This work presents a new technique yielding computable bounds of quantities of
interest in the framework of linear visco-elastodynamics. A novel expression for the error representation
is introduced, alternative to the previous ones using the Cauchy-Schwarz inequality.
The proposed formulation utilizes symmetrized forms of the error equations to derive error
bounds in terms of energy error measures. The practical implementation of the method is based
on constructing admissible fields for both the original problem and the adjoint problem associated
with the quantity of interest. Here, the flux-free technique is considered to compute the
admissible stress fields. The proposed methodology yields estimates with better quality than the
ones based on the Cauchy-Schwarz inequality. In the studied examples the bound gaps obtained
are approximately halved, that is the estimated intervals of confidence are reduced.Peer ReviewedPostprint (published version