Cau 9 Lap cong thuc va neu ro muc dich, y nghia tinh truc so bo

* lap cong thuc tinh so bo duong kinh truc

tinh theo momen xoan

To= T/W0=T.16/(pi.d^3) <= [To]

suy ra d>= canbac3 ( 10T/( pi.[To])

hay d>= canbac3 ( T/(0,2.[To])

* muc dich va y nghia cua viec tinh so bo

- muc dich

tinh so bo truc nham lay co so de tinh tiep cac thong so khac tren truc nhu la kick thuoc cac doan truc khong nho hon kick thuoc so bo

phan tich luc va momen tac dung len so do truc ta ve dc bieu do momen , tu bieu do momen ta xac dinh duoc duong kinh cac doan truc thoat moan dk ben doi voi momenn lon nhat viec tinh so bo giup ta chon hop ly cac doan truc thoa man khanang chiiu tai trong nhu yeu cau

- y nghia

tinh toan so bo  duong kinh truc la khau dau tien va co bannhat trong tinh toan thiet ke truc tat ca cac thong so lien quan cua truc nhu cac CTM lap tren truc deu duoc tinh qua gia tu so bo nay

do truc can tinh toan lien quan chat che den cac chi tiet may khac len viec tinh so bo truc qua momen  xoan da don gian hon duoc viec tinh truc ma co ban la dam bao duoc su hoat dong cua cac chi tiet may khac va tai trong tac dung len truc. buoc tinh kiemngheim sau cung cho thay viec chon so bo co thoa man hay khong , khi do viec thay doi cac thong so so bo se don gian hon nhieu so voi viec tinh toan truc trong quan he chat che voi rat nhieu CTM khac