Reinforced discontinuous bend subjected to uniform internal pressure: Effect of reinforcing ring stiffness

Abstract

Abstract

This paper deals with the results of an experimental study undertaken to assess the stress-reducing effect of internally bracing a traditional constant-depth elliptical reinforcing ring.

Stress profiles, calculated from strain readings recorded by electrical-resistance foil strain gauges bonded to inner and outer surfaces of the cylindrical limbs of model Araldite bends, are presented for four reinforcement conditions:

constant-depth (traditional) elliptical ring;

constant-depth ring with internal cruciform bracing;

constant-depth ring with a single brace across the minor diameter;

perfectly rigid reinforcing plate.

When a traditional reinforcing ring was used the greatest stress-concentration factor (referring to circumferential membrane stress remote from the discontinuity as unity) was found to be 4.15. This was reduced to 2.90 by the use of a ring with a single minor-diameter brace and was further reduced to 2.70 when a ring having a cruciform brace set across major and minor diameters was used. The effect of an infinitely rigid reinforcement was to reduce the maximum stress-concentration factor to 2.60.