Secondary stress. A secondary stress is any stress in the structure which is not a primary stress or peak stress. Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global Standards.
Digger bees are sometimes classified in the family Anthophoridae along with the carpenter bees. These hairy bees range from 5 to 25 mm in length and, like other members of this family, the females use scopae (stiff hairs) to carry pollen. Most species nest in the ground or in vertical banks, often in sandy soil. Some species waterproof their brood cells with secreted waxy or oily material.
Variances in Appearance. Carpenter bees, species in the genus Xylocopa, and bumblebees, members of the genus Bombus, are both large, fuzzy bees, and they are often mistaken for one another in a garden. The easiest way to tell the difference between a carpenter bee and a bumblebee is to look at the bee's abdomen. The carpenter bee's abdomen is shiny, black and devoid of hairs on its upper surface. A bumblebee's abdomen is hairy and usually has yellow markings.