Dialog: Material Data
<IMG SRC="pics/DialogMaterialData_1.gif" WIDTH="472"
HEIGHT="331" VSPACE="0" HSPACE="0" ALT="">
In this subdialog you can enter, edit or view the material data for the highlighted
layer.
Version notice: entering and editing material data is
only available in WUFI Pro.
For a detailed discussion of the material data, please consult the
<A HREF="MaterialData.htm">reference: Material Data</A>.
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"Layer/Material Name":
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The name of the current material, as defined in the
<A HREF="DialogAssembly.htm">assembly</A>. Use the drop-down list to switch
between the materials of the current assembly without closing and reopening
this dialog.
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"Basic Values"
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"Bulk Density [kg/m³]",
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"Porosity [m³/m³]",
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"Specific Heat Capacity, Dry [J/kgK]",
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"Thermal Conductivity Dry [W/mK]",
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"Water Vapor Diffusion Resistance Factor [-]":
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These <A HREF="BasicMaterialData.htm">basic material data</A> are
required as a minimum for a calculation.
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"Optional Parameters": |
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Some of the material data in the following section "Optional Data"
are difficult to acquire, but WUFI offers means to
<A HREF="Glossary.htm#approximate">approximate</A> or
<A HREF="glossary.htm#generate">generate</A> them from standard data which
can be collected more easily. These standard data are then "Optional
Parameters" which may be required, depending on the settings in the
"Optional Data" dialog.
The optional parameters are discussed in the respective topics of the
following section:
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"Optional Data":
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Enter the optional material data in these
<A HREF="Glossary.htm#table">tables</A> (if required).
The optional material data comprise the moisture storage function of the
material, the liquid transport coefficients, the moisture-dependent thermal
conductivity and the moisture-dependent vapor diffusion resistance factor.
The optional data are always entered in <A HREF="Glossary.htm#table">tables</A>.
However, you can have WUFI automatically create some of these tables by entering
other related data from which the tables can be generated.
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"Moisture Storage Function":
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Enter the <A HREF="MoistureStorageFunction.htm">moisture storage function</A>
of the material, i.e. the moisture contents [kg/m³] which result
from exposition to air with various relative humidities (0..1).
If detailed tabulated data are not available, but the moisture retention
function of the material can be adequately described by an
<A HREF="MoistureStorageFunction.htm">approximation function</A>, you can
check the option "Approximate" and enter
- the sorption moisture corresponding to 0.8 RH, w80
("Reference Water Content [kg/m³]", nowadays
determined according to German standard DIN 52620) and
- the "Free Water Saturation [kg/m³]"
wf
in the additional table "Optional Parameters". WUFI
then uses an
<A HREF="MoistureStorageFunction.htm">analytical moisture storage function</A>
which passes through these two points and zero.
For non-hygroscopic materials, just leave the table of the moisture storage
function empty. For numerical reasons, however, WUFI needs a defined
moisture storage function; it then internally uses a
<A HREF="MoistureStorageFunction.htm">default function</A> which allows
for the very low sorption moisture of non-hygroscopic materials.
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"Liquid Transport Coefficient - Suction"
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"Liquid Transport Coefficient - Redistribution":
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Enter the
<A HREF="LiquidTransportCoefficients.htm">liquid transport coefficients</A>
in this table - separately for suction and redistribution.
If the liquid transport coefficients for the material at hand are not
known, you can have WUFI automatically
<A HREF="Glossary.htm#generate">generate</A> a table by estimating
the coefficients from the
<A HREF="LiquidTransportCoefficients.htm">water absorption coefficient
(A-value)</A> which is known for most materials or at least easily
measurable.
To this end, check the option "Generate" and enter the
A-value in the additional table "Optional Parameters"
(in [kg/m²Ös]; the relevant German
standard uses the non-SI units [kg/m²Öh].
Division by 60 converts such values to SI). WUFI automatically
generates a three-line table with the corresponding estimated liquid
transport coefficients.
Please note that only a rough estimate is possible which proves successful
in many cases, but which is not necessarily useful for all materials.
Especially, there may be inaccuracies in the shape of the suction
profiles. Generating is just meant to be some assistance; you should
not blindly rely on it. Future WUFI versions are planned to offer more
sophisticated methods.
Remarks on generating:
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The <A HREF="LiquidTransportCoefficients.htm">estimate</A>
of the liquid transport coefficients from the A-value also uses
the moisture contents
<A HREF="MoistureStorageFunction.htm">w80 and
wf</A>. If the moisture storage function is being
approximated from w80 and wf (see
above), the two values are directly taken from these two entries;
otherwise they are calculated from the corresponding table - by
interpolation, if necessary.
If no moisture storage function has been defined as yet,
generating is not possible - the table remains empty (but you
can already enter the A-value).
If the moisture storage function is modified after generating,
the generated table adapts automatically. Please note, therefore,
that modification of a material property can also change another
property as a side effect without this being immediately
evident.
If you want to generate both the tables for suction and those for
redistribution, both must of course be derived from the same
A-value - the two tables therefore share this text box in the
"optional Parameters". Note that here, too, a
modification of the A-value intended to change one coefficient
may entail changes in the other one (if you are generating only
one of the tables and editing the other one by hand, the
non-generated table is not affected by a modification of the
water absorption factor, of course).
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"Thermal Conductivity, Moisture-dependent": |
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Enter the <A HREF="ThermalConductivityMoistureDependent.htm">heat
conductivity</A> of the material as a function of its moisture content
if you want to allow for this dependence.
If you are satisfied with a simple linear dependence of the heat
conductivity on the moisture content, you can have WUFI automatically
<A HREF="Glossary.htm#generate">generate</A> a two-line table by entering
the <A HREF="ThermalConductivityMoistureDependent.htm">moisture-induced
heat conductivity supplement</A>.
To this end, check the option "Generate" and enter the
supplement in the additional table "Optional Parameters"
(in [%/m-%]). WUFI automatically generates a two-line table with the heat
conductivities resulting for the dry condition and the maximum water
content. Heat conductivities for intermediate moisture contents are
linearly interpolated during the calculation.
Remarks on Generating:
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The <A HREF="ThermalConductivityMoistureDependent.htm">evaluation</A>
of the heat conductivity for maximum water content also uses the
basic material properties
<A HREF="BasicMaterialData.htm#bulkdensity">bulk density</A>,
<A HREF="BasicMaterialData.htm#porosity">porosity</A>
and <A HREF="BasicMaterialData.htm#heatconductivity">heat
conductivity dry</A>. If these values are modified after generating,
the generated table adapts automatically. Please note, therefore,
that modification of a material property can also change another
property as a side effect without this being immediately
evident.
If the required basic material data have not all been defined as
yet, generating is not possible - the table remains empty (but you
can already enter the supplement).
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"Water Vapor Diffusion Resistance Factor,
Moisture-dependent":
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Enter the <A HREF="WaterVaporDiffusion.htm">diffusion resistance factor</A>
of the material as a function of moisture content if you want to allow
for this dependence.
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General remarks on
<A HREF="Glossary.htm#approximate">approximating</A> and
<A HREF="Glossary.htm#generate">generating</A>:
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For all optional material properties - except the diffusion resistance
factor - WUFI is holding two tables in memory: one table created by
hand (editable), and one generated table (non-editable). You can work
on both tables in parallel; which of both is used for the calculation
depends on whether the option "Approximate" or
"Generate" is activated at the start of the calculation,
or not.
By activating or deactivating the option, you can switch between the
two kinds of tables. The unused table remains inactive in background.
You can use the "Copy" button to copy the generated
table line by line to the editable table and work on it there by hand.
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"Color":
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Select the color of the material for the
<A HREF="DialogAssembly.htm">graphical assembly display</A>.
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"Typical Built-In Moisture [kg/m³]":
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A typical application for WUFI is a calculation to determine the time it takes
a newly-built wall to dry out. If a typical initial moisture content for the
current material is known, you can enter it here. Assigning the initial
moisture contents to the individual layers then only takes one click on a button
in the
<A HREF="DialogInitialConditions.htm">"Initial Conditions" dialog</A>.
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"Layer Thickn. [m]":
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A quick way to edit the layer thickness without going back to
the <A HREF="DialogAssembly.htm">assembly editor</A>.
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"Paste into Material Database":
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Opens the
<A HREF="DialogDatabaseMaterialsNew.htm">"New Material" dialog</A>
of the <A HREF="DialogDatabaseMaterials.htm">material database</A> which allows
you to write the current material data to the
material database for quick and easy use in other assemblies.
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