N.K. Das Talukder

Springback analysis in torsion of rectangular strips

Abstract A theoretical analysis of the springback of narrow rectangular strips under torsional loading is presented. The theoretical analysis is supported by experimental results for different materials, different thicknesses and different lengths, keeping the width of the strips constant. Finally an analytical generalized expression relating angle of twist and twisting moment and residual angle of twist per unit length for rectangular bars under plastic torsion is obtained in non-dimensionalized form.

Torsional springback in square section bars of nonlinear work-hardening materials

Abstract This paper deals with the torsional springback problems of bars of strain-hardening material with arbitrary cross-section. Using the deformation theory of plasticity, a numerical scheme with a Ramberg-Osgood type stress-strain relationship has been prepared which determines the elastic-plastic boundary in addition to springback in the bars. The results have been verified experimentally with mild-steel bars having square cross-section and the experimental results have been found to agree well with the theoretical results obtained numerically.

Springback analysis of torsion of L-sectioned bars of work-hardening materials

Abstract This paper deals with the torsional springback problems of L-sectioned bars of non-linear work-hardening materials, the properties of which can be modelled by a deformation theory constitutive equation of the Ramberg-Osgood type. The results have been verified experimentally with mild steel bars. It was found that the experimental results agree well with theoretical results obtained numerically.

Parametric assessment of torsional springback in members of work-hardening materials

Abstract The paper deals with the torsional springback problem of bars of strain-hardening materials with arbitrary cross-sections. Using the deformation theory of plasticity, a numerical scheme based on the finite difference approximation has been proposed. The growth of the elastic-plastic boundary and the resulting stresses while loading, and the torsional springback and the residual stresses after unloading, are calculated. The results are verified experimentally with mild steel bars having a square cross-section. The experimental results are found to agree well with the theoretical predictions obtained numerically.

Springback analysis of thin rectangular bars of non-linear work-hardening materials under torsional loading

A theoretical analysis of the springback of narrow rectangular strips of non-linear work-hardening material under torsional loading has been carried out. This theoretical analysis is supported by experimental results for rectangular mild steel strips of different thicknesses and lengths. Finally an analytical generalized expression relating angle of twist to twisting moment and residual angle of twist per unit length for rectangular strips under plastic torsion is obtained in non-dimensionalized form. A comparison between the results obtained for bars of non- linear and linear work-hardening materials loaded under torsion is also made.

On the arrangement of rolls in cross-roll straighteners

Abstract A simplified analysis of the cross-roll straightening processes is made and roll arrangements for higher throughput, speed and standard of straightness are suggested.

Cross-roll straighteners and their performance

Abstract Presented in this paper is an analytical description, indicating clearly the merits, demerits and limitations in performance of different types of cross-roll straighteners. The major factors considered are: the effective moment acting on the product; the degree of straightness of the product; the throughput speed; and the separating forces acting on the rolls.

On fringe multiplication by superimposition of negatives

The mechanism of superimposition of negatives has been explained fully and it has been shown that though the technique gives the desired results, the governing equations derived by Dally and Ahimaz for the fringemultiplication technique contain inaccuracies.

Method for production of uniform-intensity field of light

It has been shown that a processed negative, on a particular type of film and exposed to a field of light with nonuniform intensity will make the intensity of the resultant field of light uniform, when placed in series in the setup satisfying certain conditions.

Correlation between attenuation and strain in cross-plied GRP composites under tensile loading

Abstract A method is presented for the determination of strain in cross-plied glass fibre-reinforced epoxy resin composites under tensile loading by ultrasonic testing. The method has been verified experimentally and has been found to be satisfactory.