BMEG 2613: Introduction to Biomedical Engineering

BMEG 2613: Introduction to Biomedical EngineeringHomework 5 (Due at the beginning of class 12/05/14)Problem 1 (12 points)a. Draw a generic stress-strain curve for a biomaterials and label each point on the stress-strain curve. Labelboth axes. (3)b. Write the expression for determining the strength of a material. (1)c. Draw the stress-strain curves of two materials A and B. Material A is highly ductile and iswell-suited for use in electrical leads as part of cardiovascular implants. Material B, on theother hand, is found to be extremely brittle. (2)d. An orthopedic bone plate is a flat segment of stainless steel used to screw two failedsections of bone together. The bone plate in the figure has a rectangular cross section, A,measuring 4.17mm by 12mm and made of 316L stainless steel.1) Calculate the axial stress produced by an axial load of 50N (2)2) Calculate the strain if the two punch marks in the middle of the plate have moved0.00075 apart. (2)3) What is the elastic modulus of the plate? (2)Problem 2 (9 points)Consider an athlete performing extension exercises of the lower arm tostrengthen the biceps muscles. The athlete is holding the weight W 1 = 150 N inthe palm of the hand, and the weight of the lower arm is W 2 = 20 N. The centerof gravity of the lower arm (point A) is located at a distance a = 7.5 cm from theelbow pivot O. The center of gravity of the weight held in the hand is located ata distance of b = 32 cm.a. Determine the net moment generated about the elbow joint for the positionshown in the figure (5).b. Determine the net moment about the elbow when the lower arm (OAB) islowered to make angles of 30 and 60°, respectively, with the horizontal (4).Problem 3 (8 points)Consider a simplified version of a hamstring strength training system forrehabilitation and athlete training protocols. From a seated position, the lower legmakes an angle θ with the horizontal. Point O represents the knee joint, point A thecenter of gravity of the lower leg, W is the total weight of the lower leg, F is themagnitude of the force applied on the lower leg in a direction perpendicular to thelong axis of the lower leg, a is the distance between O and A, and b is the distancebetween O and the line of action of F (as shown).a. Determine an expression for the net moment about O due to W and F.Remember that moment equals the force times the shortest distance between theline of action of the force and the pivot about which moment is being calculated (5).b. If a = 20 cm, b = 40 cm, θ = 30°, W = 60 N, and F = 200 N, calculate the net moment about O (3).Problem 4 (7)What are the three components of any measurement system? Define the following terms inherent to a biomedicalmeasurement system: Linearity, range, accuracy, and precision.