Is there an English word for the Japanese オブジェ?

_{(Posting comment as answer on request.)}

The term objet d'art is sometimes used to describe works of art, and is used especially for modern sculptures and other "objects", as you want. It comes from French, and since the Japanese word you're asking about also comes from the French word objet, this may be appropriate.

See Wiktionary, Merriam-Webster ("The house is decorated with objets d'art from around the world"), About.com's Art History Glossary, Dictionary.com, or, especially, the Google Image Searches for オブジェ versus objet d'art.

I'm not sure if this is too specific, but installation may be the equivalent English language word.

I would just use the French word objet. (In English, that would have a slight mocking tone, which I regard as a plus.)

If asked for a term to describe the results in the linked Google image search, I'd be inclined to say abstract sculpture.

Installations refer to a variety of art exhibits that are installed in a gallery space or elsewhere; they aren't specific to sculpture.

Similarly, objet d'art essentially just means work of art; an elaborately made book, spoon or car could be an objet d'art but would not, I think, fall under the category OP is trying to describe.