force create direct multi_point_force

2. Formulation The MULTI_POINT_FORCE creates a set of forces and torques, which act between the I and J markers, which appear in the MULTI_POINT_FORCE. These forces and torques are linear functions of the relative displacements and velocities of the markers, in a manner equivalent to the finite element method. For each MULTI_POINT_FORCE, one marker (J) is used as the reference marker. The velocities are resolved into the J markers reference frame and expressed in the J markers coordinate system. The force and torque components computed by the MULTI_POINT_FORCE are also given in the J markers coordinate system. The force-displacement and force-velocity relationships are specified using stiffness and damping matrices, or by using a stiffness matrix and a proportional damping ratio. These matrices are defined using MATRIX statements in the data set. The stiffness and damping matrices that Adams requires are defined for the I markers only, i.e. they should be derived normally using the (6n+1) J marker and I marker degrees-of-freedom, but are input using only the rows and columns corresponding to the I marker degrees-of-freedom. This is equivalent, in finite element terminology, to applying fixed boundary conditions at the J marker by simply removing the corresponding rows and columns from the matrices. Adams will automatically compute and apply the correct reaction forces at the J marker based on the I markers responses.

3. Normally, entity names are composed of alphabetic, numeric, or '_' (underscore) characters, and start with an alphabetic or '_' character. For more information, see Using Extended Names. They may be of any length. By enclosing the name in double quotes, you may use other printable characters, or start the name with a numeral. If a name contains characters, or starts with a numeral, you must always quote the name when entering it. Note that you can specify the parentage of an entity (e.g. what part "owns" a marker or a geometry element) when you CREATE it by changing the name. If you enter just the entity name, then the default parent will be assigned by Adams View. If you type in the full name, then you may override the default parent. In most cases, when creating an entity, Adams View will provide a default name. The default name that Adams View provides will specify the parentage that it has assumed. You may, of course, delete this name and use your own.

4. When you use the FILE Adams_DATA_SET WRITE command, Adams View writes an Adams data file for your model. Adams requires that each modeling element be identified by a unique integer identifier. If you use this parameter to specify a non-zero identifier, Adams View will use it in the corresponding statement in the Adams data file. You may also enter zero as an identifier, either explicitly or by default. The next time you write an Adams file, Adams View will replace the zero with a unique, internally generated identifier. Adams View will permanently store this identifier with the element just as if you had entered it yourself. Normally, you would let all identifiers default to zero, and Adams View would generate the identifiers for you. You are never required to enter a non-zero identifier. You only need to specify it if, for some reason, you wish to control the Adams file output.

5. When an Adams Solver data file (.adm) is read into Adams View, all comments associated with a statement (from the end of the previous statement through the end of the current statement) are stored with the object. Comments in the data file can be associated with model. These comments must follow the title statement and be followed by the comment 'END OF MODEL COMMENTS'. This string must be uppercase. When an Adams Solver data file is written, the comments for an object are written before the statement corresponding to the object.

6. The i_marker_name specifies a marker on the first of two parts connected by this force element. Adams View connects this element to one part at the I marker and to the other at the J marker.

7. The j_marker_name specifies a marker on the second of two parts connected by this force element. Adams View connects this element to one part at the I marker and to the other at the J marker.

8. This stiffness matrix is a 6n x 6n matrix (n is the number of I markers) that defines the linear relationships between the I marker displacements relative to the J marker and elastic forces generated by the multi_point_force. The stiffness matrix is derived in the J markers coordinate system. Marker translational and rotational displacements appear sequentially in DX-DY-DZ-AX-AY-AZ order, while the markers appear in the same sequence as in the i_marker_name parameter. You may identify a matrix by typing its name or by picking it from the screen. Since a matrix does not have a geometric position, Adams View displays matrix icons at or near the model origin. If the matrix icon is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the matrix icon is displayed. If you created the matrix by reading an Adams data set or graphics file, the matrix name is the letters MAT followed by the Adams data set matrix ID number. For example, the name of Adams MATRIX/101 is MAT101. If you created the matrix during preprocessing, you will have given it a name at that time. If a matrix is owned by the default model, you may identify it by entering only its name. If it is not, you must enter its full name. To identify a matrix under a different model, for instance, you may need to enter the model name as well. For example, you may specify matrix 'control_points' from model 'road_surface' by entering ".road_surface.control_points'". If you type a "?", Adams View will list the matrix available by default. You must separate multiple matrix names by commas. If the matrix is visible in one of your views, you may identify it by picking on any of the graphics associated with it. You need not separate multiple matrix picks by commas.

9. The damping matrix is a 6n x 6n matrix (n is the number of I markers) that defines the linear relationships between the I marker velocities relative to the J marker and the viscous forces generated by the multi_point_force. The damping matrix is derived in the J markers coordinate system. If neither damping matrix nor the damping ratio is given, the multi_point_force will be undamped. Marker translational and rotational velocities appear sequentially in VX-VY-VZ-WX-WY-WZ order, while the markers appear in the same sequence as in the i_marker_name parameter. You may identify a matrix by typing its name or by picking it from the screen. Since a matrix does not have a geometric position, Adams View displays matrix icons at or near the model origin. If the matrix icon is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the matrix icon is displayed. If you created the matrix by reading an Adams data set or graphics file, the matrix name is the letters MAT followed by the Adams data set matrix ID number. For example, the name of Adams MATRIX/101 is MAT101. If you created the matrix during preprocessing, you will have given it a name at that time. If a matrix is owned by the default model, you may identify it by entering only its name. If it is not, you must enter its full name. To identify a matrix under a different model, for instance, you may need to enter the model name as well. For example, you may specify matrix 'control_points' from model 'road_surface' by entering ".road_surface.control_points'". If you type a "?", Adams View will list the matrix available by default. You must separate multiple matrix names by commas. If the matrix is visible in one of your views, you may identify it by picking on any of the graphics associated with it. You need not separate multiple matrix picks by commas.

10.   The elements of the damping matrix are determined by multiplying the corresponding stiffness matrix element value by this number. If direct input of the damping properties is desired, the DAMPING_MATRIX_NAME parameter may be used. If neither DAMPING_MATRIX_NAME nor DAMPING_RATIO is given, the MULTI_POINT_FORCE will be undamped. The user must specify a STIFFNESS_MATRIX_NAME with the DAMPING_RATIO parameter.

11.  The length matrix is a 3n x 1 matrix (n is the number of I markers) of translational displacements only, in DX-DY-DZ order. Usually, the length matrix will be used to specify the system's free (no internal force) lengths when they differ from the input positions. If the length matrix is not given, the multi_point_force assumes that the input positions of the I markers are at the reference locations. You may identify a matrix by typing its name or by picking it from the screen. Since a matrix does not have a geometric position, Adams View displays matrix icons at or near the model origin. If the matrix icon is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the matrix icon is displayed. If you created the matrix by reading an Adams data set or graphics file, the matrix name is the letters MAT followed by the Adams data set matrix ID number. For example, the name of Adams MATRIX/101 is MAT101. If you created the matrix during preprocessing, you will have given it a name at that time. If a matrix is owned by the default model, you may identify it by entering only its name. If it is not, you must enter its full name. To identify a matrix under a different model, for instance, you may need to enter the model name as well. For example, you may specify matrix 'control_points' from model 'road_surface' by entering ".road_surface.control_points'". If you type a "?", Adams View will list the matrix available by default. You must separate multiple matrix names by commas. If the matrix is visible in one of your views, you may identify it by picking on any of the graphics associated with it.

12.   The force_matrix is a 6n x 1 matrix (n is the number of I markers) of forces and torques, appearing sequentially for each marker in FXFY- FZ-TX-TY-TZ order, while the markers appear in the same sequence as in the I_MARKER_NAME parameter. The force and torque components are expressed in the coordinate system of the J marker. When the LENGTH_MATRIX_NAME will be used to specify the system's free lengths, the FORCE_MATRIX_NAME gives the matrix of external preloads. If the FORCE_MATRIX_NAME is not given, the multi_point_force acts as though a matrix of zeros were input. You may identify a matrix by typing its name or by picking it from the screen. Since a matrix does not have a geometric position, Adams View displays matrix icons at or near the model origin. If the matrix icon is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the matrix icon is displayed. If you created the matrix by reading an Adams data set or graphics file, the matrix name is the letters MAT followed by the Adams data set matrix ID number. For example, the name of Adams MATRIX/101 is MAT101. If you created the matrix during preprocessing, you will have given it a name at that time. If a matrix is owned by the default model, you may identify it by entering only its name. If it is not, you must enter its full name. To identify a matrix under a different model, for instance, you may need to enter the model name as well. For example, you may specify matrix 'control_points' from model 'road_surface' by entering ".road_surface.control_points'". If you type a "?", Adams View will list the matrix available by default. You must separate multiple matrix names by commas. If the matrix is visible in one of your views, you may identify it by picking on any of the graphics associated with it.