Four holds

•Interference/tolerance
•Tension
•Torsion
•Mechanical

•Any combination of these holds makes a ‘locking system’.
•Repetition of any of these increases the strength of the structure.

Some things to consider for ultimate strength:-

•Material properties
•Torsional strength
•Compression strength
•Tensile strength
•Stress concentration areas/shearing

Working against us:-

•Gravity - is a natural phenomenon that gives weight to objects.
•Force - is that which can cause an object with mass to change its velocity/position.
•Mass - the degree of accelaration a body acquires when subject to a force.
•Inertia - resistance of an object to a change in its state of motion.