Vehicle body and frame assembly including energy absorbing structure

A vehicle frame assembly comprising:

• a plurality of structural members that are connected together to form a vehicle frame assembly, at least one of said structural members having a hollow portion;
• and
• an energy absorbing structure secured to said hollow portion of said one of said structural members, said energy absorbing structure including:
• a first portion having a first generally uniform dimension, said first portion extending within said hollow portion of said one of said structural members;
• a second portion extending from said first portion and having a second generally uniform dimension that is greater than said first generally uniform dimension of said first portion so as to define a first shoulder between said first portion and said second portion that abuts said hollow portion of said one of said structural members;
• and
• a third portion extending from said second portion and having a third generally uniform dimension that is less than said first generally uniform dimension of said first portion so as to define a second shoulder between said second portion and said third portion;
• wherein said second portion has at least one stiffening rib formed therein and said third portion has at least one stiffening rib formed therein that is discontinuous with said stiffening rib formed in said second portion;
• said energy absorbing structure adapted to be deformed during a collision such that said third portion is moved within said second portion to absorb energy.