- Consistency of Units
INTRODUCTION
Different industries use different system of units as per their convenience. The units for the basic measurement quantities, mass distance and time - dictate how the other derived quantities will be expressed. For example, automotive industries use kg,mm,ms as their standard unit system. Construction industries are likely to use tonne,m,s as their unit system. Similarly, PCB simulation in electronic industry uses gm, micrometer,ms as their system of units.
LS-DYNA doesn't have a default system of units. User needs to input material properties and physical dimensions according to a consistent system of units as per their 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.
Here's an example: Young's Modulus of steel is 210GPa which is input as 210e+9 in LS-DYNA as per SI unit system. However, if you use kg/mm/ms unit system, the input quantity will be 210. Thus the conversion factor is 10^-9.
But, how?
That's for you to find out in this assignment.
OBJECTIVE
Providing the conversion factors of different units and converting them successfully.
LS Dyna has got different types of unit system, but user needs to be able to input all dimensions with consistency.
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
PROCEDURE
This report is going to show direct calculation procedure for converting any measurement to a consistent SI-Unit. The first example would be for converting,
SI-UNIT to gm/mm/ms
MASS 1kg = 1000gm
LENGTH 1m = 1000mm
TIME 1s = 1000ms
FORCE 1N = [kg*m]/s2
(1000gm*1000mm)/(1000ms*1000ms)
(1gm*mm)/ms2
Factor= 1
ENERGY = 1Nm = ([kg*m]/s2)) *1000mm
1000gm*mm2/ms2
Factor= 10^3
DENSITY = 1kg/m3 = 1000gm/(1000*1000*1000)mm
= 10^6gm/mm^3
Factor= 10^-6
MORE UNIT SYSTEMS
CONCLUSION
This report has successfully illustrated some base measurements and their accurate unit conversions together with their conversion factors.