In a tension test the material breaks at a lower load than the ultimate load.?

Question

when the material withstands the highrst load,how does it breaks at the lower load?Pl note that the breakage is irrespective of the area of the speciman.

Answer 1

After reaching critical point of elastic limit , very less load is required to facture the specimen.

(Design Ultimate Load -The specific load that a structure, member or part must withstand without failure. )

(In a tensile test, a sample is strained at a constant rate and the stress needed to maintain this strain rate is measured. The stress and strain can either be measured in terms of engineering stress and strain or true stress and strain. The elastic modulus, the ultimate tensile stress, the fracture stress, the modulus of toughness, and the modulus of resilience can all be determined from a tensile test.)

Answer 2

specimen tests that break at lower loads, are sometimes engineered that way, max load strength in an individual unit is not always desired, such as a break away unit, where static strength is ok, but it shears when shock is applied; also when building items intended for tactical booby traps,such as rope bridges where the enemy is using it, causing moral decay in the oppositions attitude towards advancing to your positions.