The phrase "a heavy thud" is a correct and usable part of a sentence in written English.
You can use it to describe a loud, solid sound. For example: "I heard a heavy thud coming from behind the door."
Christmas credit card bills drop with a heavy thud through the letterbox.
Eventually, there was a heavy thud, followed by the voices of guards calling for medical help.
It fell with a heavy thud, like one of those poor geese, shortly after the play began.
They ran hard around the course, thundering around turns, leaping over gates and landing with a heavy thud in explosions of sand.
I slipped on a patch of clear ice, both legs flew up and I landed with a heavy thud on my backside.
The silence was broken only by the click of their heels and the occasional crack of outgoing mortar shells followed by a heavy thud as they landed in rebel neighborhoods.
Some were dressed in military fatigues and had heavy anti-aircraft guns; they, too, fired joyously as they passed cheering crowds, with a heavy thud-thud that shook the ground.
Mobile AR had a lot of hype heading into the rollout of ARKit and ARCore this past year, but for the most part mobile AR apps have delivered a pretty heavy thud, failing to deliver on their futuristic promises.
Nuku Hiva view And killer coconuts, too: suddenly there's a hugely heavy thud.
My birthday fell, and still falls, for that matter, though with an increasingly heavy thud, on 8 December, and in those far-off days that date was a public holiday in Catholic Ireland, being the Feast of the Immaculate Conception – yes, I know, I know – and the day when country folk flocked to the capital to do their Christmas shopping.
The police charged this horde at Bleecker Street, led by a grizzled old sergeant swinging his truncheon; one observer noted that for a while, "nothing was heard but the heavy thud of clubs falling on human skulls".
