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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

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.
Topics: Compliant mechanism (56%)
References
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Journal ArticleDOI
Ole Sigmund1Institutions (1)
Abstract: This paper presents a method for optimal design of compliant mechanism topologies. The method is based on continuum-type topology optimization techniques and finds the optimal compliant mechanism topology within a given design domain and a given position and direction of input and output forces. By constraining the allowed displacement at the input port, it is possible to control the maximum stress level in the compliant mechanism. The ability of the design method to find a mechanism with complex output behavior is demonstrated by several examples. Some of the optimal mechanism topologies have been manufactured, both in macroscale (hand-size) made in Nylon, and in microscale (<.5mm)) made of micromachined glass.

1,162 citations


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

  • ...Pseudo rigid-body models [9] and topology optimization [15–17] are widely used for designing the geometric form and topological configuration of compliant mechanisms....

    [...]


Journal ArticleDOI
Abstract: Compliant mechanisms are mechanical devices that achieve motion via elastic deformation. A new method for topological synthesis of single-piece compliant mechanisms is presented, using a “design for required deflection” approach. A simple beam example is used to illustrate this concept and to provide the motivation for a new multi-criteria approach for compliant mechanism design. This new approach handles motion and loading requirements simultaneously for a given set of input force and output deflection specifications. Both a truss ground structure and a two-dimensional continuum are used in the implementation which is illustrated with design examples.

429 citations


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

  • ...Pseudo rigid-body models [9] and topology optimization [15–17] are widely used for designing the geometric form and topological configuration of compliant mechanisms....

    [...]


Journal ArticleDOI
Abstract: Cemented sands are found in many areas of the world; one of their distinguishing characteristics is their ability to stand in steep natural slopes. Large deposits are located along the California coast, and in a number of areas intense urban development has occurred near the crest of high, steep slopes. Because of the hazards posed by slope failures in the cemented sands, a test program was undertaken to define the nature of the cementation and its effect on behavior of the soils. A total of 137 laboratory compression and tension load tests were performed on undisturbed samples of naturally cemented sands and artificially prepared cemented sands. The materials exhibited friction angles similar to uncemented sands, but had a cementation strength intercept and a tensile strength. The primary cementing agents of the sands tested were silicates and iron oxides. The strength of the cemented sands were found to be a function of density, amount of cementing agent, grain shape and grain arrangement.

413 citations


Journal ArticleDOI
Larry L. Howell1, Ashok Midha1Institutions (1)

403 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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Book
17 May 2011
Abstract: Introduction Use of DEM in Geomechanics Calculation of Contact Forces Particle Motion Particle Types Boundary Conditions Initial Geometry and Specimen Generation Time Integration and Discrete Element Modelling DEM Interpretation: A Continuum Perspective Postprocessing: Graphical Interpretation of DEM Simulations Basic Statistical Analysis of Particulate Systems Guidance on Running DEM Simulations DEM: Future and Ongoing Developments

354 citations