TY - JOUR
TI - Joined statistical – thermodynamic expression for entropy and Hook’s law in the analysis of states of elongated ligament biostructure
AU - Stanković Milan
AU - Janjić Nataša
AU - Ninković Srđan
AU - Harhaji Vladimir
AU - Savić Dragan
AU - Milankov Miroslav
JN - Thermal Science
PY - 2016
VL - 20
IS - 12
SP - 573
EP - 580
PT - Article
AB - Analytic joined statistical - thermodynamic expression for entropy as a  function of state for measuring disorder of the corresponding micro state and  the mechanical parameters which feature in Hooke’s law on elasticity as a  measure of macro state was used in the situation of isothermal elongation of  viscoelastic ligament biostructure simultaneously with external force of  constant intensity to determine the change of entropy and the resultant  reactive elastic force in the function of relative elongation. The sample  used for the analysis and testing of the original joined theory shown with  adequate equations is tested on linear biostructure approximating the data of  Lig. collatelare fibulare which strengthens the lateral side of the knee  joint. The obtained results for the tested linear biostructure according to  which the minimal value of the difference in dS corresponds to the state of  maximal entropy and the minimal value of elastic force indicates the  acceptable level of elongation at which a reversible process is still  possible, with low probability. This leads to the conclusion that, according  to the results obtained here, the biostructure under examination can  withstand the elongation which is approximately equal to twice the initial  length L0. The relation between the friction force Ftr and the elasticity  force Fe for the initial state is 1.0417, which indicates that the friction  force is to a certain extent higher than the elastic force. With elongation  this ratio changes in favour of the friction force and becomes more prominent  with advanced age.