BTE 1013 ENGINEERING SCIENCEs
-
Upload
carla-reed -
Category
Documents
-
view
33 -
download
0
description
Transcript of BTE 1013 ENGINEERING SCIENCEs
![Page 2: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/2.jpg)
What you will learn:
• Strength, elesticity, ductility, malleability, brittleness, toughness, hardness
• Ferrous/ non-ferrous metals, tensile stress, yield stress, shear force, percentage of elongation and percentage of reduction in plain carbon steel, shear force, bending moment and fatigue test
![Page 3: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/3.jpg)
7.1 Strength, elasticity, ductility, malleability, brittleness, toughness, hardness
7.2 Ferrous/non-ferrous metals, tensile stress, yield stress, shear force, percentage of elongation, percentage of reduction in plain carbon steel, shear force, bending moment and fatigue test
![Page 4: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/4.jpg)
• For practical purposes, components are designed to withstand forces and loads that a device is designed for and, so long as the instructions for use and maintenance, such as safe loads and tightening torques, are observed, problems should not be experienced.
Strength of materials
![Page 5: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/5.jpg)
Other terms used in describing materials
• Hardness• Toughness
![Page 6: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/6.jpg)
Hardness• A hard material is one that resists
indentation or abrasion by another material.
![Page 7: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/7.jpg)
Toughness• A material is said to be tough when a
large amount of energy is required to fracture it.
![Page 8: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/8.jpg)
Brittleness• Materials that break without undergoing
local distortion and are unable to withstand sharp blows are said to be brittle. Most types of cast iron are brittle.
![Page 9: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/9.jpg)
Ductility• A material that can be drawn out by
tensile force is said to be ductile. The steel sheet that is used in the construction of motor car panels is of a type known as deep drawing steel and this is a ductile material.
![Page 10: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/10.jpg)
Malleability• Metals that can hammered and bent
without cracking are said to be malleable. Lead is an example of a malleable material.
![Page 11: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/11.jpg)
Non-ferrous metals• These are mainly alloys that contain no iron.
Commonly used non-ferrous alloys are those made from copper, lead, tin, aluminium or magnesium. Non-ferrous alloys are used extensively in automotive engineering.
![Page 12: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/12.jpg)
Stress• Forces that tend to stretch, or pull something
apart, are known as tensile forces and they produce two important effects:
• 1. In trying to pull the bolt apart, internal resisting
• forces are created and these internal forces are
• known as stress.• 2. The length of the bolt will increase, and this
change in the bolt’s dimensions is known as strain.
• Stress is calculated by dividing the applied force
• by the cross-sectional area of the bolt.• Stress = Force/Cross-sectional area
![Page 13: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/13.jpg)
Types of stress• There are three basic forms of stress:
– 1. tensile stress;– 2. compressive stress;– 3. shear stress – torsional stress is a form of shear
stress.
![Page 14: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/14.jpg)
![Page 15: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/15.jpg)
![Page 16: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/16.jpg)
Examples of stress measure• Example 1: A cylinder head bolt with an
effective diameter of 15mm carries a tensile load of 10 kN. Calculate the tensile stress in the bolt.
![Page 17: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/17.jpg)
• Example 2: A connecting rod has a cross-sectional area of 200mm2 and it carries a compressive force of 2.4 tonnes. Calculate the compressive stress in the
• connecting rod.
![Page 18: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/18.jpg)
• Example 3: The hand brake linkage shown in Figure
• carries a tensile force of 600 N. Calculate the shear stress in the clevis pin, which is 12mm in diameter.
![Page 19: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/19.jpg)
• In this case the shearing action is attempting to shear the clevis pin across two cross-sectional areas.
![Page 20: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/20.jpg)
• Example 4: A propeller shaft coupling of a truck is secured by four bolts of 14mmdiameter that are equally spaced at a radius of 50mm from the centre of the propeller shaft. Calculate the shear stress in each bolt when the shaft is transmitting a torque of 500N m.
![Page 21: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/21.jpg)
![Page 22: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/22.jpg)
Strain• When a load is applied to a metal test bar a
change of shape takes place. A tensile load will stretch the bar and a compressive load will shorten it. This change of shape is called strain. The three basic types of strain are shown in Figure
![Page 23: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/23.jpg)
Example strain measure• A steel rod 200mm in length stretches by
0.12mm when it is subjected to a tensile load of 2 tonnes. Determine the strain.
• Solution• Strain = change in length/original length• = 0.12mm/200mm• Tensile strain in the steel rod = 0.0006
• Note: strain does not have any units.
![Page 24: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/24.jpg)
![Page 25: BTE 1013 ENGINEERING SCIENCEs](https://reader036.fdocuments.in/reader036/viewer/2022062517/56812eff550346895d949dbd/html5/thumbnails/25.jpg)
THANK YOU