Computer assisted engineering software provides quickly-constructed virtual models that often pinpoint potential problems prior to physical construction. Design analysis comes in various flavors: finite-element analysis (FEA); integrated CAD; simulation analysis; thermal analysis; structural analysis; and mold-flow analysis. Computer-based FEA examines deflections and stresses inherent in a design by creating a mathematical model representing a simplified version of the physical object. Necessarily, this depends on assumptions about materials, geometry, displacements and loads. Integrated CAD approaches analysis from the inside out, although this demands an accurate model. If a modeling package lacks this capability, users need to purchase a full-price stand-alone package. Simulation is a growing trend, neatly sidestepping the time, expense, and tooling issues for actual models. Putting a design model through digital testing discloses what needs replacement or change as well as examines what-if scenarios. Objects that handle heat require thermal analysis software. Machines ranging from space shuttles to stoves to electronic devices need their hottest spots identified and anticipated. Structural analysis tests material strength, a crucial element when designing vehicles or office buildings. Mold-flow analysis takes a component, identifies its material and location, and the software will show where the flow lines and weld will be. Greater safety, lowered cost, swifter time to market, and improved reliability all come from design analysis software.