force create direct single_component_force

The syntactical correctness of a function expression can be investigated by using the "VERIFY" button at the upper right side of the text editor. If there is a syntax error, a message is printed and the cursor is put near the problem. Proper unit consistency is not checked during function expression verification.

The remainder of this explanation will cover the components of FUNCTION expressions as summarized in the following table:

FUNCTION expressions can include integers, real numbers, and exponents. In other words, any numbers that are legal in Adams are legal in a FUNCTION expression.

In a FUNCTION expression, Adams allows any of the operators **, *, /, +, and -. Adams executes these operators according to the following precedence rules:

Adams subtracts TIME from one before it performs multiplication and division.

You can include the following system constants in a FUNCTION expression:

The following example of a FUNCTION with a system constant multiplies the system constant PI by the displacement of marker 10 with respect to marker 14:

A FUNCTION expression can contain any number of blank spaces. Five consecutive blank spaces in an expression do not terminate input of the expression (by indicating that what follows is a comment) as they do in an Adams statement. However, you should remember these two restrictions.

You can use a comma to continue FUNCTION expressions. You can break the expression anywhere except in the middle of a number, in the middle of a name, or between a function and its left bracket. Put a continuation comma in column one of the following line before the rest of the expression. If you break the expression at a comma that is part of the expression, you must use both, the expression comma and the continuation comma. You may use more than one continuation comma to extend an expression over several lines.

The FUNCTIONS button at the right side of the Adams View text editor provides a means for constructing an Adams function string. These functions are briefly described below. Upon picking the FUNCTIONS button, you will be presented with the list of available functions in the "selection window". After you select the desired function, a panel will appear with fields representing the various parameters for the function. You will have full access to on-line help with this panel just like you have with regular panels. After you have completed the panel and selected the DONE button on the panel, the function string will be constructed and inserted at the current text cursor location in the text edit window.

A FUNCTION expression may access the current value of a system variable and use the value in computations. These values are accessed through a collection of functions. The accessible system variables include the following: Time, Mode, Displacements (Translational and Rotational), Velocities (Translational and Rotational), Accelerations (Translational and Rotational), Forces (Translational and Rotational), and User-defined variables. Invoke the text edit window and pick the FUNCTIONS button to get a list of functions that can be accessed.

In general, you use a function character string (such as DM, VX, or FZ) and a list of values (e.g. i1, i2, and i3) to access a system variable in an expression. For example, the value i1 may be the name of the marker for which you want to measure a quantity (such as displacement, velocity, acceleration, or force), i2 is the name of the marker with respect to which you want to measure the quantity, and i3 is the name of the marker you want to use to resolve the components of the quantity. If you do not specify marker i3, Adams computes the result in the ground reference frame.

Arithmetic IFs allow you to conditionally define FUNCTION. The format for arithmetic IFs follows.

Adams evaluates expression 1. If expression 1 is less than zero, the arithmetic IF equals expression 2; if expression 1 equals zero, the arithmetic IF equals expression 3; and if expression 1 is greater than zero, the arithmetic IF equals expression 4.

A FUNCTION expression with an arithmetic IF and its four expressions is as given below:

If the radial velocity between markers 10 and 31 is less than or equal to zero, the value of the FUNCTION expression is zero; but if the radial velocity between markers 10 and 31 is greater than zero, the value of the FUNCTION expression is six hundred.

In some ways, you may treat IF as a variable. For example, you can place it anywhere in the expression. In addition, you can nest arithmetic IFs nine levels deep.

You can use the FORTRAN functions ABS, ATAN, ATAN2, COS, EXP, LOG, LOG10, MIN, MAX, SIN, SQRT, and TAN in your expression. For more information about these functions, see a FORTRAN reference manual. Invoke the text edit window and pick the FUNCTIONS button to get a list of functions that can be accessed.

In general, an Adams function evaluates a mathematical equation and returns a value to your FUNCTION expression. The following table lists all the Adams functions and their purposes. Invoke the text edit window and pick the FUNCTIONS button to make a list of functions that can be accessed.

Normally, entity names are composed of alphabetic, numeric, or '_' (underscore) characters, and start with an alphabetic or '_' character. They may be of any length. For more information, see Using Extended Names.

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. The form of a full name is:

"...._NAME.GRAND_PARENT_NAME.PARENT_NAME.ENTITY_NAME"

The number of levels used varies from case to case and the parentage must exist before an entity can be assigned to it.

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.

When an Adams Solver data file is written, the comments for an object are written before the statement corresponding to the object.

By default, you supply Cartesian (x, y, z) coordinates. You may use the 'defaults units coordinate_system_type =' command to change this convention. For example, selecting 'cylindrical' means you will subsequently be supplying r, theta, and z coordinates.

Adams View applies your location coordinates in the coordinate system you identify with the RELATIVE_TO parameter. The default for the RELATIVE_TO parameter is the default coordinate system. (See the RELATIVE_TO parameter for this command).

By default, you supply Euler (body313, or body-fixed z, x, z) angles. You may change this convention with the 'DEFAULTS UNITS ORIENTATION_TYPE=' command. For example, selecting SPACE123 means you will subsequently be supplying space-fixed x, y, and z angles.

Adams View applies your orientation angles starting from the coordinate system you identify with the RELATIVE_TO parameter. The default for the RELATIVE_TO parameter is the default coordinate system.

Note that this does not completely dictate the orientation of the coordinate system. Adams View will position the coordinate system with an arbitrary rotation about the axis. If you must completely control the coordinate system orientation, use ORIENTATION or IN_PLANE_ORIENTATION.

By default, you direct the Z axis of the coordinate system. You may change this convention with the 'DEFAULTS ORIENT_AXIS_AND_PLANE AXIS_AND_PLANE_SETTING=' command. For example, selecting either X_AXIS_XY_PLANE or X_AXIS_XZ_PLANE means you will subsequently be directing the X axis. The plane-convention setting does not affect this parameter.

Adams View applies your location coordinates in the coordinate system you identify with the RELATIVE_TO parameter. The default for the RELATIVE_TO parameter is the default coordinate system.