{"id":557439,"date":"2024-11-05T18:18:02","date_gmt":"2024-11-05T18:18:02","guid":{"rendered":"https:\/\/pdfstandards.shop\/product\/uncategorized\/esdu-090052009\/"},"modified":"2024-11-05T18:18:02","modified_gmt":"2024-11-05T18:18:02","slug":"esdu-090052009","status":"publish","type":"product","link":"https:\/\/pdfstandards.shop\/product\/publishers\/esdu\/esdu-090052009\/","title":{"rendered":"ESDU 09005:2009"},"content":{"rendered":"

INTRODUCTION<\/strong><\/p>\n

This Item is intended to provide introductory and background
\ninformation to a series of Items that consider some aspects of
\ndamping in more detail. For example, ESDU 07011 (Reference 43) is
\nconcerned with radiation damping and ESDU 09006 (Reference 44)
\npresents a description of material damping. Future Items will deal
\nwith the damping of composites and the provision of a compendium of
\ndamping for built-up structures. In this Item concepts related to
\ndifferent measures applied to damping in materials, as well as to
\ndamping in mechanical systems, are introduced. Every structure in
\nvibration can be approximated by a dynamically equivalent
\nmechanical system with a finite number of degrees of freedom. The
\ndegrees of freedom refer to the number of independent coordinates
\nnecessary to describe the motion of the system. In particular
\nsituations a single degree of freedom system can be an adequate
\nmodel for the real structure. Although the majority of structures
\ncannot be treated as SDOF systems, the measures specifying damping
\ncan be defined using a SDOF model without compromising the
\ngenerality of the definitions.<\/p>\n

Damping in structures may be categorised as either intrinsic,
\ni.e., within the material of the structure, or as the damping which
\ndepends upon other dissipative factors, such as friction in rivets
\nor bolts, or from lubrication (Reference 22). Damping also occurs
\nin a structure which is radiating sound, as vibrational energy is
\nlost in the surrounding medium rather than by dissipation in the
\nstructure. Material and radiation damping can be estimated
\ntheoretically more easily than other types of damping; in the case
\nof material damping prediction is based on the material properties
\nand for radiation damping from the geometrical and material
\nproperties of the structure. When the damping of a structure is
\nmeasured in most practical tests, it is the damping of all kinds
\nwhich is determined, including the material damping and, provided
\nthere is a surrounding fluid medium, radiation damping.<\/p>\n

The measures of damping which are most often used in dynamic
\nanalysis are: the viscous damping ratio (?), the specific damping
\ncapacity (?), the loss factor (?), the inverse quality factor
\n(Q\u20131<\/sup>), the logarithmic decrement (d) and, in the case of
\nmaterial damping, the tangent of the phase lag (?). and the ratio
\nof the loss modulus to the Young's modulus. Definitions of the
\nmeasures are introduced in the Item using examples of linear
\nmechanical models, such as Kelvin-Voigt (with viscous damper) and
\nhysteretic damping model (with hysteretic damper), especially
\napplicable to material damping. In ESDU Items information on
\ndamping is mostly provided in terms of the viscous damping ratio.
\nFor example, in Data Item No. 72005, \u2018The estimation of r.m.s.
\nstress in stiffened skin panels subjected to random acoustic
\nloading' (Reference 20), nomographs are used which are based on a
\nviscous damping ratio of 0.017, a value regarded as typical for
\naerospace structures, and, if a different value is used, a
\ncorrection factor is applied. The relationships between the
\ndifferent measures of damping are summarised in the Appendix A.<\/p>\n","protected":false},"excerpt":{"rendered":"

Introduction to Damping<\/b><\/p>\n\n\n\n\n
Published By<\/td>\nPublication Date<\/td>\nNumber of Pages<\/td>\n<\/tr>\n
ESDU<\/b><\/a><\/td>\n2009-05<\/td>\n48<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":557450,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[2675],"product_tag":[],"class_list":{"0":"post-557439","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-esdu","8":"first","9":"instock","10":"sold-individually","11":"shipping-taxable","12":"purchasable","13":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/557439","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/557450"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=557439"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=557439"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=557439"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}