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CHAPTER 13 - RIGIDS

CHAPTER 13 - RIGIDS. CONTENTS. Rigid Body Definition Rigid Surfaces Rigid Material Rigid Body Loading Rigid Bodies Constraints. RIGID BODY DEFINITION. In MSC.Dytran arbitrary rigid bodies can be defined by: • Arbitrary shaped rigid surfaces • Rigid material • Rigid Body Element.

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CHAPTER 13 - RIGIDS

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  1. CHAPTER 13 - RIGIDS

  2. CONTENTS • Rigid Body Definition • Rigid Surfaces • Rigid Material • Rigid Body Loading • Rigid Bodies Constraints

  3. RIGID BODY DEFINITION • In MSC.Dytran arbitrary rigid bodies can be defined by: • • Arbitrary shaped rigid surfaces • • Rigid material • • Rigid Body Element

  4. SURFACE, 333,, PROP, 111 • SET1, 111, 222 • RIGID, 25, 333, 200.,, 1., 1., 1.,, + • +,,,, 100.,,,,, + • +,,1E5,1.E5,1.E5,1.E5,1E5,1E5 RIGID SURFACE - RIGID • Rigid surface geometry defined by a arbitrary shaped multi-faceted surface • Rigid surface properties must be defined by the user • - center of gravity • - mass • - moments of inertia • Rigid surface initial velocity can be defined • Example: Rigid 25 which geometry is defined by surface 333, has a mass of 200 kg, center of gravity is at (1., 1., 1.) and has moments of inertia of 1.e5 Initially the rigid surface has a velocity of 100 m/s in z- direction.

  5. RIGID MATERIAL - MATRIG • • Material treated as one rigid element • No matter how many elements and properties are used to make up the rigid body, in the solution it is treated as a single element They are very cheap to use • Name will become: MR<material number> • • MATRIG properties can be defined by the user • Normally, the user would simply replace a material entry like DMATEP by MATRIG, after which MSC.Dytran calculates the geometric properties of the rigid body from the density or mass and geometry • The user can also supply center of gravity, mass, moments of inertia and initial velocities himself

  6. RIGID MATERIAL - MATRIG(Continued) • Example: Rigid material number 19 which properties like mass, center of gravity and moments of inertia are calculated by MSC.Dytran • MATRIG, 19, 7850. • Name will become: MR19 • Example: Rigid material number 200 with initial velocity of 10 in x-direction and of which the mass is 1000., center of gravity is at (0., 7., -3.1) and also the moments of inertia are supplied by the user • MATRIG, 200, , 210.E9, 0.3, 1000., 0.0, 7.0, -3.1, + • + , 17.0, 13.2, 14.3, 0., 0., 10., , , + • + , 10., 0., 0., 0., 0., 0. • Name will become: MR200

  7. RIGID BODY ELEMENT - RBE2-FULLRIG • Defines a set of grid points that form a rigid body • This entry allows particular degrees of freedom of a set of grid points to be tied together so that they always move the same amount • Properties of rigid body will be calculated by MSC.Dytran based upon the masses associated with the grid points that are part of the RBE2-FULLRIG • Name will become: FR<material number> • Example: Nodes 1 to 28 and 55 will behave like a rigid body • RBE,12,55,FULLRIG,1,THRU,28 • The name will be FR12

  8. Prescribes transient dynamic loadingTYPE = 13 in TLOAD1 definitionMust be selected in Case ControlAny loading (TLOADn entry) not selected in Case Control is ignoredLoading acts on the center of gravity of the rigid body RIGID BODY LOADING

  9. RIGID BODY LOADING(Continued) • Example: Force on rigid material 19 varying in time • TLOAD = 1 • BEGIN BULK • ... • MATRIG, 19, 7850. • TLOAD1, 1, 444, , 13, 12 • FORCE, 444, MR19,, 100., 0., 0., 1. • TABLED1, 12, , , , , , , , + • +, 0.0, 0.0, 1.0, 1.0, ENDT • Example: Force on rigid surface 19 • TLOAD = 1 • BEGIN BULK • ... • RIGID, 19, 333, 200.,, 1., 1., 1.,, + • +,,,, 100.,,,,, + • +,,1E5,1.E5,1.E5,1.E5,1E5,1E5 • TLOAD1, 1, 444, , 13 • FORCE, 444, 19,, 100., 0., 0., 1.

  10. RIGID BODY LOADING(Continued) Example: Force and moment on a FULLRIG-RBE2 19 TLOAD = 1 BEGIN BULK ... RBE,19,55,FULLRIG,1,THRU,28 TLOAD1, 1, 444, , 13 FORCE, 444, FR19,, 100., 0., 0., 1. MOMENT, 444, FR19,, 100., -1., 0., 0.

  11. Prescribes transient dynamic velocity fieldTYPE = 12 in TLOAD1 definitionMust be selected in Case ControlAny loading (TLOADn entry) not selected in Case Control is ignoredThe center of gravity of the rigid body will be constraint RIGID BODY CONSTRAINTS

  12. Example: Z-velocity of a rigid material 19 varying in time Allow body to move freely in x and y-direction TLOAD = 1 BEGIN BULK ... MATRIG, 19, 7850. TLOAD1, 1, 444, , 12, 13 FORCE, 444, MR19, ,100., , , 1. TABLED1, 12, , , , , , , , + +, 0.0, 0.0, 1.0, 1.0, ENDT Blanks!!! RIGID BODY CONSTRAINTS(Continued)

  13. RIGID BODY CONSTRAINTS(Continued) Example: Constrain rigid body MR19 to move in any direction TLOAD = 1 BEGIN BULK ... MATRIG, 19, 7850. TLOAD1, 1, 54, , 12 FORCE, 54, MR19, , 0., 1., 1., 1. MOMENT, 54, MR19, , 0., 1., 1., 1.

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