Viscoelastic Beam Properties of a TRAC Boom
This tutorial shows how to calculate cross-sectional properties of the TRAC boom with given dimensions and material properties using SwiftComp 1.3 and Abaqus SwiftComp GUI.
Flattened height: 45 mm, Web height: 6mm, Subtended angle: 90 degree, Ply thickness: 0.058 mm,
Radius of the flange (curved part): 24.85 mm,
Layup: 45/-45. The layup sequence is along with the direction pointing to the center of flange(Blue arrow).
Material properties
The matrix properties are given by means of the Prony coefficients presented in the table below and following the formulation of Figure 1. In addition, we will consider that the matrix has a constant Poisson’s ratio equal to 0.33.
We will use a square pack 2D SG with fiber volume fraction equal to vf = 0.64.
Software Used
In this tutorial we will use Abaqus CAE with the Abaqus SwiftComp GUI plug-in. Abaqus CAE will be used to GUI to define the time-dependent material properties and to run the viscoelastic homogenization. SwiftComp will run in the background.
Solution Procedure
The steps required to compute the effective viscoelastic properties using Abaqus SwiftComp GUI are as follows.
# Step 1. We define the material properties in global coordinate system. We click on Materials in Abaqus CAE and define the Fiber properties by means of the engineering constants and click “Ok”.
# Step 2. Within the Materials of Abaqus CAE, we create a dummy material called “Matrix”. Please note that we will not define the Prony coefficients of the resin using the Abaqus SwiftComp GUI in the next step.
# Step 3. In the Abaqus SwiftComp GUI menu, we click on Input Time-Dependent Properties. We select “Prony Coefficients” and “Viscoelastic” in the Method & Analysis section. We pick “Matrix” as the Material to be modified in the drop down menu. Then, we input the relaxed Young modulus, Poisson’s ratio and the Prony coefficients following the equation presented above. Finally, we click “Ok”.
# Step 4. From the default the Abaqus SwiftComp GUI SGs, we pick the 2D Structure Genome with Square pack. We input the fiber volume fraction, define the approximate global mesh size, and click “Ok”. A square pack microstructure will be automatically generated.
# Step 5. Now, we will compute the effective viscoelastic properties. To do so, we click on Homogenization and select Viscoelastic in Analysis Type. In the Viscoelastic/Thermoviscoelastic Analysis section, we define the range of the time (i.e. Initial time” and Final time”) in which we want to output the effective properties as well as the frequency (i.e. Time increment” defined in decades).
# Step 6. We click on Ok to run the homogenization step. SwiftComp on the background will run the homogenization.
# Step 7.The results can be found in the .sc.k file as shown next. Note that the effective properties will be outputted for each specified time.
# Step 8.We move on to macroscopic homogenization of the trac boom.
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# Step 8.We move on to macroscopic homogenization of the trac boom.
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# Step 9.’Create the part geometry for the TRAC Boom. Use Set sketch plane for customized SG (Pointed by the Black arrow) -> Use create planar shell -> Select the plane and vertical axis -> Sketch half of the base line (Highlighted as a red line). Its geometry is a straight line (Web height) from (0,10) to (0,0) and a curved line (Flange) from (0,0) to (25,-25) centered at (25,0). Set its thickness to 0.2 mm to the right of the baseline and partition the flanges 9 times at 10° to obtain a smooth curve. Partition the part in the middle to obtain two plies off thickness 0.1 mm each. Mirror the part about the vertical to get the geometry of the TRAC Boom.
# Step 10.To enter the material properties for the part, first we need to manually calculate the material properties for both the plies one with orientation 45° and the other with orientation -45°. Choose the material properties from the results of the computed effective viscoelastic properties in the previous section for the appropriate time interval(As required) .Use the formula C’=Rsigma*C*(Rsigma)Transpose to obtain the rotated properties. Now we proceed to enter the properties of the part as follows. Go to Property -> Create material -> Mechanical -> Elasticity -> Elastic -> choose in Type Engineering constants and add the material properties for one of the plies. Repeat the steps for the other ply. Now create two shell homogeneous sections, each one corresponding to one of the materials using the create section option. Now assign the material properties using the assign section option as follows. Select the plies corresponding to the material to select the appropriate section after choosing done.
# Step 11. Module > Mesh > Seed Part and choose mesh size, then Click ‘Mesh Part’
# Step 12. Homogenize the part to get the final results.
References
- Liu, X.; Tang, T.; Yu, W., Pipes, R. B.: “Multiscale modeling of viscoelastic behavior of textile composites,” International Journal of Engineering Science, Vol 130, September 2018, pp. 175-186, DOI: 10.1016/j.ijengsci.2018.06.003.
- Rique, O.; Liu, X.; Yu, W., Pipes, R. B.: “Constitutive modeling for time- and temperature-dependent behavior of composites,” Composites Part B: Engineering, Vol 184, March 2020, DOI: 10.1016/j.compositesb.2019.107726.