Mechanical properties of tracheal tubes in the American cockroach (Periplaneta americana)

Abstract

Insects breathe using an extensive network of flexible air-filled tubes. In some species, the rapid collapse and reinflation of these tubes is used to drive convective airflow, a system that may have bio-inspired engineering applications. The mechanical behavior of these tracheal tubes is critical to understanding how they function in this deformation process. Here, we performed quasi-static tensile tests on ring sections of the main thoracic tracheal trunks from the American cockroach (Periplaneta americana) to determine the tracheal mechanical properties in the radial direction. The experimental findings indicate that the stress-strain relationships of these tracheal tubes exhibit some nonlinearities. The elastic modulus of the linear region of the stress-strain curves tubes was found to be 1660 ± 512 MPa. The ultimate tensile strength, ultimate strain and toughness were found to be 23.7 ± 7.33 MPa, 2.0 ± 0.7% and 0.207 ± 0.153 MJ m −3 , respectively. This study is the first experimental quantification of insect tracheal tissue, and represents a necessary step toward understanding the mechanical role of tracheal tubes in insect respiration.

Dynamics of tracheal compression in the horned passalus beetle

“…The observation that tracheal compression is slower than reinflation is consistent with the idea that elastic energy is stored in the tracheal wall during compression, and reinflation occurs as a passive process of energy return, with dynamics governed by the viscoelastic properties of the trachea (39). Variation in structural properties of the tracheae, including thickness, second-moment of area, and taenidia geometry, might play functional roles in storing and releasing energy during cycles of compression and reinflation.…”

Directional Biomechanical Properties of Porcine Skin Tissue

“…Stresses are calculated based on the force divided by the size of the sample  the recorded thickness of the sample. The displacements are obtained from the relative positions of the rigid biorakes (from the actuators), and it is different from what have been presented in Fung's and others' work, [16][17][18]29,30 where few dots on the samples or a rectangular grid consisting of few points were generally used to calculate the displacements or strains during the biaxial testing. After averaging over measured stress versus strain for tissue samples (n ¼ 6) for each testing angle under equibiaxial testing, the results are shown in Fig.…”

How Locusts Breathe

“…Most obviously, some tracheae (e.g., the transverse tracheae leading from the cardiac longitudinal to the spiracles) do not compress and seem to function as conducting elements for air within the system. It should be noted that compression of tracheae in locusts, as in other insects, is often localized, with some regions within a tracheae compressing strongly, suggesting that specific locations in the tracheae have weak points that reduce resistance to compression (49). Collapsing tracheae may function as valves to regulate flow between segments and regions, in addition to serving as air pumps.…”