Session: SYMP 4-7: Multi-stable Smart Systems

Paper Number: 148150

148150 - Compliant Building Blocks of Mechanical Computing 

Mechanical computing offers an alternative to electronic computing for applications that involve extreme environments or that inhibit the use of electrical power sources. Mechanical computers can operate in environments that are hostile to conventional electronics, including those with extreme temperatures, high radiation, or harsh chemical conditions. Furthermore, mechanical computing is powered by a combination of external stimuli and internal structural and material responses, rather than relying on electrical power. This makes mechanical computing advantageous for long-duration, battery-free applications. In this work, we present the building blocks for mechanical circuits using compliant mechanisms: monostable and bistable bits, basic logic gate functions, and reversible signal propagation.

 

In this particular architecture, the mechanical logic building blocks are designed using compliant mechanism elements to control the kinematic and structural responses. Compliant mechanisms rely on bending, rather than contact to actuate, and thus are not limited by friction when scaled across micro to macro scales. First, we present an analog bit that exhibits a continuous response to external force or displacement inputs. We present a sensitivity analysis examining the effects of tuning different geometric parameters and varying the bit’s constituent compliant mechanism design elements. This analog bit serves as an input to our second building block, a bistable memory bit. The bistable states of the memory bit represent a stored value of ‘1’ or ‘0’, analogous to the binary transistor in conventional electronics. Zero degree of freedom stiffeners tune the energy barrier of the bistable bit. A chain of bistable bits with decreasing energy barrier levels enables reversible, nonreciprocal signal propagation to transmit the input value through the mechanical system. Finally, we use compliant mechanism design to create an AND gate, which converts two independent inputs to a single output, which then interfaces with downstream mechanical logic elements or with a conventional electronic system. The building blocks are analyzed using finite element analysis and experimentally demonstrated with 3D printed architectures spanning meter to micron length scales. Future work includes expanding our available set of inputs by integrating smart, stimuli-responsive materials, as well as investigating the use of higher order stable states for more efficient information storage. Ultimately, we are developing a robust, modular library of input, output, memory, and logic elements to enable the use of mechanical computing across a wide range of applications.

 

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-863401

 

Presenting Author: Katherine S. Riley Lawrence Livermore National Laboratory

Presenting Author Biography: Katherine Riley is a mechanical research engineer at Lawrence Livermore National Laboratory. She received her BS in structural engineering from the University of California, San Diego and her MS and PhD in mechanical engineering from Purdue University. Her research interests include multistable structures, programmable materials, and mechanical systems that can sense, remember, and compute.

Authors:

Katherine S. Riley
Hilary A. Johnson
Logan Bekker
Robert M. Panas
John Cortes Gutierrez
Jonathan B. Hopkins
Andrew J. Pascall