Pata sword with European blade

[mariusgmioc]

Originally Posted by Jerseyman

Hi Marius - I'd like to comment briefly on the tangential discussion regarding stiff versus flexible blades. I think I have to respectfully disagree with you.

Whether the blade is stiff or flexible you will still cut with the edge. If the blow is blocked then the contact presumably will be made with the edge. I'm not an engineer so don't have the terminology to describe this well I'm afraid, but the energy of the impact will be transmitted edge-to-edge through the blade - not flat to flat.

No matter how flexible a blade is, it is completely rigid in the edge-to-edge plane. So logically there should be little difference in the energy of the impact and its transmission into the attacker's arm, other than that caused by the blade being lighter.

Indeed, if the flexible blade had the effect you describe it would actually minimise the percussive power of the blow reducing its effect as a weapon.

If you were describing an angled deflection strike rather than a completely perpendicular one I could see some of what you're describing - but then you'd be minimising the effectiveness of the blow it seems to me as the blade would want to flex away from the target greatly reducing the power of the impact. Would that logically be a choice one would make?

Thank you very much for your observation!

You are right that for a perfectly straight blow the impact forces will be transmitted through the width of the blade, but how many blows are PERFECTLY perpendicular to the target surface in a real battle?! Even the slightest minute inclination would generate a transverse force that will tend to bend the blade. And even for a perfectly straight blow, at the moment of the impact the wielding arm will continue movement and necessarily have to change the angle, and then the blade will bend allowing the arm to continue the movement.

Regarding the relationship between elasticity and length, there is none. Elasticity is an intrinsic property of the material and is independent of the size or shape of the object. However, deformation is dependent on size an shape. So a coin will not bend even if you apply a huge force, but a long stripe made of exactly the same material will bend easily with the lightest force.