Download Introduction - UT Mechanical Engineering

M.D. Bryant
ME 344 notes
Introduction
9/8/05
1
Major course topics
Physics review & bond graphs
review systems
electrical
mechanical translational
mechanical rotational
fluidic
bond graphs
powerful modeling techniques
abstraction of "equivalent circuit"
intuitive
power/energy flows (replaces vector mechanics)
kinematics
Modeling & Simulation
State equations & solution
Control
Design techniques & applications
M.D. Bryant
ME 344 notes
Introduction
9/8/05
2
Bond Graph Concepts: Power Flow in Physical Systems
power input:
sources and / or
upstream components
power output:
downstream
components
energy storage
power losses
*
physical system ( electrical, mechanical, electro-mechanical, etc. )
*
power in: Pin
*
power stored in system as:
potential energy (energy of position)
kinetic energy (energy of motion)
*
losses via dissipation: Ploss ⇒
*
power out: Pout
resistance
⇒
⇒
capacitance
inertance
M.D. Bryant
ME 344 notes
Introduction
Map of Power Flows
Power balance
Pin - Pout - Pstored - Ploss = 0
9/8/05
3
M.D. Bryant
ME 344 notes
Introduction
9/8/05
4
Power
electrical:
P=Vi
[ Watts ]
V: potential difference (voltage) [ Volts ]
i: current [ Amperes ]
mechanical translational:
P=Fv
[ Watts ]
F: force [ Newtons ]
v: linear velocity [ meters/sec. ]
mechanical rotational:
P=Tω
[ Watts ]
T: torque [ Newton meters ]
ω: rotational velocity [radians/sec. ]
magnetic:
P=M
"˙
[ Watts ]
M: magnetomotive force [ Amp ],
"˙ : magnetic flux rate [ Webers/sec. = Volt]
!
hydraulic:
!
P=pu
[ Watts ]
p: pressure [ Pascals = N/m2 ]
u: volumetric flow rate[ m3 /sec. ]
thermal:
P = T S˙
[ Watts ]
T: temperature [ °K ]
S˙ : entropy flow rate[ watts/°K. ]
GENERALIZE:
e: effort
f: flow
P=ef
[ Watts ]
M.D. Bryant
ME 344 notes
Word Bond Graphs
9/8/05
WORD BOND GRAPHS
•

Maps where power flows, energy stored
Represents elements with blocks
Tra nsm iss ion
River inflow
Reservoir
Li nes
Electrical
Transformer
Generator
Dam
Electrical
Transformer
User Residenc e
Turbine
To other transm issi on
l ines a nd houses
Sluice
River outflow
Example: hydroelectric power plant
• Power Source: sun (evaporates water)
• Rain in river-basin
• Water collects in reservoir (energy stored in
“tank”)
• Sluice guides flow across water turbine
• Turbine propels generator
• Electric power transmitted to users
environment
sun
&
rain
rotational
hydraulic
river
flow
dam
storage
electrical
sluice
inertia
turbine
inertia
generator
inertia
transformer
inductance
wire
inductance
transformer
inductance
user
sluice
flow
water
turbine
generator
transformer
transmission
line
transformer
power
distribution
sluice
losses
turbine
losses
generator
losses
transform
losses
transmit
losses
transform
losses
user