Browsing by Author "Houghton, D. S."

Now showing 1 - 9 of 9
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    An analysis of an unstiffened cylindrical shell subjected to internal pressure and axial loading
    (College of Aeronautics, 1961-03) Houghton, D. S.; Johns, D. J.
    General equations are obtained for the deflections and stresses in long thin unreinforced cylinders, which are subjected to an axial load and internal pressure. By making suitable simplifying assumptions, results are presented which show the variation of the structural weight parameter with the structural axial loading index, for both pressurised and unpressurised shells. An allowance is made for the effects of shell initial eccentricities on the buckling stress coefficient K, in accordance with R. Ae.S. data sheet 04.01.01. Extreme cases are considered, in which the shell is assumed to be either fully effective (K = 0.6). 0:. completely ineffective (K = 0), in resisting axial compressive loads. For this latter case, complete pressure stabilisation of the shell is considered, and it is shown that the weight penalty involved in using this design philosophy, is negligible for a certain range of the structural loading index. A simple modification to the analysis for this case, i.e. K = 0, is made to allow for the effect of an external longitudinal bending moment.
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    The analysis of reinforced circular and elliptical cutouts under various loading conditions
    (College of Aeronautics, 1961-07) Houghton, D. S.; Rothwell, A.
    The effect of reinforced cutouts in a plane sheet under various loading conditions is considered, and a number of experimental results are given for circular and elliptical cutouts with a uniform plate reinforcement, subjected to various systems of biaxial tension and pure shear. These experiments were conducted using a plane loading frame, and the results are compared with the theoretical plane stress solution. For the circular cutout the effect of neglecting the bending stiffness of the reinforcement is considered. Some additional experiments were carried oUt on a 60 in. diameter pressurised cylinder containing an elliptical hole reinforced according •to Mansfield's neutral hole theory. The strains in the sheet in the region of the neutral hole are .compared with the corresponding strains in the uncut sheet. The experimental results obtained generally show a good agreement with the theory.
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    Buckling due to thermal stress of cylindrical shells subjected to axial temperature distributions
    (College of Aeronautics, 1961-05) Johns, D. J.; Houghton, D. S.; Webber, J. P. H.
    Thermal stress distributions in uniform circular cylindrical shells due to axial temperature distributions are investigated. The discontinuity effect due to the presence of a cooler stiffening bulkhead is considered, and the possibility of thermal buckling of the shell due to the circumferential discontinuity stress is examined. The buckling analysis is based on Donnell's shell equation, and particular attention is given to shells having clamped edges. An experimental investigation of this buckling problem is discussed, and the results obtained are seen to agree reasonably well with theory.
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    The effect of curvature on the stress concentrations around holes in shells
    (College of Aeronautics, 1962-05) Houghton, D. S.; Rothwell, A.
    An experimental investigation has been carried out to investigate the effect of curvature on the stress concentrations around holes in shell structures. Two methods have been employed: - (I) Araldite cylinders, containing holes of various shapes, subjected to axial tension, internal pressure and torsion were examined by the photoelastic frozen stress technique. (2) Aluminium alloy curved panels and hemispheres were used in conjunction with miniature electrical strain gauges. The results are compared with the theoretical solutions and suggest that the curvature effect can be significant, particularly for the case of shear or biaxial loading.
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    The influence of frame pitch and stiffness on the stress distribution in pressurised cylinders
    (College of Aeronautics, 1958-02) Houghton, D. S.
    An analysis is made of the stresses occurring in stringer reinforced cylinders due to the restraining action of the frames. Graphs are presented showing the effect of variation in frame pitch and stiffness, on the bending moment and shear force in the skins, and the hoop stress in the skins between frames. The results are used to show how the optimum structural geometry can be chosen for any given stress ratios.
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    Linear buckling of an axially reinforced pressurised cylinder
    (College of Aeronautics, 1960-10) Houghton, D. S.; Johns, D. J.
    An analysis is presented using small deflection theory for the buckling of a pressurised, axially reinforced cylinder, which is subjected to axial compression. Various approximations to the analysis are discussed and some results are presented which show the effects of internal pressure and various structural parameters on both panel buckling and overall buckling.
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    A note on the discontinuity stresses at the junction of a pressurised spherical shell and a cylinder
    (College of Aeronautics, 1958-01) Houghton, D. S.; Chan, A. S. L.
    An analysis has been made of the forces and moments occurring at the junction of a pressurised spherical shell with an intersecting cylinder. The additional effects of having a temperature gradient along the length of the cylinder and the effect of a jointing ring have been considered.
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    Optimum design of a band reinforced pressurised cylinder
    (College of Aeronautics, 1961-04) Houghton, D. S.
    The surface stresses in band reinforced cylindrical pressure vessels are examined, and an equivalent stress determined by using the Mises- Hencky criterion. By comparing the equivalent stress to the band stress, the efficiency of the structural material can be established, and by equating these stresses to their respective yield stresses, the theoretical maximum strength of the structure can be found. Once the material properties of the shell and the reinforcing bands have been specified, the optimum structural layout can be determined.
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    The stresses around some unreinforced cutouts under various loading conditions
    (College of Aeronautics, 1961-03) Houghton, D. S.; Rothwell, A.
    A number of experimental results are given for unreinforced circular; elliptical and square cut-outs with rounded corners, under a variety of loading conditions. These results are then compared with the infinite flat plate solution, using the complex stress function and the method of conformal transformation. It is generally considered sufficiently accurate for a plane stress solution to be applied to problems of cut-outs in cylindrical shells, provided that the cut-out dimensions are small compared with the radius of curvature of the shell. In order to investigate this effect of shell curvature, a number of experiments were carried out on cutouts in two pressurised cylinders, and to obtain a wider range of loading conditions, a further series of experiments was conducted using a plane loading frame. Two aluminium alloy cylinders, of 44 in. and 60 in. diameter, were pressurised using air, and the stress conditions around the cutouts examined using electrical resistance strain gauge techniques. The plane loading frame enabled any combination of bi-axial tension and shear to be applied to a plane sheet containing the cut-out under examination. In this way the effects of body forces, which might arise in such applications as aircraft and nuclear reactors, could be simulated. The experimental results which are given generally show a close agreement with the theoretical plane stress solution.