A physics-informed neural network with built-in conservation laws for mechanical super-resolution *R. Dingreville (Sandia National Laboratories), V. Oommen (Brown University), A. Robertson (Sandia National Laboratories), D. Diaz (Carnegie Mellon University), C. Alleman (Sandia National Laboratories), Z. Zhang (Brown University), A. Rollett (Carnegie Mellon University), G. Karniadakis (Brown University)