3D CAD Model Creation in Autodesk Inventor

# Autodesk Inventor CAD Modeling Project — Auxetic Metamaterial Structures

## Project Overview
I am a college student and need an experienced CAD designer to create 3D models of the five structures shown in **Figure 1 (a–e), page 3** of my attached research paper, titled *Multi-objective design of tetra-chiral re-entrant auxetic metamaterials for energy absorption in engineering structures*.

The models must closely match the shapes, geometry, and cell arrangements shown in the paper. Please do not create generic honeycomb patterns or simple rows of hourglass shapes.

## Required Designs

1. **Figure (a) — CRS Unit Cell:** A single hollow, hourglass-shaped re-entrant cell with inclined ribs and a defined wall thickness.
2. **Figure (b) — Chiral Core:** A central circular hub connected to four angled arms.
3. **Figure (c) — TREAM Unit Cell:** A combination of the re-entrant cell and central chiral hub with connecting arms.
4. **Figure (d) — CRS Array:** Multiple re-entrant cells arranged in staggered, interlocking rows, matching the arrangement in the paper.
5. **Figure (e) — TREAM Array:** A periodic array combining re-entrant cells and chiral cores, matching the paper's pattern.

## Dimensions and Technical Requirements

The paper gives the following nominal dimensions:
- Individual cell width, **w = 60 mm**
- Individual cell height, **h = 38 mm**
- Overall array width, **W = 253.48 mm**
- Overall array height, **H = 184.84 mm**

Some parameters, including rib thickness, re-entrant angle, chiral hub radius, arm geometry, and extrusion depth, are not fully specified in the figure. Please review the paper and use reasonable engineering assumptions for any missing values. Clearly document all assumed dimensions.

## Deliverables
- Five editable Autodesk Inventor part files (`.ipt`), or equivalent editable CAD models.
- An Autodesk Inventor assembly (`.iam`) if appropriate.
- Neutral STEP files (`.step` or `.stp`) for all five designs.
- Engineering drawings with dimensions, preferably PDF and Inventor drawing files (`.idw` or `.dwg`).
- Screenshots showing the completed models and their similarity to Figure 1 in the paper.