐น10 +๐น15 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’3.2642 +0 โˆ’(โˆ’0.7634 โˆ’3)

4โˆ—๐‘Ž2 =0.125 q

(ฯ„xy)15 = ๐น4โ€ฒ+๐น14 โ€ฒ โˆ’(๐น11 +๐น16 โ€ฒ)

4โˆ—๐‘Ž2 = โˆ’6โˆ’0.75 โˆ’(โˆ’1.4128 โˆ’6)

4โˆ—๐‘Ž2 =0.166 q

(ฯ„xy)13โ€™ = ๐น14 +๐น14๐‘‚ โˆ’(๐น14 +๐น14๐‘‚ )

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)14โ€™ = ๐น15 +๐น13๐‘‚ โˆ’(๐น13 +๐น15๐‘‚ )

4โˆ—๐‘Ž2 = โˆ’3.1126 โˆ’0.3296 โˆ’(โˆ’0.3296โˆ’3.1126 )

4โˆ—๐‘Ž2 =0 q

(ฯ„xy)15โ€™ = ๐น4 โ€ฒ+๐น14๐‘‚ โˆ’(๐น14 +๐น16๐‘‚ )

4โˆ—๐‘Ž2 = โˆ’6โˆ’1.0497 โˆ’(โˆ’1.0497โˆ’6)

4โˆ—๐‘Ž2 =0 q

12

13

14