Introduction to MotionSolve

MotionSolve is a multi-body solver available in Altair Simulation.

The term multi-body represents complex systems encountered in industries such as transportation (automobiles, buses, trucks, trains, and planes), industrial machinery (textile, packaging, and manufacturing), aerospace systems (spacecraft and missiles), consumer goods (washing machines and watches), and electro-mechanical systems (printers and copiers).

A defining characteristic of all these systems is that they can undergo large overall motion that is comparable to their dimensions. These systems are typically represented as a set of connected particles, rigid bodies, and flexible bodies that are subjected to a variety of environmental forces and inputs. The multi-body dynamics (MBD) methodology represents a very good trade-off between mathematical complexity and accuracy, and MBD methods have been successfully used to describe the real-world behavior of many systems. MBD models are mathematically described by second order, index-3, and differential-algebraic equations.

While the underlying physical principles of MBD have been known since Isaac Newton, the equations for even relatively simple systems cannot be manually derived or solved. With the advent of powerful digital computers and new numerical analysis methods developed in the last forty years, it is now feasible to calculate the response of such systems from first principles and obtain insight into their performance.

MBD is a systematic approach for understanding and improving the overall performance of such systems. This methodology consists of four key steps:
  • Accurate mathematical modeling of systems, subsystems and their components.
  • Automatically formulating and assembling the governing equations for a system using the laws of physics and the principles of mechanics and solving the system equations on a digital computer with numerical methods.
  • Understanding system behavior by examining the computed response.
  • Improving system performance using optimization techniques or controlling system behavior using mechatronic and control systems.