"has been experimental" is correct and usable in written English.
You can use it to describe something that has had the attribute of being experimental. For example: "The new cancer treatment has been experimental, but has had favorable results in some cases."
Much of this work has been experimental in nature; for examples see Sciencewise, the NCCPE, and Connected Communities.
The majority of previous research on CCN2 in MI has been experimental and on the cellular level.
Unjustifiably called obscene, his writing has been experimental, probing into social and psychological realities of Bengali life.
Furthermore, much of the research has been carried out has been experimental and carried out in non-ecologically valid settings (typically a laboratory).
By "tangible form" I mean simply that this research has been experimental rather than strictly theoretical, that it has entailed participation and action rather than detached observation of what others were about.
This could have been expected as there has been experimental evidence from previous works that type-2 fuzzy logic is better suited to model higher levels of uncertainty.
The result might have been experimental folderol, but Alameddine has a genius for the emotional hinges on which novels turn.
Recently, however, there have been experimental observations that contradict the above symmetry-based concept of magnetization reversal.
We've been experimental, weird and wonderful, and credible; now it's just doing something else – being a pop group," is how Ally describes it.
There have been experimental summer grass fields at Giants Stadium, where for 23 football seasons the playing surface has been artificial.
This incident is considered to have been experimental, and the bombs were described as "home-made, amateurish and relatively ineffective".
