Testing Procedure
www.ndtjames.com 29
Mu= E/(2G)
– 1 (ii)
(E): Dynamic Young’s Modulus of elasticity (obtained according eq.
(i))
(G): Dynamic modulus of rigidity (input by the user, the
recommended value of (G) is the obtained in a previous Torsional
test).
Transverse Frequency Mode
In order to obtain the elastic constant of the specimen in the
transverse or flexural mode, the user should input some data. By
placing the cursor on the first line and pressing the enter key the
user can input the desire value of Dynamic Modulus of Rigidity (G)
that is going to be used for the computations. The user should also
input a Dynamic Poisson’s ratio (µ) value, otherwise the default
value would be (µ= 0.17).
The system will calculate the dynamic Young’s Modulus of elasticity
according to e.q. (iii), using obtained and computed parameters:
M= mass of the specimen (kg)
n= fundamental transverse frequency (Hz.)
t, b= dimensions of cross section of prism (m), t being in the
direction in which it is driven (distinguish between t and b is
important for transverse frequency).
C= 1.6067 (L³T/d^4), Ns² /(kg m²) for a cylinder or
C= 0.9464 (L³T/bt³), Ns² /(kg m²) for a prism
K= d/4 (m) for cylinder or
K= t/3.464 (m) for prism
T is obtained according to Table 4, using (K/L) and (µ).
E = D M n² (iii)
At the fundamental transverse resonant frequency there are two
nodal points, at distances from each end of 0.224 times the length.
Position the supports for transverse vibration 0.224 times the
specimen length from the ends as shown in Fig. 23. Place the hard
rubber circular rods in the grooves of the supports.
