Material Properties

2142-391 Engineering Mechanical LaboratoryAUTOMOTIVE DESIGN AND MANUFACTURING

International Program, Chulalongkorn University

Lecturer

Aj. Thanyarat SINGHANART (TSN)

Office room : AUTO. Bldg. 2nd floor, room 213

Brackgrounds

Brackgrounds

Challenger was destroyed in the second minute of STS-51-L, the orbiter's tenth mission, on January 28, 1986, when an O-ring seal on its right solid rocket booster (SRB) failed. The O-rings failed to seal due to a variety factors, including unusually cold temperatures. This failure allowed a plume of flame to leak out of the SRB and impinge on both the external fuel tank (ET) and SRB aft attachment strut. This caused both structural failure of the ET, and the SRB pivoted into the orbiter and ET. The vehicle assembly then broke up under aerodynamic loads.

O-ring

“Properties drop in low temperature”

Mathematical Models

EA

FLDeformation of Axially-Loaded Member

GJ

TLDeformation of Torsion Member

Deflection of Beam MEI

2

2

eCR L

EIF

Buckling

. . Y

allowable

S F

Safety Factor

Objectives

To study how to test the materials for obtaining the desired properties. Tensile test Hardness test Impact test

To study how to evaluate the mechanical properties of the materials.

Etc. （ Options) Can we relate the material properties to applications? Can we determine the tensile strength from the hardness value? Can we explain the fracture mechanism of ductile and brittle materials? etc.

STANDARD : Tensile test

STANDARD : Hardness test

STANDARD : Impact test

Testing Machines

Materials:- Construction Steel- Shaft Steel- Cast Iron- Aluminum- Brass

Stress-Strain Relationship

Data Reduction (Tensile Test)

Young’s Modulus

0.2% offset Yield Stress

Tensile Strength

% Elongation

% Reduction of Area

Modulus of Resilience

Modulus of toughness

Etc.

Hardness test

Materials:- Steel- Steel after hardening process

Impact test

Materials:- Steel- Aluminum- Brass

SEE YOU NEXT WEEK