MSC Software Corporation today announced that researchers at the Laboratoire d'Astrophysique de Marseille (one of the public institute in astrophysics of the French National Center for Scientific Research) are using MSC Software's Marc Nonlinear FEA software to simulate a new process that involves the use of hydroforming to reach extreme optical mirror shapes, necessary for the next generation of astronomical telescopes and instruments, and to reduce the cost and lead time of producing freeform mirrors.
"We selected Marc to analyze the hydroforming process because the software has demonstrated the ability to provide accurate results in problems involving complex nonlinear changes in geometry and materials properties," said Zalpha Challita, in post-doctoral position at CNRS-LAM. "Marc demonstrated the ability to accurately model the hydroforming process and will be used extensively going forward."
Freeform mirror surfaces - surfaces with a shape more complex than a symmetrical conventional mirror surface (as for example, sphere, parabola, hyperbola, etc.) -- offer substantial benefits by providing additional degrees of freedom that make it possible to improve the optical performances of the instrument, reducing the overall instrument mass and size. The hydroforming technique deforms the material to its final form, thanks to the contact with a specific mold shape, in a single step by applying a fluid at high pressure on the optical surface. This method also has the potential to produce a higher quality surface because it eliminates the need for a mechanical tool to contact the mirror surface.
The hydroforming process is difficult to design and optimize because the mirror undergoes plastic deformation to provide a freeform optical surface. Finite Element Analysis (FEA) was performed with Marc to quantify the residual errors after the hydroforming process and to optimize the system. The capabilities of Marc in fine tuning optimization allow it to match the experimental results according to the error budget of a few micrometers authorized in astronomical optics.
