Module MAPLEAF.Motion.forceMomentSystem

Classes

class ForceMomentSystem (force, location=None, moment=None)

Defines an applied force-moment pair at a location. Can be moved to other locations - recalculates the moment accordingly.

Expand source code

class ForceMomentSystem():
    '''
        Defines an applied force-moment pair at a location.
        Can be moved to other locations - recalculates the moment accordingly.
    '''
    __slots__ = [ "force", "location", "moment" ]

    def __init__(self, force, location=None, moment=None):
        self.force = force

        # Avoids using mutable default values
        if location == None:
            location = Vector(0,0,0)
        self.location = location

        # Avoids using mutable default values
        if moment == None:
            moment = Vector(0,0,0)
        self.moment = moment

    def __add__(self, force2):
        '''
            New force/moment system is calculated about self.location
        '''
        force2AtPresentLocation = force2.getAt(self.location)
        newForce = self.force + force2AtPresentLocation.force
        newMoment = self.moment + force2AtPresentLocation.moment
        return ForceMomentSystem(newForce, self.location, newMoment)

    def __neg__(self):
        return ForceMomentSystem(-self.force, self.location, -self.moment)

    def __sub__(self, force2):
        return self + (-force2)

    def getAt(self, newLocation):
        '''
            Returns a new force object, where the application location has been changed and the applied moment has been updated accordingly

            Moving the force/moment pair application to a new application location does not change the resulting applied force
            Only the applied moment changes to compensate for the force application location change
        '''
        # Find moment that the old force produces about the new location
        newToOld = self.location - newLocation
        momentAppliedAboutNewLocation = newToOld.crossProduct(self.force)
        # Add it to the previous moment
        return ForceMomentSystem(self.force, newLocation, self.moment + momentAppliedAboutNewLocation)

    def __str__(self):
        ''' Return string representation of object (Used by print()) '''
        return 'Force=({}) At=({}) + Moment=({})'.format(self.force, self.location, self.moment)

    def __eq__(self, force2):
        return self.force == force2.force and self.location == force2.location and self.moment == force2.moment

Instance variables

var force

Return an attribute of instance, which is of type owner.

var location

Return an attribute of instance, which is of type owner.

var moment

Return an attribute of instance, which is of type owner.

Methods

def getAt(self, newLocation)

Returns a new force object, where the application location has been changed and the applied moment has been updated accordingly

Moving the force/moment pair application to a new application location does not change the resulting applied force Only the applied moment changes to compensate for the force application location change

Expand source code

def getAt(self, newLocation):
    '''
        Returns a new force object, where the application location has been changed and the applied moment has been updated accordingly

        Moving the force/moment pair application to a new application location does not change the resulting applied force
        Only the applied moment changes to compensate for the force application location change
    '''
    # Find moment that the old force produces about the new location
    newToOld = self.location - newLocation
    momentAppliedAboutNewLocation = newToOld.crossProduct(self.force)
    # Add it to the previous moment
    return ForceMomentSystem(self.force, newLocation, self.moment + momentAppliedAboutNewLocation)