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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
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