"fierce experience" is correct and usable in written English.
You can use it when talking about a difficult or intense experience, either physical or emotional. For example: "I never imagined I could face such a fierce experience as mountain climbing."
Bonds form fast in hospitals: Families see each other's pain and fear, and they understand it, from fierce firsthand experience.
"While SBC has been known as a well-managed company and a fierce competitor, recent experience in Illinois raises the prospect that SBC may now be recognized only as a fierce competitor," he said.
The authors suggest "competition by design" proved only effective in cases of low (perceived) competition which implies that when teams experience fierce instead of mild competition, benefits for creative performance will not be realized.
Tel Tamr, a town near the Assyrian Christian villages where the abductions occurred, has experienced fierce fighting between Isis militants and the Kurdish YPG militia, according to the SOHR.
The spike in attacks is a worry for the government of southeast Asia's second biggest economy, which is also experiencing fierce, sometimes violent rivalries among political factions.
In the eastern city of Ajdabiya, which had experienced fierce fighting last week as Qaddafi forces advanced on the city, there was sporadic shelling in the morning and in the afternoon, by the city's western gate.
Meanwhile, the Sunni community's militias were challenged by militias organized by Islamic fundamentalist groups, and the Shīʿite community experienced fierce divisions between the more clerical Hezbollah in the south and the more secular Amal ("Hope," also an acronym for Afwāj al-Muqāwamah al-Lubnāniyyah [Lebanese Resistance Detachments]) movement led by Nabbih Berri.
The automotive component manufacturing sector is experiencing fierce competitions.
The manufacturing industries are now experiencing fierce pressure of competition from every corner on this planet.
Millen experienced fierce criticism from both the press and parliament during his time as Minister for Repatriation, but he is remembered as an important figure in Australia's war effort and subsequent recovery.
