I have a multi-disk rotor and need its torsional behaviour mapped out so I can confidently avoid any critical-speed issues. What I need from you • A clear derivation of the governing equations and the model you adopt for the individual disks and shaft segments. • Calculation of natural torsional frequencies and identification of the critical speeds across my operating range. • Campbell diagram or equivalent visual that highlights any resonance crossings. • A concise report (PDF) explaining assumptions, step-by-step calculations, and conclusions, plus the raw calculation file (Excel, MATLAB, or Python script) so I can reproduce the results. Acceptance criteria • Calculated critical speeds must be traceable through your worksheets with units and consistent notation. • Any simplifying assumptions (e.g., negligible disk inertia coupling) are stated and justified. • Results align within industry-standard tolerance when spot-checked against hand calculations. If this fits your analytical toolkit, I’m ready to supply geometry, inertia data, and operating speed range as soon as we start.