Question

1. We need to glue two pieces of metal together to form a bar which will be under a state of stress of: [100 201 20] MPa 20 501 in a plane with normal vector along x If the glued section makes an angle of 120° with x, use Cauchy's law to: a) Find the traction force on the glued surface. (10 points) b) Find the normal stress on the glued surface. (10 points) c) Find the shear stress on the glued surface. (10 points) d) By referring to the table, and assuming all other properties of the glues are the same, choose one glue that best suits to be used in this condition. Use safety factor to explain your selection. (10 points) Glue Oy 120° Oy OY Shear Strength 15 MPa Table: Type Glue Normal Strength Type 1 120 MPa Type 2 100 MPa Type 3 140 MPa Type 4 150 MPa 50 MPa 45 MPa 10 MPa

Answer 1

100 20 r 20 СУ 50 any on on =100 MPa = 50 mpa mala 20 Hea - Eny + Tny sno 2 lon-by) Sm2o + Cos 20 Ex'y' Oni= contry) contry) + (n - 2) (6520 + Try og! Contry) ion-by) wsze - Eny Sinzo on tan coseco +exy 6 = 30° (from verticle) 75 +256 + 200 / 75 - 25 - 2011 104.82 MPa (1 on Something - 45:179 mpa = 2 Enly! -252 2011/ =-11-650 m pa (9 Traction force on glue = Area xłn'y' A + Zn'y' cosao A X 11.650x2 V3 = 13.45 where A is cross section area of Dar,

(6) Normal stress on glue 104.82 mpa shear stress en glue =-11.6.50 mla Co (d) 2 Type 2 glue will fail because Normal strength <104.82 Type u glue will also fand because shear strength < 11.6570 Comparison blw Tyret Normal Shear Type(Glue) (FOS) 120 104.82 140 us 104.82 11.650 we see thert Type 3 glue is safer then other glues. and Type 3 15 11.650 1 3 con