Page 2 - Combined_52_OCR

ISOLATION

ISOLATORS
high, standing waves tend to occur in SA V PoPon
lation based upon a massless resilient AIR SA TO
insmissibility may become relatively
ult to determine by analytical means ___
■rporate irregularly shaped metal or __ PRESSURE
onstrated by a simplified model. *
)d by a linear unidirectional isolator </> "I
.missibility can be written in terms of p S /l S 7^7 f ____________
equivalence of velocity and displace- AT CONSTANT VOLUME

*0 ... Zbl2 SKETCHES; RELEVANT PROPERTIES OF THE RESILIENT MATERIAL ARE: . 4
(30.91) Undamped r
uo Ze 4- Z™ I M A HEAT CONSTANT
•>fer impedance of the isolator with Gd 4 8ND 3 7r2/>NDd2 4 80 DENSITY, LB -S E C 2/IN TE R IA L, IN.3
is the point impedance of the iso- in AT
h station 1 blocked, and is the SPECIFIC
; equipment at terminal 2. Assum- Effects HEAT
one-dimensional mechanical trans- . V = VOLUME OF R ESILIEN T
•ed impedances are 16>23 OF P = PRESSURE, LB /IN .2
W ave 1 __________________ SPECIFIC
c SHEAR </> SsG 1 pS si p = MASS = RATIO
to
(30.92) n
^)=Zccoth7/
smh yl/ Relating
impedance Zc is GIp 1 7rpD 2l T “

— -j(co2p)J (30.93) in d ic a t e d IN
w Parameters
e isolator cross section area under-
erial of the isolator * and cq is the
Characteristic _
1 for the resilient material of the CONDITIONS)
ger than the lateral dimension of COMPRESSION Sc SHEAR, L B /IN .2
(30.94) :_ 1 1____________. ELEM ENTS ARE IN
g in the material) and the phase 3. R E S ILIE N T
(uations of motion that apply for Kstml
nd 3 are defined by 26 30. g e n e r a l S MODULUS, L B /IN .2 OF E LA S TIC ITY MODULUS, L B /IN .2 IN IT IA L INDICATES
Table 0 F SYSTEMS OF THE
(30.95) d ia g r a m s Z c 0
Eq. (30.92) are substituted into ISOLATION OF CHARACTERISTIC
he following result is obtained: PROPERTY CROSS-SECTION AREA STATIC STIFFNESS MASS RESILIENT a t e r ia l e l a s t ic WAVE p r o p a g a t io n VELOCITY c0 IMPEDANCE _________ DIM ENSIO NS E= YOUNG'S 6 = MODULUS k (SUBSCRIPT =B U LK
— (30.96) m

amping coefficient having a value
3 resilient material of the isolator. 30-53