Chapter 5 Developing Conservative Mechanical Shock Specifications Matthew Baker, Kelsey Neal, Katrina Sweetland, Garrison Stevens, Dustin Harvey, and Stuart Taylor Abstract Mechanical shock testing and analysis are integral parts of developing new high-value items and ensuring their capability to withstand the environments to which they will be exposed. Most conventional methods for specifying mechanical shock environments provide no mathematically defensible correlation between their parameters and the damage-causing potential of the environment, thus warranting the study of new methods to specify shock environments. In this paper, a variety of parameters that correlate to the damage-causing potential of a shock environment are identified. The parameters investigated are restricted to those that can be constrained during a real-time laboratory test. An analytical study using a sensitivity analysis determined the effect of each parameter on the damage-causing potential of a shock environment. These parameters are used to create shock specifications and investigate the simulated response of a structure. The parameters generated in this study improve mechanical shock testing by providing a strong correlation between the shock environment and the damage-causing potential of a mechanical shock. Keywords Mechanical shock • Shock test specification • Shaker shock • Shock severity • Sensitivity analysis 5.1 Introduction A mechanical shock is a sudden acceleration excitation on a structure usually resulting in a significant amount of displacement [1]. Mechanical shocks can be the result of multiple forms of physical excitations, such as jolts, impacts, transportation, and separation. Anticipating mechanical shocks associated with service environments is important because these shocks can damage entire systems or critical components of those systems. The consequences of such damage makes mechanical shock testing critical in the design and development of high-value systems. Without proper mechanical shock testing, there is potential for system failures resulting in devastating consequences. Mechanical shock testing is widely used for product design and development to ensure the reliability of these products in their service environments [2]. Currently, shock testing uses a variety of methods designed to elicit failure modes of the product. These methods include strategies such as testing in the product’s actual service environment, drop testing, and recreating the shock’s damage-causing potential in laboratory testing. Shock testing in a laboratory setting offers some advantages over other forms of testing, including the repeatability of the test [2], which allows for faster design iteration cycles and ultimately faster product development. Laboratory testing also provides a more controlled setting in which mechanical shocks can be applied to the test article. Furthermore, applying mechanical shocks to the test article in a controlled environment, as is the case with laboratory testing, can be safer than alternative testing methods. Recreating the severity of a shock in a laboratory setting requires identification of test specifications, which are derived from the parameters of a mechanical shock. Several methods have been established for defining the test parameters, but the most common method relies on the shock response spectrum (SRS) [3]. The SRS is constructed using the peak acceleration responses from a collection of fictitious single-degree-of-freedom mass-springdamper systems that have a range of natural frequencies and are excited using base excitation. M. Baker • G. Stevens Clemson University, Calhoun Drive, Clemson, SC 29634, USA K. Neal Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, USA K. Sweetland • D. Harvey • S. Taylor (*) Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA e-mail: sgtaylor@lanl.gov #The Society for Experimental Mechanics, Inc. 2016 A. Brandt, R. Singhal (eds.), Shock & Vibration, Aircraft/Aerospace, Energy Harvesting, Acoustics & Optics, Volume 9, Conference Proceedings of the Society for Experimental Mechanics Series, DOI 10.1007/978-3-319-30087-0_5 43
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