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Journal ArticleDOI

Design of a Portable Compliant Device for Estimating the Failure-Load of Mesoscale Cemented Sand Specimens

01 Jun 2015-Journal of Mechanical Design (American Society of Mechanical Engineers)-Vol. 137, Iss: 6, pp 065001
TL;DR: In this paper, a hand-operated compliant mechanism for estimating the failure load of cm-sized stiff objects whose stiffness is of the order of 10 s of kN/m was presented.
Abstract: In this paper, we present the design and development of a portable, hand-operated composite compliant mechanism for estimating the failure-load of cm-sized stiff objects whose stiffness is of the order of 10 s of kN/m. The motivation for the design comes from the need to estimate the failure-load of mesoscale cemented sand specimens in situ, which is not possible with traditional devices used for large specimens or very small specimens. The composite compliant device, developed in this work, consists of two compliant mechanisms: a force-amplifying compliant mechanism (FaCM) to amplify sufficiently the force exerted by hand in order to break the specimen and a displacement-amplifying compliant mechanism (DaCM) to enable measurement of the force using a proximity sensor. The two mechanisms are designed using the selection-maps technique to amplify the force up to 100N by about a factor of 3 and measure the force with a resolution of 15 mN. The composite device, made using a FaCM, a DaCM, and a Hall effect-based proximity sensor, was tested on mesoscale cemented sand specimens that were 10mm in diameter and 20mm in length. The results are compared with those of a large commercial instrument. Through the experiments, it was observed that the failure-load of the cemented sand specimens varied from 0.95N to 24.33 N, depending on the percentage of cementation and curing period. The estimation of the failure-load using the compliant device was found to be within 1.7% of the measurements obtained using the commercial instrument and thus validating the design. The details of the design, prototyping, specimen preparation, testing, and the results comprise the paper.
References
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01 Jan 2006
TL;DR: The theory and math behind the Hall effect can be found in this article, where the authors present a detailed discussion of the theoretical and practical Hall effect transducers and transducer geometry.
Abstract: 1. Hall Effect Physics The theory and math behind the Hall effect. 2. Practical Hall Effect Transducers Key characteristics, integrated Hall transducers, transducer geometry, examples. 3. Transducer Interfacing Modeling Hall transducers, biasing, amplifiers, temp. compensation, offset adjustment. 4. Integrated Sensors, Linear and Digital Devices Linear sensors, switches and latches, speed sensors, application-specific devices. 5. Interfacing to Integrated Hall Sensors Interface issues, line driver circuits, the pull-up resistor, interfacing to standard logic devices, discrete logic, driving loads, LED interface, incandescent lamps, relays, solenoids, and inductive loads, wiring reduction schemes, encoding and serialization, digital to analog encoding, voltage regulation and power management. 6. Proximity Sensing Techniques Head-on sensing, slide-by sensing, magnet null-point sensing, float-level sensing, linear position sensing, rotary position sensing, Vane switches, 7. Current Sensing Resistive current sensing, free-space current sensing, toroidal current sensors, digital current sensor, closed-loop current sensors. 8. Speed and Timing Sensors Competitive technologies, magnetic targets, vane switches, geartooth sensing, single-point sensing, differential fixed threshold, differential variable-threshold, speed and direction sensing. 9. Application-Specific Hall Sensor ICs Micro-power switches, two-wire switches, networkable sensors, power devices, smart motor control. 10. Development Tools for Hall Effect Sensors Electronic bench equipment, magnetic instrumentation, mechanical tools, magnetic simulation software. Appendix A. Brief Introduction to Magnetics Appendix B. Suppliers List Glossary References and Bibliography Index

342 citations

Journal ArticleDOI
TL;DR: In this paper, an optimal structural property for compliant topologies is presented for general multicriteria formulations that comprise the conflicting flexibility and stiffness requirements, and a one-variable search along the direction determined by the above optimal property is ensured that the converged solution is a minimum.
Abstract: An optimal structural property for compliant topologies is presented in this paper for general multicriteria formulations that comprise the conflicting flexibility and stiffness requirements. The property deduced from the first-order necessary conditions for optimality implies that the ratio of the mutual potential energy density to the strain energy density is uniform throughout the continuum, but for portions otherwise bounded by gage constraints. This property is used to develop an optimality criteria method for synthesizing compliant topologies. It is also noted that the multicriteria formulations considered here are nonconvex and can result in nonunique solutions. However, by incorporating a one-variable search along the direction determined by the above optimal property, it is ensured that the converged solution is a minimum. Several synthesis examples are included with linear frame finite elements which are easy for implementation and are capable of appropriately accounting for the bending behaviour in the continuum. Examples with previously reported density based design parameterization using bilinear plane-stress elements are also included to illustrate the synthesis procedure.

248 citations


"Design of a Portable Compliant Devi..." refers background or methods in this paper

  • ...DaCMs [12,27] developed in the context of sensors are relevant to this paper....

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  • ...The chosen DaCM in the database was reported by Saxena and Ananthasuresh [27]....

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Journal ArticleDOI
TL;DR: In this article, a numerical investigation of shear behavior and strain localization in cemented sands using the distinct element method (DEM) employing two different failure criteria for grain bonding is presented.

165 citations


Additional excerpts

  • ...Various phenomenological models have been developed [2–4] in order to explain the mechanical behavior of cohesive-frictional granular materials....

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Journal ArticleDOI
TL;DR: In this paper, the authors propose a compliant mechanism topology based on a linkage consisting of rigid members connected together with revolute joints to maximize the flexibility for obtaining desired output motion while maximizing the overall stiffness for satisfactorily bearing the applied loads.
Abstract: The optimization problem formulations currently used to synthesize compliant mechanism topologies aim to maximize the flexibility for obtaining the desired output motion while maximizing the overall stiffness for satisfactorily bearing the applied loads. The best solution to this problem, as posed, is a linkage consisting of rigid members connected together with revolute joints. The current elastic mechanics-based formulations do generate compliant topologies that closely imitate a rigid-body linkage by means of lumped compliance as in flexural pivots. Systematically generating such topology solutions could serve as a creative aid in the conceptual design of mechanisms, especially when the force-deflection specifications are nonintuitive to human designers. However, flexural pivot-based compliant designs are not useful in most applications when large displacements and/or high strength are desired. Ideally, compliant designs should distribute flexibility uniformly throughout the structure rather t...

129 citations


"Design of a Portable Compliant Devi..." refers methods in this paper

  • ...Using these methods, many types of compliant mechanisms, such as flexure-based [21,22], distributed compliant [23], partially compliant [24], contact-aided [25], and laminaemergent [26], are reported in the literature....

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Journal ArticleDOI
TL;DR: In this article, the authors present a generalized methodology for designing compliant mechanisms for topology generation and size and shape optimization, and demonstrate integration with electrostatic, piezoelectric, and SMA actuators for MEMS and smart-structures applications.
Abstract: Matching a drive system to the force-displacement characteristics of the load is the cardinal principle in electromechanical systems design. Unconventional actuation schemes; such as piezoelectric, electrostatic, and shape-memory alloys (SMAs), seem to exhibit certain limitations in terms of power density, stroke length, bandwidth, etc., when one attempts to employ them directly to an application. Integrating them with mechanical transmission elements so that the integrated actuator-transmission system matches the load characteristics of the application can enhance the utility of such unconventional actuators. Conventional mechanical devices are sometimes difficult to integrate with unconventional actuating schemes. For instance, the two-dimensional nature of microelectromechanical systems (MEMS) and no-assembly constraints arising from their batch fabrication make it difficult to fabricate, assemble, and integrate a conventional micromechanism with an electrostatic actuator. However, a monolithic "solid-state" mechanical transmission device enables easy integration. The paper presents a systematic method of designing such unconventional mechanisms. The paper presents a generalized methodology for designing compliant mechanisms. Our systematic synthesis formulations provide a mathematical basis for designing compliant mechanisms for: (1) topology generation and (2) size and shape optimization. Design examples illustrate integration with electrostatic, piezoelectric, and SMA actuators for MEMS and smart-structures applications.

128 citations


Additional excerpts

  • ...They can be used as transmissions [10], actuators [11], and sensors [12,13]....

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