soal sambungan las

Nama : Felix Ernest

NIM    : 1110623046

Tentukan ukuran pengelasan jika:

1. tegangan geser maksimum = 800 + (5 x digit terakhir NIM) kg/cm2
2.Beban = 4000 + (50 x digit terakhir NIM) Kg
3.Lebar plat = 20 + digit terakhir NIM cm
4. Tebal plta 15 cm
5. Panjang 40 cm

Jawaban

1. X =15t x 2 x 2,5 + 26t : 15t x 2 + 26t =  1,80 cm

2.Panjang lengan (e)
e = 40 + 15 – 1,80 = 53,2 cm

3.Momen inersia
I xx = 1/12 x t x 676 + 2 x 15t x 169  =1746,3 t cm4
I yy = 2 x (tx225)/12 + 2 x 15t (2,5 – 1,80)2 + 26t x 1,80 = 89,199t cm4
Momen inersia polar
IG = Ixx + Iyy = 1746,3t + 89,199t = 1835.49 t cm4

4.Radius pengelasan maksimum
R = = 18,52 cm
Cos Ɵ = r1 / r2 = 15-1,80 / 18,52 = 0.71

5.Primary shear stress
4300 : t x 15 + 26 = 91.08  / t Kg/cm2

6.Secondary shear stress
= 4300 x 53,2 x 18,52/ 1835,49t = 2308,13/t Kg/cm2

7.Resultan gaya geser
396900= (91,08/t)2 + (2308,7/t)2 + 2 x (91,08 /t) x (2308,7/t) x 0,71
t = 0,818 cm = 8,18 mm