Documents

    Finite Element Modeling (FEM)

    This section describes how to perform Finite Element Method (FEM) analysis of our PneuNet actuator using the Abaqus software suite. 

    Overview of model components

    • 2 materials:(because wo notice at structure,so material can be imprecise)
      • frame:   polyflex            density of 1200Kg/m³,a Young’s Modulus of 0.1 GPa and a Poisson’s ratio of 0.38
      • airbag:  PA+PE            ...
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    FEM for Load Capacity

    In this section, we are mainly concerned with the impact of groove depth and wall thickness on the load.

    3 loads:

    • Step-1: pressure and concentrated force
    • Step-2: a contrary concentrated force

    So, we can finally get the side of the airbag when fully Inflated, the arm can maintain the level of the load.

    Then wo can get the load moment which represents the load capacity of this structure.

    Cae...

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    Import Parts

    In this project, as mentioned in the Design section, we only consider the characteristics of the manipulator in x-y plane. And thanks to the structural property, we only analyze a slice of the frame (as shown below) instead of the whole structure, which can make the simulation much less computationally expensive.

    ...

    Read more about Import Parts

    Assign Properties

    In this page, we will show detailed procedures of assigning material properties for frame and airbags.

    Create Material: frame

    Firstly, we create a new material named 'Material-frame' for the frame. And set the following properties:

    • General > Density:
      • Density = 1.2e-9 Mg/mm³
    • Mechanical > Elasticity> Elastic:
      • Young’s Modulus = 100 MPa
      • Poisson’s ratio = 0.38
    ... Read more about Assign Properties

    Assemble

    In this page, we first create instances from the imported parts for 'frame' and 'air bag', move the air bag towards proper position, and then replicate airbags in each chamber of the manipulator frame.

    Create instance

    Instances are created from imported Parts named 'frame' and 'air bag' in page 'Part', and we select instance type as Dependent (mesh on part).

    ...

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    Create Steps

    In this page, we create two steps, 'Step-1' and 'Step-2' for load simulations. 'Step-1' is created with procedure type of Static, General.

     

    In the next window, turn on Nlgeom option in Basic panel.

    ... Read more about Create Steps

    Create Loads

    Create sets and surfaces

    Firstly, we create a new set named 'fixed-end', by clicking 'Tools > Set > Create' button.

     

    Continue and click on the faces (red) of the part that is going to be fixed.

    ... Read more about Create Loads

    Mesh

    Seed edges

    Firstly, select Part in upper right panel and choose 'frame'. Click Seed Edges (button with shaded background in the figure) and select all the edges.

    In the new window, we...

    Read more about Mesh

    FEM for flexibility

    In this section, we are mainly concerned with the impact of groove depth and wall thickness on the flexibility.

    Cae here

    Because all the operations have been introduced in the previous section, we will only show the difference.

    The following is our Assembly.

    ...

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    Fabrication

    This section contains detailed step-by-step instructions for making a HPN manipulator. As explained in previous sections, the HPN manipulator consists of two parts: the main body consisting of 5 segments of honeycomb structure which were designed with different parameters, and pneumatic networks containing a mass of air chambers arranged regularly. The two parts are fabricated separately and then assembled together.

    Process overview 

    ... Read more about Fabrication

    Honeycomb Structure

    As we discussed before, the whole manipulator consists five parts, in order to achieve a balance between flexibility and load bearing capacity, the frame of each part was designed with different parameters. This is a tutorial about the fabrication of a single segment. 

    Honeycomb structure was build with the technology of 3D-printing, The STL file for 3D-printing can be download here.

    ... Read more about Honeycomb Structure

    Step 3: Heat Sealing

    This page illustrates the main step in fabricating the pneumatic networks. In this step, the design scheme is implemented by heat sealing the marked points on the airbag column in last step. Notice that the sealer should be configured with a proper heat-up time in one press to ensure the quality of airbags produced.

    ...

    Read more about Step 3: Heat Sealing

    Step 4: Seal

    In this page we will finish the last step of making pneumatic networks: sealing.

    Prepare the following materials and tools: a heat-sealed airbag column, connectors, a tweezer, heat sealer and a hot glue gun.

    finial_1

    Below is the unsealed pneumatic network.

    ...

    Read more about Step 4: Seal

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