force modify direct single_component_force

For translational action-reaction forces, Adams applies the user-defined force along the line connecting the I and the J markers. The force exerted on I is directed from J toward I, while the force exerted on J is directed from I toward J.

For translational action-only forces, Adams applies the force on the I marker only. There is no reaction on the J marker. The force on the I marker is directed along the z axis of the J marker.

For rotational action-reaction forces, Adams applies the torque on the I marker about the z axes of the J marker. Furthermore, Adams assumes that the z axes of the I and the J markers are constrained to always be parallel for this type of single-component force.

For rotational action-only forces, Adams applies the torque on the I marker only. There is no reaction on the J marker. The torque on the I marker is directed along the z axis of the J marker.

You write a FUNCTION expression or a user-written subroutine (an SFOSUB) to define the constitutive equation for the force applied at the I marker. Adams evaluates the reaction forces at the J marker.

If the single-component force is not visible on the screen, you must type the name. You may also find it convenient to type the name even if the single-component force is displayed.

If you created the single-component force by reading an Adams data set or graphics file, the single-component force name is the letters SFO followed by the Adams data set single-component force ID number. The name of Adams SFORCE/101 is SFO101, for example. If you created the single-component force during preprocessing, you gave it a name at that time.

If a single-component force is available by default, you may identify it by entering its name only. If it is not, you must enter its full name. To identify a single-component force under another model, for instance, you may need to enter the model name as well. For example, you may specify single-component force 'spring' from the model 'suspension' by entering ".suspension.spring". If you type a "?", Adams View will list the single-component forces available by default.

You must separate multiple single-component force names by commas.

If the single-component force 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 single-component force picks by commas.

Normally, entity names are composed of alphabetic, numeric, or '_' (underscore) characters, and start with an alphabetic or '_' character. They may be 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 over ride 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, or course, delete this name and use your own. The form of a full name is:

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.

The easiest way to enter a function expression in Adams View is to use the text editor in combination with the function builder. To invoke the text editor for entering a function expression, highlight the function field and then either pick the "EDIT" button at the top of the panel or type a ^t (control-t). The Adams View "function builder" is discussed below.

The syntactical correctness of a function expression can be investigated by using the "VERIFY" button at the upper right 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:

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 of 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 access 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 ge 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.

A FUNCTION expression with an arithmetic IF and its four expressions is 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 ge 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 be a list of functions that can be accessed.