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Metallic Biomaterials - PDF

Added on - 11 May 2020

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Stem Hip Manufacturing1|P a g eManufacturing technology
Stem Hip ManufacturingContentsIntroduction......................................................................................................................................3Solution LO1.1................................................................................................................................4Solution LO1.2................................................................................................................................5Conclusion and recommendation....................................................................................................6References........................................................................................................................................82|P a g e
Stem Hip ManufacturingIntroductionThere is a wide use of metallic biomaterials in implant surgery of human body, the permanenceof any metal in the body set through bifunctionality and biocompatibility, but biocompatibilityconsideration is more important for selection of material for implants. The main concern isimplanted material corrosion and its effects on tissue around it. Titanium and Chromium are themetals which do not corrode in the body, other benefit of titanium alloy is that it has superiorfracture and fatigue resistance with traditional load bearing capacities[ CITATION Got11 \l 2057].In this assignment, first we must analyse the use if Ti-6Al-4V alloy for hip stem which is goingto use in Hip joint replacement, as per condition given in the assignment the normal load forstem is approximately 3 to 4 times of body weight, and in case of tripping or stumbling the loadcan be 10 to 15 times of body weight. Suppose average body weight is taken as 60 kg. It is alsogiven that this stem should bear load of 2 million steps every year. The data given in book for Ti-6Al-4V is its UNS – R56400, UTS – 1000 MPa, Ys – 925 MPa, Elongation % - 14, Reduction ofarea % - 30, all these data is available at annealed condition and room temperature[ CITATIONKal11 \l 2057 ].To calculate the fatigue life of the given hip stem first we must assume the dimension of objectespecially at neck area. The diameter of neck area is varying about 10 mm in starting to 13 mmfrom thicker section. We will proceed through stress life approach for fatigue life[ CITATIONSte16 \l 2057 ].Mass = 60 kg = 60*9.8 = 588NForce during walking = 588*3.5 = 2058 NMaximum force when falling = 588 * 12.5 = 7350 NArea of the neck where maximum pressure occurs = 0.07858 m2Minimum Stress = F/A = 2058/0.07858 = 26193 N/ m2Maximum stress = 7350/0.07858 = 93546 N/ m2Stress range = Δσ = 93546 – 26193 = 67353 N/ m2Stress amplitude = σA= (93546 – 26193) /2 = 33676 N/ m2Mean stress = σm= (93546 + 26193) /2 = 59869 N/ m2Load ration =R = 26193 / 93546 = 0.28No of cycle =Nf= 2 x 106/ year3|P a g e
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