Can a sword cut a person in half?

Answer 1

The sword may be very sharp but it is unlikely that it could literally cut a person in half, especially since it can be assumed the "victim" would be a moving target. The space between the last rib to the pelvic bone is only about 18" to 24" and at the rear (posteriorly) are the bones around the spinal cord. A slicing motion would have to be very, very precise to hit at exactly the right spots for a blade to completely break a spinal bones and cut the spinal cord. If the hit was high, the ribcage protects the upper body; if low, the pelvic bone is thick and a sword would bounce off the bone. As well, many of these bones have curved areas, making it harder to make a solid strike.

To amplify on the above, if the question is asking if a single blow from a sword could cut a person in half (i.e. a top and bottom half, not a left/right half), the answer is an unqualified NO.

As implied above, such a cut would have to completely avoid hitting bone, as no person is strong enough to be able to cut through several inches of solid bone PLUS a foot or more of flesh. This means the only way even possible would be a slice through the abdomen, starting somewhere below the rib cage and above the hip bone. Such a cut would have to be precise enough to pass through the gap between spinal column bones (such gaps being 2-4mm or so at best). Also, the sword in question would have to be both extremely sharp, and quite strong. It would have to be sharp enough to minimize resistance when slicing flesh, yet have a blade strong enough to transmit enough power from the sword wielder's movement to overcome the resistance from the sliced flesh it does encounter.

About the only sword that I can think of that could possibly have the ability to do so would be the Japanese katana sword - it can be used two handed (to maximize power), is considerably sharper than the majority of sword blades (about the only contender on that front is the Renaissance and later era broadsword/sabre), and also has a sufficiently strong blade to withstand the shock of resistance when slicing.

All that said, the total amount of flesh such a blow would have to cut through (at least a full square foot of flesh, in cross-section) leads to a power requirement for the blow that is almost certainly beyond even the strongest human. Lesser feats such has amputating a arm or even leg, or possibly decapitating an opponent, are possible, as the total amount of flesh (and possibly bone) in those cases would be less than a quarter of the amount required to hack through someone's torso.

From a mechanical physics standpoint, the ability maintain the speed of the blade's movement is critical to cutting - that is, the faster the sword blade is moving, the easier it is to cut flesh. However, the flesh itself exerts a drag on the blade, slowing it down. Thus, it is almost certain that the relationship of sword speed to depth of cut is a geometic one, rather than a linear one. This means, that a blade initially moving at X ft/s which can cut through Y inches of flesh, would likely have to be moving at 4X ft/s to cut through 2Y inches of flesh, or something similar. So, cutting through a torso would likely require something like 16 times the power required to cut through a leg. And, amputating a leg is already extremely difficult to do.

As a final observation: swords are used in one of three methods: slashing (drawing the length of the blade down the opponent), stabbing (using the sharp tip to pierce an opponent), or bludgeoning (cauing mostly blunt-force trauma, as the traditional Scottish Claymore does). Cutting through something is called Cleaving, and is almost always done far better by an axe blade than a knife blade (which is functionally what a sword has).