Tips & Tricks

Why do total mass, sum of part masses and sum of nodal masses not match ?

This tip discusses the possible discrepancies in informations concerning total mass, part masses, nodal and element masses, given in the Virtual Performance Solution (VPS) output listing.

Which moments of inertia to use in added mass (MASS / ) cards ?

This tip discusses the choice of physically meaningful numbers to be used, when moments of inertia need to be specified in an added mass definition.

Some possible problems with CNTAC or TIED definitions

This tip discusses some of the reasons that might be responsible for problems with contact or tied definitions in a VPS simulation

Relation between Bulk Modulus K, Shear Modulus G, Young's Modulus E and Poisson's ratio ν

This tip explains the relations between the parameters that describe the linear elastic behavior of materials

How to convert force-deflection into true stress-strain curves?

This tip helps to convert typical tensile test data into stress-strain curves to be used in many material models of Virtual Performance Solution (VPS)

Process optimization: the future of numerical simulation software

Optimization is becoming a very popular word. However, what does it mean and what does it involve? The goal of this e-tip is to give some keys about optimization concepts and its use in process optimization. In a first stage, we will describe the type of optimization problems that could be solved and in a second stage, the principles and algorithms will be presented. Finally, advantages and drawbacks of the different methods and algorithms will be addressed, with respect to the different types of optimization problems which can be solved.

Casting simulation: from prototype to performance

Passenger safety in cars, planes and other transportation vehicles is an ethical obligation, a legal issue and a technological challenge. Simulation is a well implemented tool in order to test the behaviour of a car body during crash. The models, including rapid deformation and rupture, are sophisticated and reliable. Currently, most properties used in such simulations correspond to homogenous and defect free materials. However, cars are manufactured before being crashed. And manufacturing routes such as casting, but also stamping, forging or welding, do not provide defect free and homogeneous materials.

Parallel processing

“To pull a bigger wagon, it is easier to add more horses than to grow a gigantic horse.” This paraphrased quotation nicely expresses the basic concept of parallel processing. The speed of sequential computers has been doubling every eighteen months, according to Moore’s law. However, at any given time, that speed is limited by the state of the art in integrated circuit design and manufacturing. To circumvent that limitation, it is possible to split a given computationally intensive task among multiple processors working simultaneously.

The manufacturing of sand cores

The manufacturing of iron, steel and non-ferrous castings is achieved using a variety of casting process designs, and most of these involve the use of sand cores which form the internal shape of the casting. A good quality casting requires a good quality core. Dimensional stability, uniform density, strength, hardness and permeability are some of the characteristics that need to be controlled. A good core must have suffi cient strength and hardness to be handled and to resist during the pouring of liquid metal. Suffi cient permeability is also necessary for the escape of gases generated during the casting process. The diff erent manufacturing processes and some of the issues related to core production will be discussed here.

Critical issues in modelling investment casting

Reduce part development lead-times by a better knowledge of process and an early confi rmation of metallurgical capabilities is one of the main topics for investment casting technology. Numerical simulation is one of the major tools which can be used to face this goal. This e-tip illustrates a simulation methodology usable to optimize a casting design in an effi cient and rapid way.