Materials for Biomedical Engineering. Mohamed N. Rahaman

550−1240 12−55 50−150 2−3 CoCr (F75^b; as‐cast/annealed) 8.3−8.5 210 448−517 655−889 10−20 50−100 3−4 CoCr (F799^b; hot forged) 8.3−8.5 210 896−1200 1399−1586 5−15 50−100 3−4 Al₂O₃ 3.98 350−400 360−400 2000−3000 <0.1 4−5 18−20 ZrO₂‐toughened Al₂O₃ (ZTA) 4.40 300−350 700−1000 4000−4500 <0.1 6−10 16−20 YSZ 6.05 200−220 1000−1200 <0.1 6−12 12−13 Si₃N₄ 3.2 290−310 600−1000 <0.1 6−10 14−15 Hydroxyapatite 3.16 90−120 80−200 100−200 500−1000 <0.2 ~1.0 5−6 β‐TCP 3.07 35−90 100−150 460−700 UHMWPE 0.93−0.94 0.5−1.3 20−30 30−40 130−400 2−3 0.06−0.09 PMMA 1.2 2.5−3.2 60−80 4−5 1−1.5 0.1−0.2 Cortical bone (porosity 5−10%) 1.7−2.0 10−20 125−150(//) 135−190 130−180 1.5−3 2−12 0.7−0.8(//) 50(⊥) 0.5−0.6(⊥) Trabecular bone (porosity 50−90%) 0.1−5 1−5 10−20 2−12 0.1−0.8

      These data correspond to those for the dense (pore‐free) metals and polymers and for dense or nearly dense ceramics (<5% porosity) at room temperature (approximately 25 °C). The mechanical properties of metals are dependent on their microstructure and heat treatment whereas for ceramics, they are dependent on the amount of residual pores and grain size.

      YSZ, yttria‐stabilized zirconia (3 mol% Y₂O₃); ZTA, alumina matrix composite containing 15−20 vol% tetragonal ZrO₂ particles; UHMWPE, Ultrahigh molecular weight polyethylene; PMMA, polymethyl methacrylate.

      ^a CP, commercial purity.

      ^b ASTM designation.

      ^c Strength increases but elongation to failure decreases from Grade 1 to Grade 4.

//, parallel to long direction.

⊥, perpendicular to long direction.

      The negative sign is included because most materials contract in the direction perpendicular to a tensile stress, that is, the strain in the lateral direction is opposite in sign to the strain in the tensile direction. Consequently, ν is positive for most materials. Values for the Poisson’s ratio for the majority of materials are in the range ~0.25–0.40.

      There are other forms of elastic behavior, although the stress versus strain curve is not a straight line or the unloading part of the curve does not follow the same path as the loading part. Polymers show elastic behavior