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A series of multiaxial ratcheting-fatigue interaction tests have beencarried out on Sn-3Ag-0.5Cu lead-free solder specimens. All tests were conducted undercyclic shear strain with the constant axial stress at the room temperature with the shearstrain rate of 5×10-3/s. It was found that the ratcheting strain increased with increasingaxial stress and shear strain amplitude while the fatigue life decreased at the same time.The ratcheting strain rate was linear with axial stress in double logarithmic coordinate.The Gao-Chen model which adopted the maximum shear strain and the ratchetingstrain rate as the damage parameter predicted the multiaxial ratcheting fatigue lifewell.