MBD Simulation on a Piston Assembly
MBD Simulation on a Piston Assembly
TITLE: MULTIBODY DYNAMICS SIMULATION USING SOLIDWORKS MBD ON A CRANK-PISTON ASSEMBLY
We have to design all the different parts of the cylinder piston arrangement separately.
The parts are as follows :
1.Piston Head
2.Gudgeon Pin (Wrist pin)
3.Connecting rod
4.End Cap
5.Crank
After designing all the parts we have to complete the assembly.
After giving correct mates, we can check our model by rotating the crankshaft with the help of the mouse, this must show the piston reciprocating.
Then motion analysis is being carried out where rotary motion (motor) is provided to the crank. There are total 4 contact pairs between the parts of the crank
piston assembly ( steel is applied as material ) and results are being obtained.
Geometry creation :
(Personal comment - only adding those points which make sense in this report, not every little detail which has been told in the video already)
1. All the parts are designed in Solidworks individually which have been shown in the video.
2. Some options should be carefully selected while designing, for eg.- the curved slot in the piston head and in crank as well, it should be done via the extruded cut option in which the ip side cut option must be chosen. ( This is done because the sketch was open I personally prefer to close the sketch so
we don't have to worry about it. )
3. Another important thing is that the llets should be given to every sharp corner for mostly if we take into account stress concentration at sharp corners and the simulation to be more precise.
4. All the mates have been told in the video. I had used width mate where we need a symmetric position of the part eg. - The wrist pin the piston.
Solidworks motion analysis-
1. After complete assembly, the SolidWorks motion is enabled.
2. Rotary motion is provided to the crank (2000 rpm).
3. Solid Body contact is done between the bodies that are in contact
There are total 4 contact pairs -
connecting rod and crank
end cap and crank
connecting rod and piston head
Piston and Wrist pin
1. Gravity is also enabled in a downward direction w.r.to the assembly.
2. Now the most important point is that we add precise contact and frames per second is increased to 7200 for the purpose that we don't want to miss any
peak values of the desired parameters and also so that the simulation is smooth and more accurate.
3. Tried results for more than 5 revolutions of the crank.
Different parts of assembly:
1.Wrist pin
In IC engines the Gudgeon pin(Wrist pin) connects the piston to the connecting rod, and provides a bearing for the connecting rod to pivot upon as the piston moves.
2.Crank
A crankshaft is a rotating shaft which (in conjunction with the connecting rods) converts reciprocating motion of the pistons into rotational motion. Crankshafts are commonly used in internal combustion engines and consist of a series of cranks and crankpins to which the connecting rods are attached.
3.Connecting rod
Connecting rod, is the part of piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converets the reciprocating motion of the piston into the rotation of the crankshaft. End cap is a part of connecting rod.
4.End cap
5. Piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the uid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
6.Assembly
Input parameters:
Case 1: 0 mm Offset
Case 2: 10 mm Positive Offset
Case 3: 10 mm Negative Offset
Procedure:
Creating 3D model of piston, crank, connecting rod , end cap.
Assembiling the 3D model by using constraints.
Using Multibody Dynamics to nd the Motion Analysis for Piston Assembly.
In this Input is given to the crank and motor is xed to the crank an it is roate at the constant speed of 50rpm in three different casese.
In this we are using motion study properties, 7200 frames per second, and using Precise contact.
Gravity parameteres at Y direction.
Fixing the contact type as solid bodies for Piston assembly and assigning material as STEEL, and calculating the motion analysis of Liner displacement of
piston.
Output:
Liner displacement of piston and angular velocity of crank at three diffrent cases.
Case 1: Wrist pin at offset of zero positon.
Liner displacement of piston.
Angular velocity of crank.
Animation link:
Case 2: Wrist pin at offset of 10mm positive.
Liner displacement of piston.
Angular velocity of crank.
Animation link:
Case 3: Wrist pin at offset of 10mm negative.
Liner displacement of piston.
Angular velocity of crank.
Animation link:
Super impose all the three conditions:
Results:
Liner displacement of piston
0 mm offset : 2.1988E+02
10mm positive : 2.2407E+02
10mm negative : 2.2789E+02
Liner displacement of piston is increased gradually at three different cases.
Angular velocity of crank position was not changed.
The values obtained by the graphs is attached in the file below:
https://drive.google.com/file/d/1LisK9dzXOc4Guh_B6EGxAAFwAp4lLavR/view?usp=sharing