biela ccmai

7/29/2019 biela CCMAI

1/13

Memoriu justificativ de calcul

Autoturism Dacia Logan 1.6 MCVDate tehnice

D= 79.5 mm

S= 80.5 mm

1.Dimensionare

1.1 Piciorul bielei

Constructia piciorului bielei este determinate in principal de tipul de imbinare

bolt-biela si bolt piston si de dimensiunile boltului.Dimensiuni caracteristice ale

piciorului bielei se stabilesc pe baza datelor statistice, modul de alegere a valoriloracestora fiind prezentat in tabelul 6.1.In cazul boltului fix in biela nu mai este nevoie de

bucsa, diametrul interior al piciorului b este egal (ca valoare nominala ) cu diametrul

exterior al boltului, di=d.Latimea piciorului b este identical cu lungimea de sprijin aboltului in piciorul bielei.

Alegem constructiv :m bolt fix in biela

m

Dimensionarea piciorului bielei in functie de diametrul exterior al boltului,d

1.2 Corpul bielei Dimensionarea corpului bielei

d 2:=

b 2:=

de 1.45d 31.9=:=

h 0.22d 4.84=:=

de 32:= m

h 5:= m

di 22:= m

H 0.32 D 25.44=:=

H 25.:= m


2/13

1.3 Capul bielei.Capul bielei este sectionat, iar capacul se imbina cu 2 suruburi.

Pentru reprezentare se va aproxima X =76

B 0.75 H 19.125=:=

B 19.:= m

B1 0.167H 4.259=:=

B1 4.:= m

H1 B1:=

H2 0.667H 17.009=:=

H2 17.:= m

R 0.15H 3.825=:=

R 4:= m

rS

240.25=:=

m

A 0.:=

LS

2 A134.167=:=

L 134.:= m

Hp 0.54de 17.28=:= m

Hc 1.23Hp 21.254=:= m

dm 0.62D 49.29=:=

lm 0.45dm 22.18=:=

dm 5:= m

lm 22.:= m

hi 1:= m

he

2:=

m

ds 0.1D 7.95=:= m

lc dm ds+ 2 hi+ 2g+ 63.45=:= m

Bc l:=

X lc ds+ 2 he+ 75.4=:= m


3/13

Verifica relatia

Verificarea rezistentei bielei

Biela este confectionata din 41CrNi12, iar boltul este fabricat din 15Cr08.

1.1 Verificarea piciorului bielei

D2

Bc2 76.25=

s 4:= m

X D2

Bc2

r 120:= MPa MPac 90:=

MParbolt 90:=

mp 0.40196:= kg

n 700:=

rot

min

n

30

733.038=:=

rad/s

Fi 103

mp r 2 1 A+( ):=

Fi 1. 13 1 03

=

N

pmax 5. 28 106:=

MPa

Fc D2

4pmax 10

3mp r

2 1 A+( ):=

Fc 262.1= N

re

de

216=:=

mri

di

211=:=

m

mrmp

re ri+( )2

13.5=:=


4/13

Verificarea la solicitarile datorare fortei de intindere

Rp R:=

8 deg:=

h re Rp+( ) cos ( ) ri Rp2

re Rp+( )2

sin ( ) sin ( ) 5.933=:=

110deg:= M0 103

Fi rmp 0.33 29.7( ) 443.409=:= N

N0 103

Fi 572 0.8 ( ) 644.624=:= N

M M0 N0 rmp 1 cos ( )( )+ Firmp

2 sin ( ) cos ( )( ):=

M 441.5=

Nm

N N0 cos ( )Fi

2sin ( ) cos ( )( )+ 503.693=:=

N

e 2 M6 rmp h+

h 2 rmp h+( ) N+

1

b h:=

MPae 539.3=

M'0

N'0 rmp sin ( )( ) Fcrmp

2 1 sin ( )( )

2

+

:=

N'0

M'0 sin ( ) N'0 rmp sin ( )2

sin 2 ( )

4 + Fc

rmp

8 2 ( ) 1 2 sin ( ) s in ( )+( ) 3 sin 2 ( )[ ] 0=M'0M'0

N '0 rm p s in ( )( ) Fcrm p

2 1 s in ( )( )

2

+

s in ( ) N '0 rm p s in ( )

2

sin 2 ( )

4 + Fc

rm p

8 2 ( ) 1 2s in ( ) s i n ( )+( ) 3 sin 2 ( )[ ]

=N '0N '0

N N'0 264.8=


5/13

Verificarea la solicitarile datorate fortei de compresiune

M'0 96.55= N

M' M'0 N'0 rmp 1 cos ( )( )+ Fcrmp

2 sin ( ) cos ( )

:=

M' 48.94= Nm

N' N'0 cos ( )Fc

2 sin ( ) cos ( )

+:=

NN' 90.555=

0.:=S0 6:= m

MPaE 2.1 10

4:=

gde

2di

2+

de2

di2

:=

j

d

i

2d

ib

2+

di2

dib2

:=

dib 1:= m

pf

S0

dig +

E

j

E+

:=

MPap

f191.1=

fe pf2 di

2

de2

di2

342.564=:=

MPamax e fe+ 881.864=:=


6/13

1.2 Verificarea corpului bielei

1:=

1t 20:=

1:=

0.1:=

0.9:=

MPa

MPamin 'e fe+ 342.281=:=

MPaamax min( )

2269.791=:=

MPammax min+( )

2612.073=:=

c

1t

a m+

:=

c 3.83=

kg

mm3 7.85106

:=

mm2

mp 1.5 bde

2di

2

2 0.28=:=

Fip 103

mp mp+( ) r 2

1 A+( ):=

NFip 197.:=

B1 0.167Hp 2.886=:= m

H1 B1:=

H2 0.667Hp 11.526=:= m

mm2

p H2 B1 2 B H1+ 145.805=:=


7/13

Este recomandat

pminFip

p:=

MPapmin 153.5= MPapmin 140 25..:=

Fcp D

2

4 pmax 10

3mp mp+( ) r

2 1 A+( ):=

Fcp 493.2= N

pmaxFcpp

:=

MPapmax 192.:=

MPa

apmax pmin( )

219.3=:=

mpmax pmin+( )

2172.8=:=

c1t

a m+

4.188=:=

dc dm 2 g+ 54.875=:=

MPa

0.9:=

m

mLi Ldi dc( )

2 150.938=:=

mm2 H2 B1 2 B H1+ 254.25=:=

m Li

6 p+ p+( ) 0.117=:=

kg


8/13

Fi 103 mp mp+ m+( ) r

2 1 A+( ):=

Fi 411.3= N

min

Fi

:=

MPa min 172.6=

Fc D

2

4 pmax 10

3mp mp+ m+( ) r

2 1 A+( ):=

NFc 503.7=

pr 90:=

MPa

z

Iz B H3 B B1( )

H23

12:=

Iz 3.212 105=

mm

2

max

1pr

2 E

L2

Iz

+

:=

MPa max 30.25=

y y

Iy2 H1 B

3

H2 B13

+12

3.589 103=:=

maxy

1pr

2 ELi

2

4Iy

+

0.011=:=

mm2


9/13

MPa

z

amax min( )

2:=

MPaa 84.675=

MPammax min+( )

2101.425=:=

0.9:=

c1t

a m+

:=

c 3.025=

y y

amaxy min( )

2:=

MPaa 83.165=

MPam

maxy min+( )2

86.305=:=

0.9:=

c1t

a m+

:=


10/13

1.3 Verificarea capului bielei

c 2.72=

mbc 1.5 Bc

X2 dm2

4 0.646=:= kg

mc mbc m mp 0.249=:= kg

Fic 103

mp mp+ m+ mc+( ) 1 A+( ) mbc+ r 2

:=

Fic 434.4= N

rmc

lc

231.37=:=

m

c 45 deg:=

M0 103

Fic rmc 0.83c 62( ):=

NM0 835.999=

N0 103

Fic 792 3 ( ) 341.543=:= N

Ic

Bc s3

12118.296=:=

mm2

Bcu 31:=

Icu

Bcu g3

1256.26=:=

mm2

Ac s Bc 88.722=:=

mm2

Acu s Bcu 124=:=

mm2

KM

Ic

Ic Icu+0.678=:=

KN

Ac

Ac Acu+0.417=:=


11/13

Alegem suruburi M8*1

Wc Bc s2

354.888=:=

mm2

ic KMM0

Wc

KNN0

Ac

+:=

MPa ic 286.3=

fc

1.5Fic lc3

106

E Ic Icu( )c 90( )

2:=

fc 0.983=

m

Fs

Fic

lc

:=

Fs 692.3= N

FT 3 Fs:=

FT 2.077 103=

N

C 3:= coeficientul decurgere al materialului

c 80:= MPa

ds

4 C FT

1.15 c:=

ds 6.32:= m

ds 6.91:= m

max4 FT

ds2

:=

max 172.3= MPa

min4 F0

ds2

21.289=:=

MPa

amax min( )

275.505=:=

MPa

mmax min+( )

296.795=:=

MPa

a

m0.78=


12/13

(1)

(2)

Deoarece (1) < (2) coeficientul de siguranta se va calcula cu relatia

Deoarece (1) < (2) coeficientul de siguranta se va calcula cu relatia

1t 36:= MPa

0.:=

1t

c ( )

11tc

0.818=

c

c

a

m+

4.56=:=

max4 FT

d02

73.455=:=

MPa

min4 F

0

d02

28.294=:=

MPa

amax min( )

222.581=:=

MPa

mmax min+( )

250.875=:=

MPa

a

m0.444=

(1)

cc

a

m+

:=


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