Table 1 Stress relaxation properties of selected soft tissues that exhibit substantial stress relaxation.

Tabulated values from stress relaxation tests of selected tissues. ti and tf, respectively, indicate the time when stress relaxation tests started and ended. Ei is the initial modulus measured at ti in units of kilopascal. The stress relaxation time, τ1/2, indicates the time at which the initial stress relaxes to half its original value. Ef /Ei is the normalized relaxation modulus measured at tf. Times and stresses reported here are approximate. Note that, in some stress relaxation tests, the stress reached an equilibrium stress by the end of the tests, while in other tests, the test may not have been sufficiently long for the stress to reach an equilibrium value or zero. For testing method, comp. and indent. represent compression and indentation, respectively. (–) indicates not reported.

Tissue typeAnimalStrain (%)Initial modulusStress relaxation timeFinal relaxation
modulus
Testing methodReferences
ti (s)Ei (kPa)τ1/2 (s)tf (s)Ef/Ei (norm)
Bone marrowRat150.1105000.25Comp.(1)
Breast cancerHuman400.011.81035000.02Indent.fig. S1
Murine2–100220–501800.2–0.4Indent.(11)
AdiposePorcine0.10.01350.1500.06Shear(9)
Rat150.110010000.5Comp.(1)
BrainBovine10.60.010.715000.21Shear(10)
Rat100.010.551400.18Shear(2)
150.110010000.25Comp.(1)
LiverBovine0.130.0150.12000.08Shear(14)
Rat2570.06–0.085010000.25Shear(15)
150.110010000.3Comp.(1)
Embryonic tissuesChicken015–701700.2–0.5Comp.(12)
MuscleMurine10101.25706000.3Shear(16)
HematomaHuman15020010000.3Comp.(13)
SkinRat165015000.47Tension(7)
Swine5–150200–120012000.3–0.5Tension(8)
Human300120090000Radial tension(6)