Investigatio n of anomal y - Analy tical stud y 

The refle ctors depl oy due  to the spring  torque s at the hinge a ssemblies of the  deployment mech anism.  On latch -up, the kineti c energy of the deploying a ppend age results in  a forward sh ock followed by a  reverse  shock at the l ocking linkage – outboard bracket pai r. While  the latch-up perform ance was nomi nal  for East reflector, the West refle ctor showed 3 rebound s before final latchin g. Once the roller of th e  locking lin kage enters the slot at the en d of deploym ent, the confi gurat ion sho uld resist the forwa rd and  reverse shocks without instability. In the case of West  reflector the reverse shock was disl odging the roller  from the slot and the roller was ridi ng over the outb oard bracket sector till the motion come s to re st an d  subsequently due to  the spring to rque the motio n was initiated  in the fo rward direction.  This a ction  repeated a co uple of times before the fin al locking.  

In order to a nalyze th e rebouncing behavior of th e hinge me chanism for th e reverse shock loads, studi es  were carried out by a pplying static m oments i n the reverse  (stowing) direction  for both  the reflector hin ge  config uratio ns. The an alytical stu dies were carried out with the following ass umptions :  - Frictio n torques at the  interfaces h as been  neglected. As the presen ce of friction opposes the  motion the re sults o btaine d by negle cting the sam e will be on the conservative side.  - The stru ctural  stiffness of the b rackets are assumed to be high  and all the  move ments analy zed are  due to the kin ematics of the mech anism only and t he stru ctural defl ection s are n ot con sidered.   - A combin ed radial cl earan ce of 0.05 m m is assu med to be pre sent betwee n the rolle r- pin - slot. 

The sche matic co nfiguratio n of the outboard b racket and lockin g linka ge asse mbly for the East and We st  reflectors are as shown i n Figure 3a and Figure 3b. Under equilibrium conditions due to the action of the  spring to rques on the outb oard bracket and th e locking lin kage th e poi nt of contact of the  roller in the slot  is at point ‘ A  ‘. Wh en an external to rque (T) is applied in th e reverse (stowing) direction th e roll er move s  in the sl ot an d the po sition  of equilib rium change s depen ding on the mag nitude  of the appli ed torq ue. The   relation b etween the appl ied torqu e and the angul ar moveme nt of the outboard b racket (θ) can be   comp uted based on the equation s of equilibri um fo r the l ocking linkage and the out -board bracket. The   derived  equations fo r West reflecto r are as follo ws for a hinge line spring to rque (TS) of 0.863Nm  and  locking linkage spri ng torque (T L)  of 1.32 4Nm: 

() ()()αα αCosCos SinT ×    −×− =02.0 093.0122.0 324.1863.0    &       () ()    − × ×− +=− ααθ 90 05.0 1222 05.0 12205.0 2 21 CosCosSin  

Nomenc lature:    P = Rea ction on the rolle r under e quilib rium con dition.    α = Angle su btende d by re action P with horizontal.   C = Extreme point on semi circula r slot in forwa rd direction.   B = Extreme point on semi circula r slot in reverse direction. 

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