航海仿真课件NavSim03-1.ppt

Simulation Technology John Shi Chaojian Formulating Equations from SchematicsCircuit Assign each node a voltage, with one node as 0 Formulating Equations from SchematicsCircuit Assign each element except current sources a current Formulating Equations from SchematicsCircuit Sum of currents = 0 (Kirchoff’s current law) Formulating Equations from SchematicsCircuit Equations to relate branch currents to node voltages Formulating Equations from chematics Structure Assign each joint an X,Y position, with one joint as zero. Formulating Equations from chematics Structure Assign each strut an X and Y force component. Formulating Equations from chematics Structure Strut Forces Formulating Equations from chematics Structure Sum of X-directed forces at a joint = 0 Sum of Y-directed forces at a joint = 0 Formulating Equations from chematics Structure Equations to relate strut forces to joint positions. Formulating Equations from chematics Heat Flow Formulating Equations from chematics Heat Flow Cut the bar into short sections Assign each cut a temperature Formulating Equations from chematics Heat Flow Heat Flow through one section Limit as the sections become vanishingly small Formulating Equations from chematics Heat Flow Formulating Equations from chematics Heat Flow Formulating Equations from chematics Heat Flow Temperature analogous to Voltage Heat Flow analogous to Current Formulating Equations from chematics Summary Two Types of Unknowns Circuit - Node voltages, element currents Struts - Joint positions, strut forces Conducting Bar – Temperature, section heat flows Two Types of Equations Conservation Law Equation Circuit - Sum of Currents at each node = 0 Struts - Sum of Forces at each joint = 0 Bar – Sum of heat flows into control volume = 0 Constitutive Equations Circuit – element current related to voltage Struts - strut force related to length change Bar – section temperature drop related to heat flow * * Merchant Marine College Shanghai Mar