Fig. 3 Variation of wnorm with jointe exibility parameter A Fj for a)root impulse and b ) tip impulse. disturbance structurally more critical than a control impulse of the same magnitude. Conclusions The present study has investigated the problem of the elastic response ofa genericspacevehiclewithdegradedjoints.Thesteppedbeamformulation basedonelementary beamtheoryisemployedfor extracting modal parameters of a normalized generic space vehicle. Next, the modal superposition principle is used with a low damping value for obtaining the elastic response of the vehicle to impulse excitation. The results for elastic displacement peaks are obtained for normalized rotational joint e exibilities of different magnitudes acting at different spanwise locations. The results show that locations of the joint with e exibility play an important role in determining the magnitude and location of the peak response. Further, it is found that e rst mode frequency results for various values and locations of joint e exibilities can possibly be unie ed into a single linear expression, based on the normalized stiffness distribution of the space vehicle. Finally, it is found that tip excitation is more critical than root excitation. Acknowledgment The work reported forms a part of investigations carried out for project IDYMOD-1, funded by the Structures Panel (AR&DB), Ministry of Defence, of the Government of India.