An automotive designer is proposing using a 50 cm section of rigid stainless steel fuel line. the fuel line has 1.0 cm outer diameter and 3 mm wall thickness. (area =6.60e-5 m^2 and area moment of inertia is 4.78e-10 m^4) one end of the tube is cantilevered (fixed) from the fuel sender and the other end rests (pinned) on the vehicle frame. a flexible hose is attached after the pinned end. during operation, the pinned end of the fuel line moves +/- 1 cm (perpendicular to the fuel line). the fuel line material has yield strength of 276 mpa and ultimate strength 572 mpa.
make a sketch of the problem. answer the following questions:
1. is there a risk of fuel line fatigue failure?
2. because fuel line failures are likely to have fatal consequences, a factor of safety of three is specified for infinite life.
3. after a required design change to the frame cross section, the nominal position of the pinned end was moved up 2 cm (perpendicular to the fuel line). during operation, the pinned end of the fuel line still moves +/- 1 cm. is there a risk of fuel line failure?
4. verify the factor of safety of three for infinite life after the design change to the frame.
5. the designer did not want to design any fixed bends in the fuel line because it would cause stress concentrations. make a recommendation that would improve the design of the fuel line.