located between them the structural member 2 has penetration holes 14 made in the distancing element 8 along its entire length said holes placed one after the other at specific intervals the holes 14 extend perpendicular to the axis 10 through the distancing element 8 as well as through the area of the covering 12 that encloses the distancing element 8 at the side the purpose of the holes 14 is to hold strings not shown of the webbing in the case of the structural member 2 being used to manufacture a tennis racquet frame fig1 a shows the functioning principle of the structural member according to the invention using the first embodiment in fig1 as an example in fig1 a two side views of the structural member in fig1 are shown without the covering if the structural member shown at the top in fig1 a is deflected or bent in the direction of arrow c tensile stresses occur in the upper resonating element 6 and compressive stresses occur in the lower resonating element 8 as a result of the coupling of the two resonating elements 4 6 by the distancing element 8 if the load imposed in the direction of arrow c is released the structural member oscillates from this deflected position backward and arrives at the state shown at the bottom of fig1 a in which resonating element 6 which was previously subjected to tensile stresses is compressed and resonating element 4 which was previously subjected to compressive stresses is stretched as the oscillation proceeds these states alternate back and forth the distancing element 8 functions as a neutral fiber such that it is essentially free of bending tension and compression stresses thus the.