Flexural rigidity

About: Flexural rigidity is a research topic. Over the lifetime, 3829 publications have been published within this topic receiving 56780 citations.

Anisotropic Patterning to Reduce Instability of Concentric-Tube Robots

Abstract: As a steerable needle or robotic manipulator, the concentric-tube robot shows good potential for use in minimally invasive medical procedures. However, the torsional deformation of the precurved tubes comes at the price of instability, which not only limits the workspace and tool path but also potentially creates danger of tissue rupture when external load is applied. In this paper, we propose anisotropic patterning of tubes to solve the instability problem. Hole-patterning can tune the mechanical properties of the tubes so that the ratio of the torsional rigidity to the bending rigidity becomes higher. This study investigates the effect of pattern design parameters by building a lumped analytical model and examining it with finite-element analysis. The pattern is engraved via laser machining and we experimentally verify that material anisotropy reduces instability.

Mechanical Properties of the Rice Panicle

Abstract: Curvature, bending moment, and second moment of stem cross-sectional area were evaluated from photographic data and used to compute flexural rigidity and Young9s modulus in the panicle rachis of rice, Oryza sativa L. `M-101.9 Flexural rigidity C , and its components E , Young9s modulus, and I , the moment of inertia of the area about the neutral axis, were evaluated 1.5 cm (tip), 9.5 cm (mid), and 16.5 cm (base) from the tip of the panicle rachis. In dynes per square centimeter, C increases from 1.1 × 10 3 near the tip to 1.09 × 10 4 in the middle to 5.35 × 10 4 in the basal region of the rachis. Of the components of C , the I changes have the larger effect, increasing from 2.12 × 10 −7 centimeters 4 near the tip to 8.21 × 10 −7 centimeters 4 in mid regions to 6.0 × 10 −6 centimeters 4 in the basal regions. Young9s modulus increases from 4.8 × 10 9 dynes per square centimeter near the tip to 1.4 × 10 10 dynes per square centimeter in mid regions then falls to 7.4 × 10 9 dynes per square centimeter near the base of the main stem. Values of Young9s modulus from Instron experiments were in satisfactory agreement with values calculated from the beam bending equation. Flexural rigidity in the curved region of the panicle proved independent of panicle load, indicating that the dissected panicle rachis behaves in some respects as a tapered loaded beam.

The Effect of Fibre Cross-sectional Shape on Fabric Mechanical Properties and Handle

Abstract: In order to clarify the effects of different fibre cross-sectional shapes on fabric mechanical properties and handle, polyester ‘Shingosen’ fabrics of different fibre cross-sections were investigated using the KES-FB system. The results were discussed by comparing them with typical women's fine dress fabrics and the following conclusions were obtained. Polyester fabric becomes soft and deformable with an increase in the space ratio in the fibre cross-section, however, it does become inelastic and unrecoverable. FUKURAMI (fullness and softness) and SHINAYAKASA (flexibility with a soft feel) of polyester fabrics is greater with higher space ratios, but, KOSHI (stiffness) and HARI (and-drape stiffness), however, is lowered. Fabric bending rigidity is in proportion to fibre bending rigidity if all other conditions such as yarn density, count and finishing conditions remain the same. However, in general, the fabric mechanical properties and handle are controlled by the fibre assembly structure rather than fibr...

Post-fire flexural performance of epoxy-nanocomposite matrix glass fibre composites containing conventional flame retardants

Abstract: This paper investigates the effect of varied nanoparticles (silicate nanoclays and double-walled carbon nanotubes) and micro-sized flame retardants (FRs) on the post heat/fire flexural performance of glass fibre-reinforced (GFR) epoxy composites. The fire reaction properties of GFR epoxy composites containing different combinations of nano- and micro-sized FRs were studied at varied incident heat fluxes (35–75 kW/m2). The flexural stiffness and modulus values of radiant heat-damaged GFR composites decreased rapidly with increasing incident heat flux. On another hand, the post-fire flexural properties of these specimens exposed for 30–90 s post-ignition at 50 kW/m2 retained only 20% of their room temperature flexural properties. Despite significant improvements in the fire reaction properties, their post-fire flexural performance was least affected. This suggests that, while these flame retardants are effective in promoting char formation, the formed char networks are not consolidated enough to effectively constrain the fibre reinforcements.