Week - 1 - Consistency of Units
AIM
LS-DYNA doesn't have a default system of units. We have to input material properties and physical dimensions according to a consistent system of units as per our choice. This warrants that to use LS-DYNA in different circumstances, users has to be conversant with converting quantities from one system of units to another.
And also write a detailed report on unit conversion with calculations and with there units.
Value of the following measurements are given as follows:
MASS 1kg
LENGTH 1m
TIME 1s
FORCE 1N
STRESS 1Pa
ENERGY 1Nm
DENSITY 1Kg/m3
YOUNG'S Modulus 210GPa
Velocity 56.33KMPH
GRAVITY 9.8m/s2
Now, here are a few system of units:
Kg cm ms
Kg cm s
gm mm ms
kg m s
g cm s
g cm us
g mm s
ton mm s
slug ft s
kg mm s
g cm ms
kg mm ms
DIFFERENT TYPES SYSTEMS
- CGS SYSTEM
- FPS SYSTEM
- MKS SYSTEM
PROCEDURE
As per the requirement explained below with detail calculation for conversion from SI unit to gm/mm/ms.
SI unit for gm mm ms
Mass 1 Kg = 1000gm
Length 1 m = 1000mm
Time 1 s = 1000 ms
Force 1 N = (1Kg*m)/s^2
(1000gm*1000mm)/(1000ms*1000ms)
( 1 gm * mm)/ms^2
Stress 1pa = N/m^2 = [(1gm *mm/ms^2]/(1000ms*1000ms)
= 10^-6gm/,,*ms^2.
Energy 1 Nm = [(1kg*m/s^2]*(1000mm)
= 10^3gm*mm^2/ms^2
DENSITY 1Kg/m3 = 1000gm/(10^3 ms)^3
= 10^3 gm/10^9 ms^3
= 10^-6 gm/ms^3
Youngs's Modulus 210Gpa { 1Gpa = 10^9 × (N/m^2)}
210 Gpa = 210 × [10^9 ×(N/m^2)]
= 210[10^9 × (10^-6gm/mm*ms^2)]
= 210 × 10^3 gm/mm*ms^2
= 210000 gm/mm*ms^2.
Velocity [1Km = 10^6mm]
1KMPH = 10^6mm/(3600*1000ms) [1HR = 3600*1000ms]
10/36 = 0.277mm/ms
56.33 KMPH = 56.33×0.277
= 15.64 mm/ms
GRAVITY 9.8m/s2
1m/s2 = 1000mm/ (1000ms × 1000ms )
= 10-3 mm/ms^2
9.8 m/s2 = 9.8 × 10^-3 mm/ms^2.
Rest unit conersion in attached in below image
