Have applied to, and been rejected from, a number of PhD positions; are they really so difficult to get?
As for the question in your title (which originally was: "Is it really that difficult finding a funded PHD position?") the answer is it depends on the field and the country. As an engineer, in countries with a well-developed industry, the job opportunities for graduates outside academia are good, thus diminishing the competition for PhD positions. This being said, a grad student is not just hired to lay bricks because there is a wall to be built. It represents a substantial investment for professors who will thus rather have no student than a not-so-good one.

To the point, previous experience in the specific field of the PhD study is almost never a requirement, so I doubt it's the limiting factor in your case. Your grades might be though, or your written english proficiency, but these are guesses.

I think your strategy might be inefficient. From your text it sounds like you sent a large number of applications and are waiting for someone to bite the bait. A personal interaction with people in the labs you are interested in would be a better approach, for example via an internship or a visit, if you can afford it.

So I would narrow it down to a few places where you really would like to work, gather the reasons why you like them, and start establishing a contact via email, say what you like about their approach or research topic and how you think you could fit in. They will then be able to let you know what is needed to be accepted in the graduate program (note that you will still have to comply to the department, university or graduate school requirements in order to be accepted).