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The aerodynamics of a cascade of airfoils oscillating in torsion about the midchord is investigated experimentally at a large mean incidence angle and, for reference, at a low mean incidence angle. The airfoil section is representative of a modem, low aspect ratio, fan blade tip section. Time-dependent airfoil surface pressure measurements were made for reduced frequencies of up to i.2 for out-of-phase oscillations at a Mach number of 0.5 and chordal incidence angles of 0°and 10°; the Reynolds number was 0.gx10 6. For the 10°chordal incidence angle, a separation bubble formed at the leading edge of the suction surface. The separated flow field was found to have a dramatic effect on the chordwise distribution of the unsteady pressure.In this region, substantial deviations from the attached flow data were found with the deviations becoming less apparent in the aft region of the airfoil for all reduced frequencies. In particular, near the leading edge the separated flow had a strong destabilizing influence while the attached flow had a strong stabilizing influence.

An analysis is presented for the determination of the range of “safe” temperature increases in a railroad track, in order to prevent vertical buckling. A general nonlinear formulation of the problem is derived by using the theory of elasticity, the principle of virtual displacements and the variational calculus for variable matching points. In order to simplify the solution it is shown, on a closely related problem, that a number of highly nonlinear terms may be neglected without affecting the final results. The obtained nonlinear formulation for the railroad track is simplified accordingly. The resulting nonlinear equations are then solved, in closed form, and the obtained results are presented graphically.

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Recently, the problem of the mechanical buckling of a long beam resting on a frictionless rigid foundation and subjected to a uniform lateral loading was analysed using a linear formulation. The purpose of this paper is to show that the linear analysis is not sufficient for predicting a correct post-buckling response and that a completely nonlinear formulation is needed. The problem is formulated as a variational problem with variable end-points. The resulting nonlinear boundary value problem is solved numerically using the ‘shooting method’. The nonlinear solution indicates the presence of a lower buckling load, before which the only state of equilibrium is the undeformed state.