Unspaced vs. spaced breaking

Intro

When performing a strong support break, the breaking material, such as a wood board, clay tile, or concrete paver, is placed on and between two supports so the material is supported on two sides. When more than one piece of the material is used, the pieces of material are stacked one atop the other. There are two ways to stack the breaking material, unspaced and spaced.

Spacing

Spacing also called pegging is where two-spacers or pegs (such as wood pencils) are placed between each piece of material to create a gap between them. Stacks are spaced for many reasons:

The boards are easier to break so breakers can say that they broke a larger number of boards.
The stacks are taller creating the illusion of there being more boards that there actually is, thus making the break more visually impressive.
During breaking competitions, they make it easier to declare a clear winner since there is less a chance for there being a tie. Without spaces, there may be a point reached no competitors can break the stack. By using spacers, this point can be increased to help narrow the field of competitors.

One problem with spacing a stack is that the spacers add a variable that is not related to the ability of the breaker to break the stack. For a spaced stack to be totally broken, the setup and positioning of the spacers are critical, especially in a breaking competition where competitors must work closely with their team to ensure that each spacer is in the proper location and will not shift. If a spacer shifts from its location, it can disrupt the flow of the sequential breaking or the boards. Thus, performing a break using spacers is a team effort, not the individual effort of the breaker.

Elasticity of materials

The elasticity of the material to be broken affects the way an unspaced or a spaced stack reacts to the striking force. As it relates to breaking, there are basically two types of breaking material: elastic and inelastic.

Elastic. Elastic material, such a wood board, is pliable, which means it flexes and deforms when a force is applied and, when its tensile strength is exceeded, it splits apart and breaks on the opposite side of the one to which the force is applied. If the force is retracted before the material breaks, the deformation reverses and the material returns to its original shape. Some elastic materials have so much elasticity, that they are impossible to break using human strikes, such as plywood.
Inelastic. Inelastic material, such as a patio paver, is brittle, which means it does not flex or deform when a force is applied and, when it can no longer resist the force, it shatters. Breaking inelastic material requires a solid powerful strike that sends a shock wave of energy throughout the material that breaks the bonds between the molecules and causes the material to shatter. The strike need not travel through the material, the material just breaks apart and falls away. Some inelastic materials are impossible to break using human strikes, such as reinforced concrete.

Breaking a stack of elastic material, such as wood boards

How an unspaced, elastic stack breaks

When a wood board laying between two supports is struck in the middle by a continuous force, it flexes until it can bend no more and it begins to split. The splitting begins under the location where the force is applied and on the side opposite the one to which the force is being applied. The splitting propagates to the sides of the board along the grain and back through the wood to the side of the impact.

In an unspaced stack of boards, where each board (except for the bottom board) is laying directly atop each other, is struck by continuous downward strike, when the top board tries to flex, it pushes on the next board that pushes on the next board until the bottom board is reached. At this point, the bottom board bends and allows all the boards above it to continue to bend.

If the applied force is continuous and strong enough to cause the bottom board to break, then each board above the bottom board can break in turn until the entire stack is broken. This means that an unspaced stack breaks from the bottom up. However, to a viewer, the entire stack appears to break instantaneously.

If the striking force is not applied for a sufficient distance, it is possible for the bottom board to break but none of the boards above it will be broken. It is also possible, that a weaker board within the stack may split without the bottom board breaking. So, to break an unspaced stack, the breaker’s initial strike must be powerful enough to deform the entire stack all at once and be applied over enough a distance until the entire stack breaks.

The force needed to break a stack of unspaced boards is not the sum of the forces need to break each individual board’s thickness; it is nearly the same as the force needed to break one board of the stack’s thickness. Some say the force needed to break a stack of boards increases by a factor of 10 for each additional board. Thus, two boards are 10 times more difficult to break than one board, three boards are 10 times more difficult to break than two boards and 100 times more difficult to break than one board, etc.

How a spaced, elastic stack breaks

To create a spaced stack, two spacers are carefully placed between each board in the stack. Each spacer is placed adjacent to and parallel to the supported edges. This means that the spacers on each side form a direct connection from their edges down to the support. Effectively, this is like the board is resting on the support itself. Also, the spacers allow a board to bend a greater distance and start to break before it touches the board below it. Effectively this means, the striking force is breaking one board at a time. So, to break a spaced stack, the breaker only needs the initial strike to be strong enough to break one board, but that force needs to be applied for a great depth into the stack to ensure the each of the following boards are broken.

This way of striking is contrary to the striking fundamentals of most martial arts who teach that a strike is a quick, powerful, short action movement, such as that required to break an unspaced stack. Whereas, the strike used to break a spaced stack is more of a long, powerful push.

Breaking a stack of inelastic material, such as wood boards

Even though inelastic matter does no flex when being struck, a stack of inelastic material behaves much like a stack of elastic material when it is struck during a break. In an unspaced break, then strike but be powerful enough to immediately break the entire stack. Whereas, in a spaced stack, the strike is breaking the sections of the stack one at a time.

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Breaking>Unspaced vs. spaced breaking