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Deformation in a Circular Shaft

Deformation in a Circular Shaft

One of the distinctive characteristics of circular shafts is their ability to maintain their cross-sectional integrity under torsion. In other words, each cross-section continues to exist as a flat, unaltered entity, simply rotating like a solid, rigid slab. To understand the distribution of shearing stress within such a shaft, consider a cylindrical section inside this circular shaft. This section has a length of L and a radius of R, with one end fixed. The radius of the cylindrical section is...

Stresses in a Shaft

Stresses in a Shaft

The shaft PQ is subjected to a twisting force when equal and opposite torques are applied on either side. A section that cuts perpendicular to the shaft's axis at any arbitrary point R is examined to understand this. When the free-body diagram of the QR segment is analyzed, it reveals the shearing forces exerted by the PR portion onto the QR segment as the shaft experiences twisting.
Applying equilibrium conditions to the QR segment establishes that the internal shearing forces within the...

Residual Stresses in Circular Shafts

Residual Stresses in Circular Shafts

In materials that exhibit elastic and plastic behavior, known as elastoplastic materials, residual stresses can accumulate when these materials experience plastic deformation. This deformation arises from either high levels of shearing stress or significant strains. Residual stresses are internal stresses that persist within a material after removing the external force causing deformation. This phenomenon is demonstrated when observing the behavior of a shaft under torque; notably, the shaft's...

Plastic Deformation in Circular Shafts

Plastic Deformation in Circular Shafts

When materials are subjected to forces that surpass their yield strength, they undergo a process known as plastic deformation. This results in a permanent alteration or strain in their structure. This concept can be specifically applied to circular shafts, where the deformation leads to a change in its shape. The precise evaluation of this plastic deformation requires understanding the stress distribution within the circular shaft, which is achieved by calculating the maximum shearing stress in...

Circular Shaft - Stresses in Linear Range

Circular Shaft - Stresses in Linear Range

Consider a scenario where a circular shaft is subject to torque that remains within the boundaries of Hooke's Law, avoiding any permanent deformation. So, the formula for shearing strain is revisited. This formula is multiplied by the modulus of rigidity, and then Hooke's Law for the shearing stress and strain is applied. As a result, the equation for shearing stress in a shaft can be derived.

Transmission Shafts: Problem Solving

Transmission Shafts: Problem Solving

Designing a solid shaft that transmits power from a motor to a machine tool involves a series of calculations to ensure the shaft can withstand the stresses applied by bending moments and torques. First, calculate the torque exerted on the gear, considering the power transmitted by the shaft and its rotational speed. Following this, compute the tangential forces acting on the gears, which directly relate to the torque and the gear radius.
Next, use bending moment diagrams for the shaft to...

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Related Experiment Video

Updated: May 27, 2026

Design and Implementation of a Bespoke Robotic Manipulator for Extra-corporeal Ultrasound

Design and Implementation of a Bespoke Robotic Manipulator for Extra-corporeal Ultrasound

Published on: January 7, 2019

Endoscope shaft-rigidity control mechanism: "FORGUIDE".

Arjo J Loeve¹, Dick H Plettenburg, Paul Breedveld

¹Department of BioMechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, 2628 CD Delft, The Netherlands. a.j.loeve@tudelft.nl

IEEE Transactions on Bio-Medical Engineering

|November 17, 2011

Summary

This summary is machine-generated.

A novel FORGUIDE mechanism offers controllable rigidity for flexible medical shafts. This innovation uses cable friction within a spring and inflated tube to enable adjustable stiffness, enhancing medical device performance.

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Area of Science:

Medical Engineering
Robotics
Materials Science

Background:

Advancements in flexible endoscopy and medical technologies necessitate compact, slender shafts with adjustable rigidity.
Existing solutions often lack the desired balance of flexibility and controllable stiffness.

Purpose of the Study:

To develop and validate a novel compact mechanism, FORGUIDE, for actively controlling shaft rigidity.
To create a mathematical model for understanding and optimizing the FORGUIDE mechanism's performance.

Main Methods:

Development of the FORGUIDE mechanism utilizing cable friction between a spring and an inflated tube.
Creation of a mathematical model to analyze the working principle, predict maximum rigidity, and tune design variables.
Construction and bench testing of a prototype FORGUIDE shaft.

Main Results:

The FORGUIDE mechanism successfully demonstrates controllable rigidity in a flexible shaft.
Mathematical modeling provided insights for performance enhancement through design variable optimization.
Bench tests confirmed the mechanism's reliability and simplicity in controlling shaft stiffness.

Conclusions:

The FORGUIDE mechanism presents a viable solution for achieving actively controlled rigidity in slender shafts.
This technology has significant potential for applications in flexible endoscopy and other medical devices.
Further design refinement based on the mathematical model is expected to yield substantial performance improvements.