The damping data is written to or read from a file as
the number of items which is 3 for mu, Nfb, omega;
the number of plies;
the array of mu values, one for each ply;
the array of Nfb values, one for each ply;
and
the array of omega values, one for each ply.
The data is split into as many lines as required,
each line beginning with "DAMPING"
containing a maximum of 5 array values per line.
For the Damping values:
| Ply | mu - Coefficient of friction | Nfb - Number of broken fibers | omega - Forcing angular velocity |
|---|---|---|---|
| 6 | 0.6 | 100.0 | 6.0 |
| 5 | 0.5 | 200.0 | 5.0 |
| ... | ... | ... | ... |
| 1 | 0.1 | 600.0 | 1.0 |
DAMPING ; 3; 6; 0.1; 0.2; 0.3; 0.4; 0.5; DAMPING ; 0.6; 600.0; 500.0; 400.0; 300.0; DAMPING ; 200.0; 100.0; 1.0; 2.0; 3.0; DAMPING ; 4.0; 5.0; 6.0;
If the Graphical User Interface (GUI) is used, the appropriate values are entered using the keyboard. Additional capability is invoked by clicking with the mouse on any of the buttons at the bottom of the window. There is a non-functioning prototype for setting the Damping Input data.
The significance of material damping to the dynamic performance of structures is broadly recognized. Passive damping has been proved to be a significant design parameter for vibration control, fatigue endurance, and impact resistance. It is well known that fiber/polymer-matrix composites may provide one or two orders of magnitude higher material damping than common metals, in addition to other superior elastic properties, such as high specific moduli and specific strength. An additional appealing design factor is the possibility to tailor the composite damping, together with other mechanical properties, by controlling the anisotropy of the composite material. This combination of high damping and advanced mechanical characteristics makes fiber/polymer-matrix composite materials ideal to a range of high-performance light-weight structures where passive vibration control is critical, such as space and aerospace structures, engine blades, high-speed mechanisms, etc.
An integrated micromechanics methodology for prediction of damping capacity in fiber-reinforced polymer matrix unidirectional composites has been developed. Explicit micromechanics equations based on hysteretic damping are presented relating the on-axis damping capacities to the fiber and matrix properties and volume fraction. The damping capacities of unidirectional composites subjected to off-axis loading are synthesized from on-axis damping values. Predicted values correlate satisfactorily with experimental measurements. The hygro-thermal effect on the damping performance of unidirectional composites due to temperature and moisture variations is also modeled. The damping contributions from interfacial friction between broken fibers and matrix are incorporated. Finally the temperature rise in continuously vibrating composite plies is estimated.