"力学模型" can be translated into English as "mechanical model" or "mechanics model".
"Mechanical model" is more commonly used and directly refers to a model representing mechanical systems or phenomena.
"Mechanics model" is also acceptable, though slightly less common, and emphasizes the aspect of mechanics (the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements).
In most contexts, especially in engineering and physics, "mechanical model" would be the preferred choice.