Criteria S.I. Engine (Petrol or Spark Ignition Engine) C.I. Engine (Diesel or Compression Ignition Engine) Working Cycle Works on Otto Cycle or Constant Volume Cycle. Works on Diesel Cycle. Mixture During Suction Stroke Takes a mixture of air and petrol during the suction stroke. Takes only air during the suction stroke. Fuel Used Uses petrol as fuel. Uses diesel as fuel. Compression Ratio Has a compression ratio that varies from 6 to 10. Has a compression ratio that varies from 16 to 20. Engine Weight and Cost S.I. engines are lighter and cheaper. C.I. engines are heavier and costlier. Initial Cost Initial cost is lower compared to C.I. engines. Initial cost is high due to high compression ratio. Starting Starting is easy. Starting is difficult, especially in cold conditions. ...
STRESS STRAIN CURVE ( Tensile test for Ductile and Brittle Material)
Point O to A graph is a straight line which represent stress is proportional to strain.
2. )Elastic limit ( point B) - A to B the material will regain its original shape & Size When load is removed. The point B is khown as Elastic limit.
Elastic limit - it is a maximum limit of stress which a body sustain and regain its shape and size when load is removed
3.) Yield Point (Point C & D) - Beyond point B , the Plastic Stage will reach it means on removal of load the material will not be able to recover it's Original shape and size.There are also two yield Point C & D.
The point C is called Upper Yield Point.
The point D is called Lower Yield Point.
The stress corresponding to Yield Points is known as Yield stress.
4. ) Ultimate Stress ( Point E ) - At point D , The body regain some strength. The stress goes on increasing till point E is reached. At point E stress attains it's maximum value is known as Ultimate stress.
5.) Breaking stress ( Point F ) - At point F body could not take any load and is broken. The stress corresponding to point F.