Final answer:
A rectangular strain gage rosette is used to measure strains on the surface of a material, and in this case, it is being used on an aluminum alloy part. The strains are given in different directions and indicate compressive strain. The strains can be used to calculate other properties of the material.
Step-by-step explanation:
A rectangular strain gage rosette is a device used to measure strains on the surface of a material. In this case, it is being used to measure strains on the free surface of an aluminum alloy part. The strains are given as εᴬ = -1550 με and εₛ = -3800 με.
εᴬ and εₛ represent the strains in different directions on the surface of the part. The negative sign indicates that the part is experiencing compressive strain in those directions. The strains can be used to calculate other properties, such as stress, using equations and principles of material behavior.