Author: Robert Geißler

Concerning the Reliability of the Waggle Test

Dynamic parameters define a rigid body’s reaction to external forces. While their importance for a sword’s behaviour is known since the 19th century, many data sets of original swords, replicas and training weapons include mass and the centre of mass, but lack a third parameter such as moment of inertia, radius of gyration, or corresponding centres of oscillation/percussion. A third parameter, however, is required to calculate a rigid object’s response.

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Concerning the Dynamics of Swords

There are two major models that specify the point at which a sword should ideally hit its target. One model focusses on the sword’s vibration, particularly the nodes of the fundamental flexural vibration; the node which is closer to the sword’s point is often called centre of percussion. [1, 2] The other model, which is the subject of this work, considers translation and rotation as the components of a rigid body’s motion [3] upon impact. Several comprehensive articles on the rigid-body dynamics of swords exist, such as by Turner [4], Denny [5] and Le Chevalier [6]; those articles are highly recommended for a further reading on the consequences and possible applications of a sword’s analysis on the basis of rigid-body dynamics. The physical principles have been known since the 17th century. [7] Rigid-body dynamics were already applied in some historical sources on fencing [8, 9] to describe the point where a cutting weapon should ideally hit its target. This article is meant as a brief introduction of the subject for those who are not yet aware of the physics of fencing. Additionally, this article emphasises the importance of the moment of inertia for the behaviour of a sword, and encourages sword researchers and makers to determine and include this fundamental measure from which other parameters can be calculated. Motion of a Sword At any given time, a sword’s motion can be described as rotation about an axis, translation...

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Concerning the Rules of Tournaments

This article is to some extent a reply to Γιώργος Ζαχαρόπουλος’s article in which he points out the conflicting requirements that tournament rules have to address. Ζαχαρόπουλος examines tournaments under three aspects: safety, scoring and spectacle. Safety certainly is a crucial aspect as we want to simulate a process of mutual harming and killing while avoiding actual injuries. Regarding the set of rules, the question arises if possibly restricting or unrealistic equipment should be prescribed and if dangerous attacks such as targeting the hands or other insufficiently protected areas should be banned. Safety is a matter of discretion and...

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Concerning the Sharpness of Blades

A high level of sharpness of cutting tools is preferable, just as it is for edged weapons. While tools are generally used in well defined situations for which they are optimised, edged weapons, particularly those with longer blades, have to meet conflicting requirements. Within the scope of this work, influences on the sharpness of blades and their further effects as well as the necessary design trade-offs are evaluated. Factors of Sharpness While sharpness is an everyday concept, there is no uniform definition. It would, however, stand to reason to regard a blade as sharper, the less force it requires to cut a certain material or the deeper the cut becomes with a given force. Concurrently, the blade should not only be sharp, but should also retain its edge, i. e. the edge should withstand many cutting processes without a significant decrease in sharpness. Moreover, it is preferable to use a blade that withstands stress not only from ideal cutting processes – particularly when fencing. Depending on the respective application, an optimum compromise of sharpness and robustness has to be found. [1, 2] Several factors determine the sharpness of a blade, among them the properties of the steel, the relative motion of blade and target, the curvature of the blade, the edge angle, grinding and finish. Edge Radius and Finish McCarthy et al. [3] determined the dependence of the force \(F\) required for cut formation...

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