Problem digesting sample for Ti analysis using ICP-OES
If you want to stay with a sulfuric acid type of digestion, there is this(1) paper that describes a microwave digestion using copper(II) and hydrogen peroxide to facilitate the digestion.  

From my personal experience, if your lab is properly equiped, my first choice would be an $\ce{HF}$ digestion or a nitric/perchloric acid digestion.

1)"A rapid and simple microwave-assisted digestion procedure for
spectrophotometric determination of titanium dioxide
photocatalyst on activated carbon", ScienceDirect, Talanta 71 (2007) 1867–1872