Plastic tubing bending

Bending (Tubes, Profiles), Fig. 8 Stress distribution during pure bending with plastic deformation... 

Fiber Cans and Tubes. The basic material used for fiber tubes and cans is a bending board. The body of a fiber can usually is of paperboard and the ends usually are of metal, paperboard, or plastic. The constmction of the body may be one of three general types sprial-wound tubes and cans, convolutely wound tubes and cans, or laminated or lap-seam cans. 

Physical stress is easy to understand because we can feel, observe, or relate to the events that develop physical stresses. Pulling hard on a plastic tube attached to a hose connection, bending glass, and watching an item fall to the floor are all easily understood (or observed) physical stresses. 

It is assumed that the bending moment applied to the root section of the tube is the plastic limit moment. Let the neutral axis be defined by the angle... 

Move the capillary to a horizontal position. Position the filament 1-2 mm below the capillary tip. Move the filament close to the pipet, and heat to bend the capillary by about 15° to the horizontal. One holding pipet lasts one microinjection session and is not reused. Large numbers can be made in advance and stored in a sterile plastic tube. 

---