Hi guys

Within the Material Properties window, I can see that the yield strength of AL6061-T6 is stated as 275.79 MPa. However, when I run a static simulation and calculate FOS based on Max von Mises Stress, it states that the yield strength of the same material is 55.15 MPa. Why is there this difference in the yield strength within the same material? Sorry if this is a noob question... Thanks in advance for any help.