This is the third leading paper of a large cycle devoted to our new method to obtain the exact analytical solutions for vibrant elastic lumped and distributed systems. Its initial version was published in "Materials. Technologies. Tools", the journal of National Academy of Sciences of Belarus, 5 (2000), 3, pp.14-19 (in Russian). In the present version we retained generally the original part of the published paper, so the English-language readers can consider it as the elaborated version of the published paper. We have essentially widen the analysis of conventional methods; in our view, it presents more brightly the advantages which our method adds to the calculation scope and which we embody in our investigations, both published and being about publishing in the nearest future. 
You can find this and other papers of this cycle in our electronic journal SELF Transactions (for free) at http://angelfire.lycos.com/la3/selftrans  , as well as many other interesting results, both there and on our web site at http://angelfire.lycos.com/la3/SELFlab  .  We will be very grateful if you visit it and express us your opinion of our results or your interest to join us in our research.