scholarly journals Leveraging elastic instabilities for amplified performance: Spine-inspired high-speed and high-force soft robots

2020 ◽  
Vol 6 (19) ◽  
pp. eaaz6912 ◽  
Author(s):  
Yichao Tang ◽  
Yinding Chi ◽  
Jiefeng Sun ◽  
Tzu-Hao Huang ◽  
Omid H. Maghsoudi ◽  
...  
Keyword(s):  
Body Length ◽  
High Speed ◽  
High Performance ◽  
Design Principle ◽  
Load Capacity ◽  
Soft Materials ◽  
Maximum Load ◽  
Mechanical Instability ◽  
Soft Robots ◽  
Generic Design

Soft machines typically exhibit slow locomotion speed and low manipulation strength because of intrinsic limitations of soft materials. Here, we present a generic design principle that harnesses mechanical instability for a variety of spine-inspired fast and strong soft machines. Unlike most current soft robots that are designed as inherently and unimodally stable, our design leverages tunable snap-through bistability to fully explore the ability of soft robots to rapidly store and release energy within tens of milliseconds. We demonstrate this generic design principle with three high-performance soft machines: High-speed cheetah-like galloping crawlers with locomotion speeds of 2.68 body length/s, high-speed underwater swimmers (0.78 body length/s), and tunable low-to-high-force soft grippers with over 1 to 103 stiffness modulation (maximum load capacity is 11.4 kg). Our study establishes a new generic design paradigm of next-generation high-performance soft robots that are applicable for multifunctionality, different actuation methods, and materials at multiscales.

Foil Bearings Makes Oil-Free Turbocharger Possible

2005 ◽  
Author(s):  
Crystal A. Heshmat ◽  
Hooshang Heshmat ◽  
Mark J. Valco ◽  
Kevin C. Radil ◽  
Christopher Della Corte
Keyword(s):  
High Speed ◽  
Solid Lubricant ◽  
Load Capacity ◽  
Maximum Load ◽  
Solid Lubricant Coating ◽  
Foil Bearings ◽  
Wide Range ◽  
Rotor Bearing ◽  
Component Development ◽  
Bearing System

This paper describes an oil-free, 150 Hp turbocharger that was successfully operated with compliant foil bearings in a range of pitch and roll angles, including vertical operation, thereby demonstrating its viability for aircraft applications. On a gas test stand the turbocharger was operated to 120,000 rpm, under extreme conditions. In addition, the compliant foil bearing-supported turbocharger successfully tolerated shock and vibration of 40 g. Advanced technologies have been applied to the second generation of this turbocharger, shown in Figure 1, including self acting, compliant foil hydrodynamic air bearings with advanced coatings capable, of operation above 815 °C (1500°F). Journal foil bearings with maximum load capacity up to 670 kPa (97 psi) were used in conjunction with thrust foil bearings capable of maximum loads to 570 kPa (83 psi). Bearing component development tests demonstrated 30,000 start stop cycles at 815 °C (1500°F) with a newly developed, solid lubricant coating, KOROLON™. KOROLON™ exhibits a coefficient of friction of less than 0.1 at a wide range of temperatures. Current-designed foil bearings with KOROLON™ have immensely decreased turbolag, allowing acceleration from rest to over 100,000 rpm in less than 2 seconds. Advanced bearing stiffness maintained rotor total axial end-to-end motion within 100 microns (0.004 inch). Total radial static and dynamic motion was controlled within 25 microns (0.001 inch). Development of this high speed turbomachine included bearing and solid lubricant component development tests, rotor-bearing dynamic simulator qualification and gas stand tests of the assembled turbocharger. Gas stand and simulator test results revealed stable bearing temperatures, low rotor vibrations, good shock tolerance and the ability of the rotor bearing system to sustain overspeed conditions beyond 120,000 rpm. This combination of component and integrated rotor-bearing system technology addresses many of the issues associated with application of compliant foil bearings to industrial compressors, blowers, and gas turbine engines, overcoming many of the inherently show-stopping and debilitating features of rolling element bearings, i.e., speed and temperature limitations.

scholarly journals Design and Implementation of a Fault-Tolerant Magnetic Bearing System for MSCMG

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Enqiong Tang ◽  
Bangcheng Han
Keyword(s):  
High Speed ◽  
Fault Tolerant ◽  
Control Strategies ◽  
Load Capacity ◽  
Maximum Load ◽  
Magnetic Bearing ◽  
Before And After ◽  
Key Factor ◽  
Gyroscopic Coupling ◽  
Bearing System

The magnetically suspended control moment gyros (MSCMGs) are complex system with multivariable, nonlinear, and strongly gyroscopic coupling. Therefore, its reliability is a key factor to determine whether it can be widely used in spacecraft. Fault-tolerant magnetic bearing systems have been proposed so that the system can operate normally in spite of some faults in the system. However, the conventional magnetic bearing and fault-tolerant control strategies are not suitable for the MSCMGs because of the moving-gimbal effects and requirement of the maximum load capacity after failure. A novel fault-tolerant magnetic bearing system which has low power loss and good robust performances to reject the moving-gimbal effects is presented in this paper. Moreover, its maximum load capacity is unchanged before and after failure. In addition, the compensation filters are designed to improve the bandwidth of the amplifiers so that the nutation stability of the high-speed rotor cannot be affected by the increasing of the coil currents. The experimental results show the effectiveness and superiority of the proposed fault-tolerant system.

High-Performance LC Resonant Amplifier Design and Implementation

2014 ◽  
Vol 543-547 ◽  
pp. 677-680
Author(s):  
Yue Tao ◽  
Ze Wu
Keyword(s):  
High Speed ◽  
High Performance ◽  
Electromagnetic Compatibility ◽  
Load Capacity ◽  
Impedance Matching ◽  
Basic Function ◽  
Control Area ◽  
Output Stage ◽  
Amplifier Design ◽  
System Frequency

The work mainly by the front level attenuator, the LC tuned amplifier, the push-pull output stage is composed. The first level weakens 40dB fixedly through pi the attenuator realization. Front the double grid field effect manages 3SK223 to make the level to increase the controllable LC tuned amplifier, the LC resonance by double harmonious and the list harmonious cascade way, enhanced the system selectivity. The complete machine gain is bigger than the 80dB, AGC control area to achieve above 60dB.The output stage uses the low pressure high electric current high speed axle to the axle structure integration operational amplifier OPA2354 push-pull transformer coupling output, sharpened the belt load capacity greatly. In order to reduce the amplifier as far as possible the noise and ceases the high frequency auto excitation, this design has adopted the power source filter, the shield, electromagnetic compatibility, the interstate coupling, the impedance matching and so on many kinds of measures. After the test, this plan has completed completely the basic function and the expansion function. Sweeps the frequency source turning on input end after CPLD self-made DDS, May very convenient see the system frequency response on the oscilloscope.

A Virtual Tool for Wear Simulation of Standard and Non-Standard Spur Gears

2012 ◽  
Author(s):  
F. Karpat ◽  
S. Ekwaro-Osire ◽  
E. Karpat
Keyword(s):  
High Speed ◽  
High Performance ◽  
Failure Modes ◽  
Power Transmission ◽  
Wear Behavior ◽  
Gear Tooth ◽  
Load Capacity ◽  
High Load ◽  
Wear Depth ◽  
Spur Gears

There is an industrial demand for the increased performance of mechanical power transmission devices. This need in high performance is driven by high load capacity, high endurance, low cost, long life, and high speed. New designs and modifications in gears have been investigated to obtain high load carrying capacity and increased life with less volume and weight. Tooth wear is one of the major failure modes in gears. Although there are different classifications of wear mechanisms, wear on gears can be simply classified as mild wear, pitting, and severe wear, depending on the wear rate. These types of wear may lead to power transmission losses, decreased efficiency, increased vibration and noise, and gear tooth failure. This paper deals with the simulation of wear for standard and non-standard gears using an analytical approach. A numerical model for wear prediction of gear pair is developed. A wear model based on Archard’s equation is employed to predict wear depth. A MATLAB-based virtual tool is developed to analyze wear behavior of standard and non-standard spur gears with various gear parameters. In this paper, this virtual tool is introduced by using many numerical examples.

scholarly journals Behavior of Non-Shear-Strengthened UHPC Beams under Flexural Loading: Influence of Reinforcement Depth

2021 ◽  
Vol 11 (23) ◽  
pp. 11168
Author(s):  
Mohammad Iqbal Khan ◽  
Galal Fares ◽  
Yassir M. Abbas
Keyword(s):  
Prediction Model ◽  
High Performance ◽  
High Performance Concrete ◽  
Load Capacity ◽  
Maximum Load ◽  
Flexural Behavior ◽  
Moment Capacity ◽  
Flexural Loading ◽  
Beam Design ◽  
Fine Aggregates

This study was carried out in order to study the flexural behavior of fiber-reinforced ultra-high-performance concrete (UHPC) containing hybrid microsteel straight fibers and natural fine aggregates under four-point flexural loading. The experimental results revealed that the fiber pullout mechanism had a progressive pullout (collapse) mode. A highly flexural crack developed when the fiber pulling mechanism was explicitly triggered, leading to the failure of most beams. The maximum load in beams reinforced by 1.2, 1.6, and 2.0% exceeded that in beams without longitudinal reinforcement by 56, 73, and 94%, respectively. Further, bar reinforcements at 125, 115, 95, 85, and 75 mm depths led to increases of 56, 55, 73, 96, and 94% in beam load capacity, respectively. In addition, bar reinforcement at 115, 95, 85, and 75 mm depths reduced the beams’ ductility by 40, 23, 35, and 39% compared to those with 125 mm depth. All studied UHPC beams had an uncracked phase that extended to a curvature of about 7.5 × 10−6 rad, which occurred at about 10 kNm. The use of the design of experiments was exploited in this investigation to develop a prediction model for the ultimate moment capacity of UHPC beams. This prediction model took into account the sectional and material properties of UHPC beams. To carry out this analysis, a database of 25 beams, developed by other investigators, as well as the present authors, was utilized. With a mean prediction-to-test ratio of 0.92, this prediction model had a reasonable performance capacity. In turn, this model was used to generate isoresponsive surface contours that could be used for UHPC beam design.

Challenges in Validating a Thermo-Hydrodynamic Gas Foil Bearing Model

2020 ◽  
Author(s):  
Hanns Michel ◽  
Robert Liebich
Keyword(s):  
Thermal Model ◽  
High Speed ◽  
Load Capacity ◽  
Maximum Load ◽  
Fine Tuning ◽  
Flow Paths ◽  
Operational Conditions ◽  
Foil Bearings ◽  
Wide Range ◽  
The Impact

Abstract Gas foil bearings (GFBs) are suitable for high speed and temperature applications where conventional lubricated bearing solution are not feasible. This requires the pre-diction of bearing temperatures and thus a thermal model considering the heat genera-tion and heat flow paths in the bearing. The effects of two different bump foil stiffness (Iordanoff and Le Lez [1,2]) and heat transfer models (a simplified and a detailed one) are presented in respect to measured temperatures from literature [3,4]. The compari-son is drawn over a wide range of operational conditions as well as measuring posi-tions, which in such detail has not been shown before. While good agreement is found for some of the conditions and positions, only reasonable agreement is found for others. The deviations and difficulties in validating a thermal model against experiments are highlighted in a discussion about various temperature influencing parameters, especial-ly concerning the change of clearance during operation. In conclusion it is found, that the models are able to predict temperatures reasonably well, but require delicate fine-tuning to achieve these results. Finally, the impact of the temperature on the maximum load capacity at a range of speeds is shown in a comparison between an isothermal calculation and one with temperature consideration.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

The bright future of digital imaging in scanning electron microscopy

1993 ◽  
Vol 51 ◽  
pp. 768-769
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Digital Imaging ◽  
High Speed ◽  
High Performance ◽  
Mass Storage ◽  
Analog To Digital ◽  
Central Processing ◽  
Digital Imaging Technology ◽  
Scanning Electron

One of the major advancements applied to scanning electron microscopy (SEM) during the past 10 years has been the development and application of digital imaging technology. Advancements in technology, notably the availability of less expensive, high-density memory chips and the development of high speed analog-to-digital converters, mass storage and high performance central processing units have fostered this revolution. Today, most modern SEM instruments have digital electronics as a standard feature. These instruments, generally have 8 bit or 256 gray levels with, at least, 512 × 512 pixel density operating at TV rate. In addition, current slow-scan commercial frame-grabber cards, directly applicable to the SEM, can have upwards of 12-14 bit lateral resolution permitting image acquisition at 4096 × 4096 resolution or greater. The two major categories of SEM systems to which digital technology have been applied are:In the analog SEM system the scan generator is normally operated in an analog manner and the image is displayed in an analog or "slow scan" mode.

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