Reverse Engineering Ant Neck Design

Overview

Ants can lift and carry extraordinarily heavy loads and the neck is the single joint that connects the load path from the thorax to the head. To accurately model the geometry of the neck region of a Formica exsectoides specimen, micro-computed tomography (CT) was used to obtain high resolution 3-dimensional data and was converted to a mesh for mechanical analysis. Unlike typical microscopy techniques, microCT captures internal features that would otherwise be difficult or impossible to obtain.

Characteristics:

  • Acquisition of microCT images of specimens
  • Generation of anatomically correct mesh of ant neck
  • FE-based simulation of load on the ant neck

Thanks to

Department of Mechanical and Aerospace Engineering, The Ohio State University: 
V. N. Nguyen • B.W. Lilly • C.E. Castro

Image Acquisition

To prepare for microCT imaging, specimens were fixed in alcoholic Bouin’s solution, stained with Iodine, transferred to ethanol, and dehydrated using HMDS. The dry specimens were fixed to the surface of a plastic plate using a low viscosity cyanoacrylate glue. The plate was then mounted to a sample holder using adhesive putty in a SkyScan 1172 microCT scanner. The X-Ray images were processed using SkyScan software into serial 2-dimensional slices.

Mesh and Model Generation

The serial 2-dimensional slices were imported into ScanIP (Simpleware Ltd. Exeter, UK). The exoskeleton and esophagus were segmented using built-in tools such as threshold flood fill, painting, and boolean operations on masked sections. The segmented structure was cropped to focus detail on the neck region and meshed using the built-in algorithm +FEGrid within the +FE module of ScanIP. The algorithm produced a combination of tetrahedral and hexahedral elements, totaling 6,594,672 elements and 648,489 nodes with an average in-out aspect ratio of 0.7248. The mesh, consisting of four different parts, was imported into Abaqus® for mechanical analysis.

Results

The mesh was imported into Abaqus® and was easily manipulated as a result of using the built-in material placeholders and node/mesh set definitions in +FE. The results of the 3-dimensional model show a series of complex folds within the neck membrane that account for large deformation under lower loads. The FE analysis also reveals a stress concentration at the material transition between the neck membrane and head exoskeleton that corresponds to the rupture location under high loads.