Acceleration of OpenGL
The implementation of rendering software in hardware which speeds up
rendering because the CPU will have to do less. OpenGL has been designed for
hardware acceleration but its functionality can also be entirely implemented
The reinforcement permeability varies depending on the direction in which
the resin flows. This is typically caused by the geometry of the fabric, and
useful in applications where high strength is required in a specific
A virtual connection between two points that acts like a tube with no
volume and no resistance. Can be defined in RTM-Worx using the RTM runner
with a high fibre/volume fraction (say 99%) and low permeability (1000 times
as low as adjacent surfaces).
Used in two contexts: (1) the pane at the left side of the RTM-Worx window
and (2) the Windows Control panel where you can change settings of your
Control Volume Method (CVM)
A method to divide a large and complex product into small volumes to which
conservation laws (mass, momentum, energy) are applied to obtain a set of
equations that describe the flow and can be solved numerically.
In RTM-Worx a curve is a line that connects several keypoints. It can have
a diameter (runner) and optionally porosity and permeability (RTM runner).
Curves are used to define surface boundaries.
A method where a plane parallel to the computer screen is used to cut away
anything in between the viewer and this plane. This allows you to look inside
A file format designed by AutoDesk to exchange CAD models between
applications and used in AutoCAD™. DXF is an acronym for Drawing
easy flow path
A channel that is formed in between a rigid mould wall and the
reinforcement. When the permeability of the reinforcement is low, the
resistance of such a channel can be orders of magnitude smaller than the
resistance to flow in the reinforcement.
Injection of the resin along an edge of the mould. In practice typically
achieved by making a channel along the edge with a restriction to the
Smallest entity in which the model is subdivided for the calculation of
flow of the resin through the reinforcement (or volumes). Runners are
subdivided in line or runner elements, which are straight tubes with two
vertices. Surfaces are subdivided into triangles with three vertices. The
pressure gradient is constant on an element. Using more and smaller elements
increases the accuracy of the calculation, but also the calculation time.
Fraction of the volume that is occupied by the reinforcement. Equal to (1
Finite Difference Method (FDM)
An alternative method to discretize the partial differential equations
that describe conservation of mass, momentum and energy. The advantage of the
FDM is that it is easy to implement, but it is generally limited to
rectangular geometry which cannot be multiply connected (e.g. no ribs or
stiffeners). It has therefore been used a lot in scientific environments.
Finite Element Method (FEM)
This is the method used in RTM-Worx to discretize the partial differential
equations that describe conservation of mass, momentum and energy into a
linearised set of equations that can be solved numerically. The geometry is
subdivided into smaller objects, so-called elements, in which the resin
velocity is constant and pressure varies linearly.
Subdivision of a surface into triangular elements, where the size of the
elements varies gradually from very small to large and vice versa. Graded
meshes offer the advantage of the ability to use small elements in the
neighbourhood of details in the geometry while the overall number of elements
can be limited by using larger elements where possible.
Tiny image that is used to indicate file types, programs and button
Calculation in which it is assumed that the temperature differences are
too small to affect the flow kinetics. Without the need to calculate
temperatures and reaction kinetics, the calculation can be very fast, and few
material data is needed. For RTM and Vacuum Injection, the isothermal
calculation delivers a lot of results at very low cost.
Reinforcement that has a resistance to flow of resin that is equal in all
directions. An example is a random mat, and several square weaves (but not
all of them, the 45 degree direction can differ from weft and warp, even when
weft and warp are identical!).
The representation of a location in space (with x, y and z coordinates),
used in RTM-Worx for the vertices of curves. Keypoints can be assigned
properties to turn them into venting or injection ports.
A Finite Element on a curve or runner.
The subdivision of the model geometry into elements. Curves and runners
are subdivided into line elements, surfaces are subdivided into
The complete, but simplified, description of the RTM-process for a
product, which includes the geometry, reinforcement properties and resin
Logical division of an computer program into different tasks that run
asynchronously. Synchronisation of - and communication between threads adds
little overhead, because threads are part of the same process. A
well-designed multithreaded application utilises resources (most notably the
CPU) more efficiently. For example: RTM-Worx uses a separate thread to render
the plot of the model. This thread has a slightly lower priority compared to
the main thread that handles user input, which keeps RTM-Worx responsive,
even when almost 100% of the CPU capacity is used to draw the model.
nodal Control Volume
The FEM nodes all have a volume associated with them that is composed out
of parts of the elements the node is connected to. The flow front is tracked
by monitoring the filled fraction of each nodal Control Volume.
Vertices of elements that define the position of the element in 3D space;
e.g. a node has x, y and z coordinates. In RTM-Worx, pressures are calculated
at the nodes which defines the pressure gradient and resin velocity in each
A library of subroutines, designed by Silicon Graphics Inc. (SGI), to
render 3D realistic images. This library shields application programs from
the actual implementation, which can be either in hardware (fast but
expensive), or in software (slow but cheap). OpenGL is available on a lot of
platforms, including Unix™, Linux, Mac OS™, OS/2™ and
Microsoft Windows™. OpenGL has been used a lot in the scientific
community, but gains more and more acceptance in the gaming industry (most
notably DOOM) which in turn boosts the development of cheap hardware that
A measure of the resistance of a porous medium to the flow of fluids.
Permeability is a reinforcement property, independent of the resin.
Fraction of the total mould volume that can be occupied by the resin. It
is related to the fibre/volume fraction Vf as: porosity = 1 - Vf.
The calculations and user actions to view results of the simulation
graphically in order to interpret what happened in the mould. See also
Actions to be taken before the simulation can be done. Includes entering
the geometry, reinforcement and resin properties, and verifying the
correctness of the model. The term originates from the classical
batch-oriented FEM applications where you had to put all the data in an ASCII
file which was then submitted to the FEM application which would read the
input file, do a lot of number crunching and produced a lot of output files.
In the course of time, specific applications were developed to be able to
build the input file interactively (called a pre-processor) or to view the
results graphically (called a postprocessor). RTM-Worx integrates all this
functionality in one application and a single interface.
Random Access Memory. Your computer needs kind of memory to (temporarily)
store application code and data, because the CPU can only execute
instructions and fetch/store data that is available in RAM. The contents of
RAM are lost when you turn off your computer. RTM-Worx stores the complete
model and the simulation results from a single calculation step in RAM. The
amount of RAM used by RTM-Worx depends on the complexity of the model and the
number of nodes and elements in the mesh.
For the RTM-Worx license, you need to register your copy of RTM-Worx after
installing it on your system. Because licenses are sold on a per-machine
basis, you need to register separately for each computer you want to run
RTM-Worx on. RTM-Worx generates a Site Code that is specific to the
installation and computer it runs on. You contact us with the Site Code to
acquire an accompanying Registration code. This registration code has to be
entered in the dialog that also specifies the Site Code. RTM-Worx will run
when the Registration code matches with the Site Code until the license
expiry date has passed.
A curve with a diameter is called a runner and can be used to model tubes
(resin delivery) and easy flow paths. The flow in a runner is always assumed
to be in the length direction.
A triangular element suitable to model resin flow in a thin-walled section
of your product. Locally, the flow is treated two dimensionally. It is
assumed that the flow in the third direction, perpendicular to the triangle
is negligible compared to the in-plane flow.
Same as a shortcut. See below.
Introduced with the Windows 95 interface, and also incorporated in Windows
NT 4.0, shortcuts are small files that serve as an alias to a file stored
elsewhere (like links under Unix). Shortcuts are used for the icons on your
desktop and the entries in the Start menu, but you can also create and store
shortcuts in any directory on your harddisk. Actually, the Desktop and Start
menu are directories too.
A file format defined by SLA (for interfacing CAD programs with
Stereolithografy equipment) that describes the geometry of an object in 3D
space by a list of triangles (no more, no less). RTM-Worx is able to read
both the ASCII and binary STL file formats. Most CAD applications can write
those files because their structure is so simple. However, the geometry is
stored quite inaccurately (single precision) and small details or rounded
corners will result in a lot of extremely stretched triangles. We recommended
you to remove all details, rounding etc. before generating an STL file to
transfer the model to RTM-Worx.
Surfaces are used to model thin-walled sections of the product geometry. A
surface is a flat or curved plane in space defined by a loop of boundary
curves in between keypoints that will also be on the surface boundary. You
can assign thickness and reinforcement properties to surfaces to turn them
A number, assigned as a property of keypoints, curves or surfaces that can
be used to quickly select a set of objects with identical properties.
Typically used when RTM-Worx imports a FEM model that uses so-called Element
Groups to assign properties. The element group number is assigned as the tag
A rectangular window located below the menu or above the status line with
buttons and edit fields that provide quick and easy access to the
functionality of RTM-Worx.
A small window with a terse description of a button, edit field or other
control. It pops up if the mouse cursor is on top of the control (like when
you are hesitating because you are trying to think of what it does), but
stays away when you move quickly (you know what you are doing and don't
need any help). RTM-Worx also uses the ToolTips to display error conditions,
valid ranges for numerical input and results of expressions.