Wave speed as a function of compression?

[PhysicsMike]

Dear physics forum, I am doing an experiment on the vibrational behavior of beams and a question has come up that I can't answer. How does compression affect wave speed?

Brief overview of the experiment:

studying the change in vibrational behavior of a beam that is gradually tapered toward a point (equilateral triangle). Basically I have four beams:
Beam 1: uniform rectangle
Beam 2: tapering begins
Beam 3: more tapering
Beam 4: beam comes to a point at one end.

The beams are clamped at one end, with the other end open. If you take the ground to be the 'x-axis', then the length of the beam is in the 'x-axis', the width in the 'z-axis', and the height in the 'y-axis'. Aka the beam, which is quite flexible (synthetic trim board), does not sag due to gravity.
Their is a sin-wave generator located 100mm from the clamped end. I've found that even when i hang the beam, or stand it up (clamp closest to ground), the node placement does not change. What i have found, is that the wavelength decreases the farther i get from the clamped end, aka the wave speed is decreasing.
basically I've got compression on the bottom and tension on the top of the beam. I know v=sqrt(T/u), but does anyone have any insight into wave speed as a function of compression?

any insight is welcome, thanks

 

[gomunkul51]

Is the beam made out off two parts of which one is under tension and the other under compression? Or what is being compressed by what?Roman.

 

[Khashishi]

If you are talking about sound waves, the speed of sound depends on the bulk modulus. See https://en.wikipedia.org/wiki/Speed_of_sound
I suppose if most materials are compressed, the bulk modulus will increase, so the sound speed should increase.

 

[Khashishi]

If you are talking about sound waves, the speed of sound depends on the bulk modulus. See https://en.wikipedia.org/wiki/Speed_of_sound
I suppose if most materials are compressed, the bulk modulus will increase, so the sound speed should increase.