There are so many factors involved that any formula would be elusive. For metals for instance, these parameters are determined by the number and statistical distribution of dislocations, on the average 'crystal cell' sizes (which in turn is dependent on the prior history of thermal treatments etc.), on the inherent chemical properties (bond strengths etc.) ... The interplay of all these parameters is rather complex (I remember a calculation taking into account dislocation creep speed and so on, which however, despite its complexity, did not match measured values very closely.)
Your best bet is a number of measurements spread across a range of characteristic values, and interpolation between such data. A purely theoretical calculation would be overly complex, and the unavoidable modelling simplifications you'd have to make would have an inordinately negative effect on eventual accuracy and useability.
I am modelling for brick mortar interface. I need these parameters for the modelling of the bonded contact CZM modelling. These are the material properties:
Please note that the bond between brick and mortar in masonry elements is dependent on several factors such as brick properties (composition, strength, size, etc.), mortar properties (composition, water content, curing conditions, etc.) and workmanship (joints condition, etc.).
According to your material data, you can probably use the following values:
C1: if you mean in compression, this value can be the compressive strength of mortar or brick (which is minimum probably). If its in tension, you will need the results from tensile bond strength (mode I). As a rough estimation you can use between 0.1 to 0.2 MPa as Eurocode 6 suggests.
C2:As you do not have the experimental results, generally an average value of 0.012 N/mm is suggested to use.
C3: You can use the value of the shear bond strength tests. But note that this value depends on the normal stress on the joint. It varies with the changes of normal stress. So, you need to probably convert the results from the tests to your application. Cohesion can be used equal to 1.5ft as a rough estimation.
C4: As a rough estimation, you can use a ratio of C4/C3=0.1 in case if you don't have the experimental results.