California Institute of Technology

Louisiana State University and Agricultural & Mechanical College

Guruswami Ravichandran

Kaushik Bhattacharya

Md Zubaer Hossain

Chun-Jen Hsueh

Axel Scherer

Morteza Gharib

Harry A Atwater

Demetri Psaltis

Arash Kheradvar

Shiming Zhuang

Blaise Aurélien Bourdin

Theresa Kidd

Rongjing Zhang

Doron Shilo

Kaushik Dayal

Matthew Dicken

Systems and methods in accordance with embodiments of the invention determine the effective toughness of a given material, and also implement materials possessing improved effective toughness values. In one embodiment, a method of determining the effective toughness of a material includes: causing a crack to propagate through the material; where the relative constant velocity and the relative overall direction are prescribed and maintained for the duration of the propagation of the crack through the material; measuring the energy release rate of the crack as it propagates through the material; and defining the effective toughness of the material as the maximum value of the measured energy release rate.

Systems and methods for determining the effective toughness of a material and for implementing materials possessing improved effective toughness characteristics

Methods for measuring the effective fracture toughness in a material are described. A rail and roller system are used to apply a gradual force to a specimen. The time-dependent force creates a steady fracture development that allows a camera to record the progressive fracture in the material. Mathematical methods can then be used to analyze the fracture progression and determine the effective fracture toughness.

Measurement of fracture toughness of heterogeneous materials

An apparatus for simultaneously measuring longitudinal and shear wave speeds in materials under load via echo or transmission is described. The apparatus comprises a housing with an open end, a closed end opposite the open end with a hole in the closed end, and a housing exit port. A spacer resides inside the housing, the spacer having a spacer specimen side and a spacer transducer side. A load transferring body having a transducer hole fits inside the housing and contacts an interior surface of the housing. An ultrasonic transducer fits inside the transducer hole of the load transferring body. A transducer depressing mechanism secures the ultrasonic transducer against the spacer transducer side, whereby users can simultaneously measure longitudinal and shear wave speeds of specimens inserted into the hole in the closed end of the housing and contacting the spacer.

Apparatus for simultaneously measuring longitudinal and shear wave speeds in materials under compression load via an ultrasonic transducer

The present invention relates to the field measuring the mechanical response of micro-electro-mechanical systems. More specifically, the present invention pertains to a method and apparatus that allows the direct control of the load applied to a Micro-Electro-Mechanical System in order to measure the mechanical response. The system comprises a loading sub-system, a displacement measurement sub-system, and an optional observation sub-system.

Method and apparatus for measuring the mechanical response of micro-electro-mechanical systems

Systems and methods for manipulating light with tunable ferroelectric photonic devices. Devices having tunable properties that exhibit photonic bandgap behavior are fabricated from ferroelectric materials. Apparatus is provided to apply tuning signals to the ferroelectric material using one or more of electric fields, mechanical forces, optical fields, and thermal fields. Control circuitry is provided to generate the control signals needed to apply the tuning signals. Input and output ports are provided to allow input signals to be received and to provide output signals. In some cases, a feedback loop is provided to use a portion of the output signal as a diagnostic signal for control of the operation of the device within an acceptable range. It is expected that ferroelectric photonic devices operating according to principles of the invention will be useful for a wide variety of applications, including optical switching, optical modulation, optical computing, and performing logic optically.

Ferroelectric nanophotonic materials and devices

An implantable prosthetic valve that is transformable from a first helical pre-implantation configuration to a second valvular functional configuration, and methods of delivery.

Implantable small percutaneous valve and methods of delivery

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Arcadia, CA, United States of America

Guruswami Ravichandran