What is the difference between Environment Temperature, Zero-strain reference temperature?
1. "Zero-Thermal-Strain Reference Temperature", found in Workbench Engineering Data when you enter temperature-dependent coefficients of thermal expansion, is what was used as a reference point when material properties were obtained during the test. The CTE (coefficient of thermal expansion) values you put in the table assume that at this temperature the thermal strain is zero. It appears for tabular input only because you use the default input of secant CTE, so they always need some reference as "zero point" unless you have a single CTE for all temperatures. If you choose to provide instantaneous CTE instead, you need no reference temperature.
2. "Environment Temperature" found in the Details view of the analysis branch is the temperature at which thermal strains are zero in the current analysis (TREF command).
If temperature-dependent CTEs in Engineering Data were determined using a different reference temperature, these CTEs have to be updated for a new reference (this is performed automatically at execution with the MPAMOD command).
3. The "Reference Temperature" found in the Details view of the body is basically the same as the "Environment Temperature". The reference temperature could be defined per body (MP,REFT,), and this reference temperature has priority over the one specified as "Environment Temperature" (TREF) if the two values differ.