MINGGU 4 STRESS ASD LSD TF2103 Mekanika Teknik

MINGGU 4 : STRESS ASD & LSD TF-2103 Mekanika Teknik (TA 2)

A. Distribution of dilatational structure orientations ▷ State of stress ▷ Fluid pressure B. Illustration of stochastic model (Yamaji, et al. , 2010) Fluid pressure condition (Faye et al, 2018) DPI=0, 12 DPI=0, 95 CONTEXT OF VEIN FORMATION? ALTERATION DISTRIBUTION 2

3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 3

Capaian Pembelajaran NÔRMAL STRESS Menguasai konsep SHEAR STRESS Menguasai konsep STRESS DESIGN 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 4

Design of a member for strength is based on selecting either an allowable stress or a factor of safety that will enable it to safely support its intended load (ASD) Design Criteria 1. design of aircraft or space-vehicle close to 1, to reduce the weight of the vehicle 2. a nuclear power plant, the factor of safety for may be as high as 3 due to uncertainties in loading or material behavior 3. approx. 1. 1 -1. 3 in mining (slope stability) 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 5

Design of a member for strength is by using load and resistance factors to modify the strength of the material and the load, respectively (LSD/LRFD) R (total loading) = 1. 2 D + 1. 6 L + 0. 5 S Resistance factors Φ (phi) material’s quality and the consistency of its strength for a steel member in tension 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) Design Criteria 6

When solving problems using the average normal and shear stress equations, a careful consideration should first be made as to choosing the section over which the critical stress is acting. Once this section is determined, the member must then be designed to have a sufficient area at the section to resist the stress that acts on it. Procedure for Analysis This area is determined using the following steps. Internal Loading : Section the member through the area and draw a free-body diagram of a segment of the member. The internal resultant force at the section is then determined using the equations. Required Area : Provided either the allowable stress or the load and resistance factors are known or can be determined, then the required area needed to sustain the calculated load or factored load at the section is determined from of equilibrium. 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 7

Here hurricane winds caused the failure of this highway sign. Assuming the wind creates a uniform pressure on the sign of 2 k. Pa, use reasonable dimensions for the sign and determine the resultant shear and moment at the two connections where the failure occurred. 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 8

The vertical load on the hook is 1000 lb. Draw the appropriate free-body diagrams and determine the maximum average shear force on the pins at A, B, and C. Note that due to symmetry four wheels are used to support the loading on the railing. 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 9

The long bolt passes through the 30 -mm-thick plate. If the force in the bolt shank is 8 k. N, determine the average normal stress in the shank, the average shear stress along the cylindrical area of the plate defined by the section lines a– a , and the average shear stress in the bolt head along the cylindrical area defined by the section lines b – b. 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 10

Chapter Review Stress 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 11

Capaian Pembelajaran Menguasai konsep NORMAL AND SHEAR STRAIN 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) Menguasai konsep DEFORMATION OF A BODY 12

Normal Strain line segments to elongate or contract The Average Normal Strain Shear Strain line segments change direction Shear Strain dimensionless quantity measured in radians (rad) 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 13

new length Cartesian Strain Components approximate angles between these sides normal strains cause a change in volume shear strains cause a change in its shape 3/11/2021 TA 2103 - Mekanika Teknik - TA 2 (LP 2020) 14

Terima Kasih Ketua Kelas : 119370100 Yan A. Ramadhan