How to Build Industrial Computers that Resist Vibration and Shock

WHITE PAPERVibration and ShockIndustrial computersneed to be designed towithstand vibration andshock, which are a factof life in many industrialapplications.Systems should avoidresonance, which allowseven small forces tocreate extreme vibrationand shock.Industrial computer manufacturers need to deliver a product thatis rugged, hardened, and reliable to a degree beyond the consumerstandard. These requirements exist because industrial computersare often deployed in severe conditions and harsh environments,sometimes even on moving vehicles. One key industrialrequirement is vibration and shock resistance, which allowsindustrial computers to operate in truly extreme conditions.There are some industrial applications, such as rolling stock, wherevibration and shock are the most significant factor affecting thestability and reliability of system operations. Computers in rollingstock applications are deployed on moving objects that rattle andshake, so anti-vibration and anti-shock technology is a centralrequirement. Certain rolling stock applications, such as NetworkVideo Recording (NVR) systems, specifically need high storagecapacity to record and store surveillance video images. Hard diskswould be the most reasonable and cost-effective way to store all ofthis data, but deploying hard disks in a high-vibration high-shockenvironment, such as on a bus, train, or truck, is a significantchallenge.This white paper first explains some background about the physicsbehind vibration and shock, and then explores the specificmechanisms and technology used to build an industrial computerwith high resilience against vibration and shock.About VibrationPhysically, there are two kinds of vibrations: free vibration andforced vibration. Free vibration occurs when a mechanical systemis acted on by an initial input and then allowed to vibrate freely.Forced vibration occurs when an oscillating force or motion isapplied to a mechanical system.About ResonanceIn physics, “resonance” describes how a system can oscillate atlarge amplitudes at specific, "resonant" frequencies. An importantpoint that all engineers must keep in mind is that a low amplitudeforce acting at the system's resonant frequency can createextremely large displacements.Resonance occurs in systems that can convert back and forthbetween stored (or potential) energy and kinetic energy. Theclassic example of a resonant system is a pendulum, whichalternates between states of high-kinetic and low-potential energy(when the pendulum moves through the vertical position at thebottom of its swing) and low-kinetic and high-potential energy(when the pendulum slows down and then reverses direction). Thependulum will swing at its resonant frequency if the only externalforce is gravity. Although a simple pendulum has only oneReleased on October 1, 2010Copyright © 2010 Moxa Inc., all rights reserved.Moxa manufactures one of the world’s leading brands of device networking solutions. Products include industrialembedded computers, industrial Ethernet switches, serial device servers, multiport serial boards, embedded deviceservers, and remote I/O solutions. Our products are key components of many networking applications, includingindustrial automation, manufacturing, POS, and medical treatment facilities.How to contact MoxaTel: 1-714-528-6777Fax: 1-714-528-6778Web: www.moxa.comEmail: info@moxa.comThis document was produced by the Moxa Technical WritingCenter (TWC). Please send your comments or suggestions aboutthis or other Moxa documents to twc@moxa.com.Copyright © 2010 Moxa Inc.1