+ B. Using a similar notation, decoupling could be formulated as AB - B = A. Decoupling procedures are often required to remove substructures that were added for measurement purposes, e.g. to fix the structure. Similar to coupling, a primal and dual formulation exists for decoupling procedures. Primal disassembly As a result of the primal coupling, the impedance matrix of the assembled system can be written as follows: Using this relation, the following trivial subtraction operation would suffice for the decoupling of the substructure B from assembly AB: By placing the impedance of AB and B in block-diagonal form, with a minus sign for the impedance of B to account for the subtraction operation, the same equation that was used for primal coupling can now be used to perform the primal decoupling procedures. with: The primal disassembly can thus be understood as the assembly of structure AB with the negative impedance of substructure B. A limitation of the primal disassembly is that all DoF of the substructure that is to be decoupled have to be exactly represented in the assembled situation. For numerical decoupling situations this should not pose any problems, however for experimental cases this can be troublesome. A solution to this problem can be found in the dual disassembly. Dual disassembly Similar to the dual assembly, the dual disassembly approaches the decoupling problem using the admittance matrices. Decoupling in the dual domain means finding a force that ensures compatibility, yet acts in the opposite direction. This newly found force would then counteract the force that is applied to the assembly due to the dynamics of substructure B. Writing this out in equations of motion: In order to write the dynamics of both systems in one equation, using the LM-FBS assembly notation, the following matrices are defined: In order to enforce compatibility, a similar approach is used as for the assembly task. Defining a -matrix to enforce compatibility: Using this notation, the disassembly procedure can be performed using exactly the same equation as was used for the dual assembly: This means that coupling and decoupling procedures using LM-FBS require identical steps, the only difference being the manner in which the global admittance matrix is defined. Indeed, the substructures to couple appear with a plus sign, whereas decoupled structures carry a minus sign: More advanced decoupling techniques use the fact that internal points of substructure B appear in both the