C. 4,35Q d 2,175n
c) Fe rt couvong tb0treachbonhaa::
Ferft c6 vong tu tre chU' nh$t d-gc d~c bi$t chu y trong ky thu$t may tfnh de lam b9 nhcJ. V$t li$u va cac san ph§m cua n6 c6 m9t lo9t yeu cau d~c bi$t. Be d~c tr- ng cho chung th- ong dung m9t vai tham so phy. Trang so nay phai ke den tham
so cc:1 ban cua h$ so chu' nh$t Ken cua chu tr1nh tU' tre, n6 la ti so giu'a cam Ctng tU' d- Bci- va cam Ctng tU' ldn nhat B~ax .
B
Ken =:_i!:!.!_
Bmax
De xac d!nh Bmax th- ong do n6 d trj so H~ax= 5Hk. H$ so Ken cang gan tdi 1 cang tot. Ferft tU' tre chU' nh$t khi sLI' d1:-tng can chu y den SL/ thay d6i tfnh chat cua
chung theo nhi$t d9. Vf d1:-t khi nhi$t d9 bien d6i tU' -20°C den 60°C th1 llfc khang tU' giam (1,5-,-- 2) Ian, cam Cmg tLI' giam (5-,-- 35)% .
.ft. ? A .A
CAU HOI 011\J T~P
1) Tr1nh bay khai ni$m viflt li$u tu? Neu cac d~c tfnh chU'a v$t li$u dan tu? 2) The nao la d- on~tap 19 tU' h6a? Tr1nh bay d- ong cong W h6a cua m9t so viflt
lieu W dien h1nh?
3) Tr1nh bay khai ni$m ve m9-ch tu? Neu cac each tfnh toan m9t so m9-ch W
dc:1n gian?
4) Neu cac d!nh luiflt co ban ve m9-ch tu? The nao la bai toan thuifln, bai toan nghjch?
5) TU' m9t m9-ch tU' hay ve ra so do thay the va neu cac d9-i I- c;5ng c6 trong so do?
6) Cho biet cac h- hong th- ong xay ra cua m9-ch tu?
7) The nao la v$t li$u W mem, W cung va viflt li$u W c6 c6ng d1:-1ng W d~c bi$t? 8) Neu tf nh chat cua thep la ky thuiflt di$n? Cach phan 109-i va giai thfch cac ky
hi$u cua thep la ky thu~H di$n?
9) Neu tfnh chat va c6ng d1:-1ng cua cac 109-i viflt li$u W da h9c?
BAI T~P Bai tap 4.1: Bai tap 4.1:
M9-ch W trong h1nh ve (h1nh BT: 4.1) c6 cac kfch th- de S = S8 = 9 cm2, 8 = 0,050 cm, Le= 30cm va N = 500 vong. Gia sU' nh- doi vbi sat µr = 70000.
a.tap ✓ xac d!nh tU' trd Reva R8• Gia sLI' m9-ch W lam vi$c tc;ii Be= 0, 1T.
b. Hay xac d!nh tLI' thong <J> va dong di$n I.
Bai tap 4.2:
Hinh BT: 4. 1
0oi v&i m<?ch tu trong (h1nh BT: 4.1 ). Hay xac d!nh: a. Tu cam L.
b. Nang 1-qng dLjtrCfw khi Be =1T.
c. 0i~n ap cam Ctng e. Cho tan so f= 6OHz, Bc=1,O sincot v&i co= 2n/6O=377.
Bai tap 4.3:
Cho rang v$t li~u cua 16i thep (h1nhBT: 4.1) c6 d- ang tu h6a nh- trong h1nh (h1nh BT: 4.2). Hay xac d[nh dong di~n I doi v&i.
H1nh BT: 2