Using a "high strength" bolt? Take a systems approach and consider not only bolt strength but also washer strength, nut strength, and joint strength. This washer, used on a propeller bolt, crushed, resulting in loose propeller bolts - even thought the safety wire was preventing the bolts from rotating!
Picture to left shows what happens when you tighten the bolt past the materials compressive yield strength. Instead of springing back and holding the fastener tight (as occurs in a normal joint), the material collapses under the strain, leaving the fastener loose. Lock washers will not function without joint tension.
To calculate bearing stress (surface pressure), you take the bolt tension and divide by the contact area between the bolt head and the part. You then compare this value to the allowable surface pressure for the joint material.
A rule of thumb is that the allowable surface pressure is approximately equal to the material's ultimate tensile strength (due to elastic and plastic constraint from the surrounding material). Even if you reach the pressure limit, that just means you begin indentation of the part, which does not necessarily mean part failure. You will need to decide what the part limits are with respect to static and cyclic loading, temperature exposure, etc.
A spark plug gasket is a good example of using the joint material properties to advantage. Spark plug gasket forms an air-tight seal by using the work hardening properties of copper. A new gasket is soft and as the plug is tightened, the copper yields and flows into small gaps creating an airtight seal. As the copper deforms it gets stronger by a process called 'work hardening". Hardening prevents further yielding and this prevents the spark plug from loosening in service.
One reason to always replace copper gaskets is that once deformed and work hardened, it must be returned to the soft (annealed) state before it can again flow into the small gaps. Annealing will soften the copper but it won't restore its original shape.
