Abstract:Orb webs absorb the impact energy of prey and transmit vibratory information to the spider with minimal structural damage. The structural properties of the web and the arrangement of threads within the web affect transmission time during the prey impact. The objective of the present study is to determine damping, stiffness, and transmissibility of healthy and damaged spider webs. Experimental results show that stiffness and transmissibility diminish from the inner to outer spiral threads and gradient variation… Show more
“…The image displays the motion of the orb web in the deformed geometry frame considering the transverse normalized displacement field. The frequency range of the modes predicted with the simulation box agrees with in-situ experimental work on real orb webs 29 , 30 . Figure 2 (Color online) Vibration eigenmodes of the spider web, modeled by pre-stressed trusses with geometrical nonlinearity.…”
Section: Methodssupporting
confidence: 77%
“…The image displays the motion of the orb web in the deformed geometry frame considering the transverse normalized displacement field. The frequency range of the modes predicted with the simulation box agrees with in-situ experimental work on real orb webs 29,30 .…”
Spider webs are finely tuned multifunctional structures, widely studied for their prey capture functionalities such as impact strength and stickiness. However, they are also sophisticated sensing tools that enable the spider to precisely determine the location of impact and capture the prey before it escapes. In this paper, we suggest a new mechanism for this detection process, based on potential modal analysis capabilities of the spider, using its legs as distinct distributed point sensors. To do this, we consider a numerical model of the web structure, including asymmetry in the design, prestress, and geometrical nonlinearity effects. We show how vibration signals deriving from impacts can be decomposed into web eigenmode components, through which the spider can efficiently trace the source location. Based on this numerical analysis, we discuss the role of the web structure, asymmetry, and prestress in the imaging mechanism, confirming the role of the latter in tuning the web response to achieve an efficient prey detection instrument. The results can be relevant for efficient distributed impact sensing applications.
“…The image displays the motion of the orb web in the deformed geometry frame considering the transverse normalized displacement field. The frequency range of the modes predicted with the simulation box agrees with in-situ experimental work on real orb webs 29 , 30 . Figure 2 (Color online) Vibration eigenmodes of the spider web, modeled by pre-stressed trusses with geometrical nonlinearity.…”
Section: Methodssupporting
confidence: 77%
“…The image displays the motion of the orb web in the deformed geometry frame considering the transverse normalized displacement field. The frequency range of the modes predicted with the simulation box agrees with in-situ experimental work on real orb webs 29,30 .…”
Spider webs are finely tuned multifunctional structures, widely studied for their prey capture functionalities such as impact strength and stickiness. However, they are also sophisticated sensing tools that enable the spider to precisely determine the location of impact and capture the prey before it escapes. In this paper, we suggest a new mechanism for this detection process, based on potential modal analysis capabilities of the spider, using its legs as distinct distributed point sensors. To do this, we consider a numerical model of the web structure, including asymmetry in the design, prestress, and geometrical nonlinearity effects. We show how vibration signals deriving from impacts can be decomposed into web eigenmode components, through which the spider can efficiently trace the source location. Based on this numerical analysis, we discuss the role of the web structure, asymmetry, and prestress in the imaging mechanism, confirming the role of the latter in tuning the web response to achieve an efficient prey detection instrument. The results can be relevant for efficient distributed impact sensing applications.
“…Despite their ubiquitous presence, experts from physics, materials science, and biology are still uncovering the elusive mechanics of spiderwebs that enable them to be remarkably robust vibration sensors. [29,30] Spider silk threads have high toughness and stiffness, reaching yield strengths of the order of a gigapascal-about five times higher than steel [31] and about the same as Si 3 N 4 . They are used to create lightweight fibrous web structures which harbor an extraordinary strength-to-weight ratio rarely observed among other structures found in nature or science.…”
temperature conditions where thermomechanical noise can dominate. The degree of mechanical isolation is characterized by a resonator's mechanical quality factor, Q m . Typically, Q m is defined as the ratio of energy stored in a resonator over the energy dissipated over one cycle of oscillation. Inversely, mechanical quality factors can indicate the dissipation of mechanical noise into a resonator from ambient environments. For mechanical sensors, a resonator's isolation from ambient thermal noise can greatly enhance their ability to detect ultrasmall forces, pressures, positions, masses, velocities, and accelerations. For quantum technologies, mechanical quality factor dictates the average number of coherent oscillations a nanomechanical resonator (in the quantum regime) can undergo before one phonon of thermal noise enters the resonator and causes decoherence of its quantum properties. [1] From microchip sensing to quantum networks, cryogenics are conventionally required to counteract thermal noise but enabling these burgeoning technologies to operate in ambient temperatures would have a significant impact on their widespread use.In room-temperature environments, on-chip mechanical resonators with state-of-the-art quality factors have mostly consisted of high-aspect-ratio suspended nanostructures From ultrasensitive detectors of fundamental forces to quantum networks and sensors, mechanical resonators are enabling next-generation technologies to operate in room-temperature environments. Currently, silicon nitride nanoresonators stand as a leading microchip platform in these advances by allowing for mechanical resonators whose motion is remarkably isolated from ambient thermal noise. However, to date, human intuition has remained the driving force behind design processes. Here, inspired by nature and guided by machine learning, a spiderweb nanomechanical resonator is developed that exhibits vibration modes, which are isolated from ambient thermal environments via a novel "torsional soft-clamping" mechanism discovered by the data-driven optimization algorithm. This bioinspired resonator is then fabricated, experimentally confirming a new paradigm in mechanics with quality factors above 1 billion in room-temperature environments. In contrast to other state-of-the-art resonators, this milestone is achieved with a compact design that does not require sub-micrometer lithographic features or complex phononic bandgaps, making it significantly easier and cheaper to manufacture at large scales. These results demonstrate the ability of machine learning to work in tandem with human intuition to augment creative possibilities and uncover new strategies in computing and nanotechnology.
Spider webs are mechanical systems able to deliver an outstanding compromise between distinct requirements such as absorbing impacts and transmitting information about vibration sources. Both the frequency information and amplitude of input signals can be used by the spider to identify stimuli, aided by the mechanical filtering properties of orb webs. In this work, a numerical model based on nonlinear stress–strain constitutive relations for spider silk is introduced to investigate how the spider orb web allows spiders to detect and localize prey impacts. The obtained results indicate how the orb web center relative transverse displacements, produced by local resonance mechanisms, are used for precise localization, while nonlinear stress stiffening effects improve prey sensing. Finally, it is also shown that, although beneficial, a large number of radial threads may not be necessary for prey localization.
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