A finite element and experimental analysis of energy absorbing systems under static and dynamic loading conditions

Knowledge of the behaviour of kinetic energy absorbers or impact attenuating devices is of paramount importance to design and research engineers involved in the automobile, aircraft, spacecraft, and nuclear industries. The main function of these devices is to minimise injury to personnel, to protect cargo that contain hazardous materials or to protect delicate structures from possible impact damage. Such industries require these devices to dissipate kinetic energy into an irreversible form and more importantly, in a controlled and desired manner. The performance of kinetic energy absorbers is significantly affected by various physical parameters such as material properties, mode of deformation and the nature of loading, with strain rate and inertial effects playing an important role due to high velocity impact. This work details the experimental and computational analysis of circular and oblong shaped kinetic energy absorbers subjected to quasi-static and dynamic lateral loading. The objective of this research was twofold; firstly, to design optimised kinetic energy absorbers which exhibit a desirable force-deflection response and secondly, to increase the specific energy absorbing capacity of such systems. The energy absorbers were in the form of a nested system consisting of a number of mild steel tubes of varying diameters assembled internally. The longitudinal axis of each tube was in parallel and an eccentric tube configuration was used. These systems were compressed laterally using three different devices: a flat platen, a cylindrical rod and a longitudinal line load indenter. It was found that the optimised designs for both the circular and oblong shaped devices exhibited very desirable features in terms of its force-deflection response. This was achieved by using a simple design modification which was incorporated into the optimised designs. Also, it was concluded that the specific energy absorption capacity of these nested systems can be increased notably by introducing external constraints which subject them to extra volumetric deformation. Both objectives were achieved using the finite element method, the results of which were validated using experimental techniques. It can be concluded that a new family of kinetic energy absorbers in the form of nested metallic systems have been designed which meet the objectives outlined and can thereby contribute to the literature in the field of kinetic energy absorbers

Anatomy of a Community-Level Fiscal Impact Model: FIT-4-NH.

Abstract: This paper describes the development of a fiscal impact tool for New Hampshire communities (HT -4-NH). FIT -4-NH belongs to a family of computergenerated fiscal impact assessment models designed to estimate the impacts to local government revenues and expenditures that result from economic changes. In the past, work in this area has centered on the completion of countylevel models for the midwestern states. FIT-4-NH is unique in that it was designed for rural community-level use in the northern New England region of the country

Economies of City Size: Per Capita Costs of Providing Community Services

Agricultural Economic

Reference to the index of the correspondence, personal records and miscellaneous lectures and talks of Edmund Morris Miller (1881-1964)

Edmund Morris Miller (1881-1964) C.B.E., M.A., D.Litt. (Melb.) was a librarian in the Public Library of Victoria from 1900 until 1913 when he was appointed Lecturer in Mental and Moral Science in the University of Tasmania. He was made Assoc. Prof. in 1925 and Professor in 1928. From 1933 to 1945 he served as Vice-Chancellor and also was Honorary Librarian from 1919 until 1945. The collection was deposited by Morris Miller on his retirement and augmented by donations from Mrs Miller and others in response to an appeal from the Library in 1967. The collection includes general correspondence received, mainly on literary and bibliographic topics predominately from 1955 to 1962, copies and drafts of letters sent, mainly about his literary research and publications, personal records, university lecture notes, typescripts of his various publications, newspaper cuttings and photographs

Libraries and Education

Edmund Morris Miller's book with sections on 'Libraries in Relation to Education', 'School Libraries and Reading', the University Library', and 'Schools and Libraries

High Power, Low Frequency Ultrasound: Meniscal Tissue Interaction and Ablation Characteristics

Abstract—This study evaluates high power low frequency ultrasound transmitted via a flat vibrating probe tip as an alternative technology for meniscal debridement in the bovine knee. An experimental force controlled testing rig was constructed using a 20 kHz ultrasonic probe suspended vertically from a load cell. Effect of variation in amplitude of distal tip displacement (242–494 mm peak-peak) settings and force (2.5–4.5 N) on tissue removal rate (TRR) and penetration rate (PR) for 52 bovine meniscus samples was analyzed. Temperature elevation in residual meniscus was measured by embedded thermocouples and histologic analysis. As amplitude or force increases, there is a linear increase in TRR (Mean: 0.9 to 11.2 mg/s) and PR (Mean: 0.08 to 0.73 mm/s). Maximum mean temperatures of 84.6C and 52.3C were recorded in residual tissue at 2 mm and 4 mm from the ultrasound probe-tissue interface. There is an inverse relationship between both amplitude and force, and temperature elevation, with higher settings resulting in less thermal damage.

Analysis of nested tube type energy absorbers with different indenters and exterior constraints

The present work presents both numerically and experimentally the quasi-static lateral compression of nested systems with vertical and inclined side constraints. The force-deflection response of mild steel short tubes compressed using two types of indenter’s is examined. The variation in response due to these indenters and external constraints are illustrated and how these can contribute to an increase the energy absorbing capacity of such systems. The implicit version of the Finite Element code via ANSYS is used to simulate these nested systems and comparison of results is made with those obtained in experiments and were found to be in good agreement