Beams AB and CDE are connected using rigid link DB with hinges (or moment releases) at ends D and B (see figure a). Beam AB is fixed at joint A and beam CDE is pin-supported at joint E. Load P =150 lb is applied at C.

(a) Calculate the deflections of joints B and joint C. Assume L = 9 ft and E_I =127,000 kip-in².

(b) Repeat part (a) if rigid link DB is replaced by a linear spring with k = 20 kips/in (see figure b).

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Polysilicon anchor Dielectric substrate Electrode Cantilever beam L b h L M B Based on Gary O'Brien, David J. Monk and Liwei Lin, "MEMS cantilever beam electrostatic pull-in model, Proc. SPIE 4593, Design, Characterization, and Packaging for MEMS and Microelectronics II, 31 (November 19, 2001).