scholarly journals Shock Pulse Shaping in a Small-Form Factor Velocity Amplifier

2010 ◽  
Vol 17 (6) ◽  
pp. 787-802 ◽  
Author(s):  
Gerard Kelly ◽  
Jeff Punch ◽  
Suresh Goyal ◽  
Michael Sheehy
Keyword(s):  
Pulse Shaping ◽  
Vertical Axis ◽  
Mechanical Shock ◽  
Practical Applications ◽  
Shock Testing ◽  
Acceleration Signal ◽  
High Acceleration ◽  
Component Assembly ◽  
Small Form Factor ◽  
Shock Pulses

This theme of this paper is the design and characterisation of a velocity amplifier (VAMP) machine for high-acceleration shock testing of micro-scale devices. The VAMP applies multiple sequential impacts to amplify velocity through a system of three progressively smaller masses constrained to move in the vertical axis. Repeatable, controlled, mechanical shock pulses are created through the metal-on-metal impact between pulse shaping test rods, which form part of the penultimate and ultimate masses. The objectives are to investigate the controllable parameters that affect the shock pulses induced on collision, namely; striker and incident test rod material; test rod length; pulse shaping mechanisms; and impact velocity. The optimum VAMP configuration was established as a 60 mm long titanium striker test rod and a 120 mm long titanium incident rod. This configuration exhibited an acceleration magnitude and a primary pulse duration range of 5,800–23,400 g and 28.0–44.0μs respectively. It was illustrated that the acceleration spectral content can be manipulated through control of the test rod material and length. This is critical in the context of practical applications, where it is postulated that the acceleration signal can be controlled to effectively excite specific components in a multi-component assembly affixed to the VAMP incident test rod.

scholarly journals Pulse Shaping in 1D Elastic Waveguides for Shock Testing

2020 ◽  
Author(s):  
William R. Johnson ◽  
Michael J. Leamy ◽  
Washington DeLima ◽  
Massimo Ruzzene
Keyword(s):  
Time Domain ◽  
Pulse Shaping ◽  
Hopkinson Bar ◽  
Phononic Crystals ◽  
Mechanical Shock ◽  
Wave Shape ◽  
Shock Testing ◽  
The Time Domain ◽  
Elastic Waveguides

Abstract Mechanical shock events experienced by electronics systems can be reproduced in the laboratory using Hopkinson bar tests. In these tests a projectile strikes a bar, creating a pulse which travels through the bar into the system. The quality of these tests depends on the closeness of the shape of the incident pulse to the shape specified for the test. This paper introduces a new way to control the shape of the incoming pulse, through the use of elastic metamaterial concepts. Two dispersion-modifying material concepts, phononic crystals, and local resonators, are examined for their wave shaping capabilities in 1D elastic waveguides. They are then evaluated using a transfer matrix method to determine the output wave shape in the time domain. The concepts are then optimized for various pulse shapes, showing that they are most effective when they are tuned to introduce dispersion near the fundamental frequency of the incident wave.

Designing Electronic Products to Withstand the Distribution Environment

1989 ◽  
Vol 111 (4) ◽  
pp. 294-298
Author(s):  
R. Peache ◽  
D. Privitera ◽  
J. Gasper ◽  
D. Heasty
Keyword(s):  
Mechanical Shock ◽  
Shock Testing ◽  
Design Cycle ◽  
Accepted Part ◽  
Shock Resistance ◽  
Product Modification ◽  
The Cost ◽  
And Storage ◽  
Sufficient Strength

During the past few years product mechanical shock fragility analysis has become an accepted part of the product design cycle at Wang Laboratories, Inc. This analysis is used to insure that the product has sufficient strength to work in the user environment without problem, and to survive the shipping environment from Wang to the customer without requiring excessively expensive shipping packaging. In some cases it is possible to make relatively inexpensive changes in the product which increase the mechanical shock resistance of that product. The cost of these changes is weighed against the cost of the amount of cushioning and related recurring costs needed in the shipping package to provide protection for the lower shock level the unmodified product is capable of withstanding. If the cost of product modification is lower than the cost of the increased package materials, freight and storage (increased cube), the modification is made to the product. A brief background of shock testing products is given, with particular attention to the use of ASTM D 3332. This process is presented as a specific case study on a recently developed CRT monitor.

scholarly journals The Dynamics of Multiple Pair-Wise Collisions in a Chain for Designing Optimal Shock Amplifiers

2009 ◽  
Vol 16 (1) ◽  
pp. 99-116 ◽  
Author(s):  
Bryan Rodgers ◽  
Suresh Goyal ◽  
Gerard Kelly ◽  
Michael Sheehy
Keyword(s):  
Power Law ◽  
Low Cost ◽  
Testing Machine ◽  
Design Guidelines ◽  
Mems Devices ◽  
Shock Testing ◽  
Final Mass ◽  
High Acceleration ◽  
Mass Ratios ◽  
A Chain

The major focus of this work is to examine the dynamics of velocity amplification through pair-wise collisions between multiple masses in a chain, in order to develop useful machines. For instance low-cost machines based on this principle could be used for detailed, very-high acceleration shock-testing of MEMS devices. A theoretical basis for determining the number and mass of intermediate stages in such a velocity amplifier, based on simple rigid body mechanics, is proposed. The influence of mass ratios and the coefficient of restitution on the optimisation of the system is identified and investigated. In particular, two cases are examined: in the first, the velocity of the final mass in the chain (that would have the object under test mounted on it) is maximised by defining the ratio of adjacent masses according to a power law relationship; in the second, the energy transfer efficiency of the system is maximised by choosing the mass ratios such that all masses except the final mass come to rest following impact. Comparisons are drawn between both cases and the results are used in proposing design guidelines for optimal shock amplifiers. It is shown that for most practical systems, a shock amplifier with mass ratios based on a power law relationship is optimal and can easily yield velocity amplifications of a factor 5–8 times. A prototype shock testing machine that was made using above principles is briefly introduced.

scholarly journals Quasi-static and mechanical shock testing of reinforced shotcrete surface support

2017 ◽  
Author(s):  
Michael Raffaldi ◽  
Lewis Martin ◽  
Donovan Benton ◽  
Carl Sunderman ◽  
Michael Stepan ◽  
...  
Keyword(s):  
Mechanical Shock ◽  
Shock Testing

How Mitigation Techniques Affect Reliability Results for BGAs

2016 ◽  
Vol 2016 (DPC) ◽  
pp. 001992-002017
Author(s):  
Greg Caswell ◽  
Melissa Keener
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Operating Conditions ◽  
The Other ◽  
Lead Free ◽  
Mechanical Shock ◽  
Sinusoidal Vibration ◽  
Shock Testing ◽  
Mitigation Techniques ◽  
Lead Free Solders ◽  
Mitigation Technique

Since 2006 RoHS requirements have required lead free solders to take the place of tin-lead solders in electronics. The problem is that in some environments the lead free solders are less reliable than the older tin-lead solders. One of the ways to solve this problem is to corner stake, edge bond or underfill the components. When considering what mitigation technique and material to use, the operating conditions must be characterized. The temperature range is important when selecting a material to use since the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are important properties. If improperly chosen, the mitigation material can cause more failures than an unmitigated component. This study focused on 208 I/O BGAs on a 4 layer FR4 board. There were three solders tested; two lead free (SAC305 and SN100C) and one leaded (SnPb). Three mitigation techniques were tested: corner staking, edge bonding, and underfilling. Each of these techniques had two mitigation materials tested. One material was reworkable and the other was not. The boards were subjected to mechanical shock testing and sinusoidal vibration testing until failure. The results of the testing show that no one mitigation technique is best for all of the conditions tested. The same is true for the mitigation material. The best choice of mitigation technique and material is application dependent.

Mechanical Shock Testing of Incremental and Absolute Position Encoders

2021 ◽  
Author(s):  
Federico Allione ◽  
B. Roodra P. Singh ◽  
Antonios E. Gkikakis ◽  
Roy Featherstone
Keyword(s):  
Mechanical Shock ◽  
Absolute Position ◽  
Shock Testing

Certification of 200,000 g Shock Calibration Technique for Sensors

2002 ◽  
Vol 45 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Vesta Bateman ◽  
Philip Thacker
Keyword(s):  
Large Amplitude ◽  
Hopkinson Bar ◽  
Mechanical Shock ◽  
Calibration Technique ◽  
Split Hopkinson Bar ◽  
Split Hopkinson ◽  
Primary Standards ◽  
Shock Pulses

A split Hopkinson bar technique has been developed to evaluate the performance of accelerometers that measure large amplitude, up to 200,000 g, mechanical shock pulses. An evaluation of this technique has been conducted in the Mechanical Shock Laboratory at Sandia National Laboratories (SNL) for use as an accelerometer calibration technique. Results of this evaluation are presented and include a comparison with a NIST calibrated reference accelerometer. The certification of split Hopkinson flyaway technique by the SNL Primary Standards Laboratory is presented in this paper.

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