Society For Experimental Mechanics Research Articles

A Comprehensive Study on Detection of Hidden Delamination Damage in a Composite Plate Using Curvatures of Operating Deflection Shapes

The aim of this work is to investigate the accuracy and sensitivity of a continuously scanning laser Doppler vibrometer (CSLDV) for detection of hidden delamination damage in composite plates. Some work on using a CSLDV for detection of damage in aluminum beams and plates has been done by the authors. The current work is related to a worldwide round robin study sponsored by the Society of Experimental Mechanics. The main difference between the current work and previous work is that the damaged composite plate was provided by the organizer of the round robin study instead of being made by the authors. Hence, the authors have no information about locations of the damage, which means this is more like a blind test. The most significant advantage of using a CSLDV for vibration measurement of a structure is that a spatially dense operating deflection shape (ODS) of the structure can be obtained and further used to calculate the curvature of the ODS (CODS). A comprehensive study to detect the hidden damage in the composite plate by using the first seven CODSs from the corresponding ODSs of the plate is conducted. The study shows that different CODSs have different sensitivities to local anomaly induced by the damage and only two of the seven CODSs can be used to detect the locations of the hidden damage.

The Old and New… A Narrative on the History of the Society for Experimental Mechanics

The field of Experimental Mechanics has evolved substantially over the past 100 years. In the early years, the field was primarily comprised of applied physicists, civil engineers, railroad engineers, and mechanical engineers. The field defined itself by those who invented, developed, and refined experimental tools and techniques, based on the latest technologies available, to better understand the fundamental mechanics of materials and structures used to design many aspects of our everyday life. What the early experimental mechanician measured, observed, and evaluated were things like stress, strain, fracture, and fatigue, to name a few, which remain fundamental to the field today. This book guides you through a chronology of the formation of the Society for Experimental Mechanics, and its ensuing evolution. The Society was founded in 1935 by a very small group of individuals that understood the value of creating a common forum for people working in the field of Applied Mechanics of Solids, where extensive theoretical developments needed the input of experimental validation. A community of individuals who—through research, applications, sharp discussion of ideas—could fulfill the needs of a nation rapidly evolving in the technological field. The founders defined, influenced, and grew the field of what we now call Experimental Mechanics. Written as a narrative, the author describes, based on input from numerous individuals and personal experiences, the evolution of the New England Photoelasticity Conference to what we know today as the Society for Experimental Mechanics (SEM). The narrative is the author's perspective that invites members of the Society to contribute to the story by adding names of individuals, institutions, and technologies that have defined the Society over the past 75 years. Many of the key individuals who greatly influenced the advancement of the field of Experimental Mechanics are mentioned. These individuals are, in many ways, the founders of the field who have written textbooks, brought their teaching leadership and experiences to the classroom, worked on the Apollo project, and invented testing, evaluation, and measurement equipment that have shaped the fields of engineering. SEM's international membership is highly represented by those in academia, as you will read, although there has always been a powerful balance and contribution from industry and research organizations across the globe. The role of the experimental mechanician is defined, in many ways, through the individual legacies shared in the following pages….legacies that define the past and create the foundation for what is now and what is to come.

Dynamic Tensile Experimental Techniques for Geomaterials: A Comprehensive Review

This review article is dedicated to the Dynamic Behavior of Materials Technical Division for celebrating the 75th anniversary of the Society for Experimental Mechanics (SEM). Understanding dynamic behavior of geomaterials is critical for analyzing and solving engineering problems of various applications related to underground explosions, seismic, airblast, and penetration events. Determining the dynamic tensile response of geomaterials has been a great challenge in experiments due to the nature of relatively low tensile strength and high brittleness. Various experimental approaches have been made in the past century, especially in the most recent half century, to understand the dynamic behavior of geomaterials in tension. In this review paper, we summarized the dynamic tensile experimental techniques for geomaterials that have been developed. The major dynamic tensile experimental techniques include dynamic direct tension, dynamic split tension, and spall tension. All three of the experimental techniques are based on Hopkinson or split Hopkinson (also known as Kolsky) bar techniques and principles. Uniqueness and limitations for each experimental technique are also discussed.

DIC Challenge: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

With the rapid spread in use of Digital Image Correlation (DIC) globally, it is important there be some standard methods of verifying and validating DIC codes. To this end, the DIC Challenge board was formed and is maintained under the auspices of the Society for Experimental Mechanics (SEM) and the international DIC society (iDICs). The goal of the DIC Board and the 2D–DIC Challenge is to supply a set of well-vetted sample images and a set of analysis guidelines for standardized reporting of 2D–DIC results from these sample images, as well as for comparing the inherent accuracy of different approaches and for providing users with a means of assessing their proper implementation. This document will outline the goals of the challenge, describe the image sets that are available, and give a comparison between 12 commercial and academic 2D–DIC codes using two of the challenge image sets.

Experimental Techniques: Developments, Applications and Tutorials in Experimental Mechanics Techniques

We are excited to re-introduce Experimental Techniques (ET) as the flagship applications journal of the Society for Experimental Mechanics (SEM) in association with our new publisher Springer. We wish to invite you to submit your best work on developments, applications and tutorials in the field of experimental mechanics to the journal at www. editorialmanager.com/exte and to help in getting the word out to your colleagues at http://springer.com/40799.

Journal of Dynamic Behavior of Materials: A New Forum for Knowledge Exchange on Dynamic Material Response, High Strain-Rate Effects, Shock, and Materials Under Extreme Loading

We are excited to introduce the Journal of Dynamic Behavior of Materials (JDBM) as the new journal of the Society for Experimental Mechanics (SEM). We wish to invite you to submit your best work on the study of the dynamic behavior of materials to the journal and help in getting the word out to your colleagues. Information on the journal can be found at http://springer.com/40870. The field of dynamic behavior of materials is undergoing a revolution with increasing interdisciplinary focus and unprecedented new level of diagnosis at the bench scale and numerous user facilities. Classic loading techniques including split Hopkinson pressure (Kolsky) bar, gas/ powder guns, and high-explosives are being pushed to increased levels of precision, linked with new and novel diagnostics enabling previously unattainable levels of in situ measurement combined with advanced high resolution and three-dimensional post-mortem observation. National User Facilities are enhancing their capacities for studying materials in extremes with new facilities being developed ranging from SLAC’s Linac Coherent Light Source, the Dynamic Compression Sector at the Advanced Photon Source at Argonne National Laboratory, the Z-Machine at Sandia National Laboratories, the National Ignition Facility at Lawrence Livermore National Laboratory, and Matter-Radiation Interactions in Extremes at Los Alamos National Laboratory. An exciting collaboration at GSI in Darmstadt is incorporating expertise from pRad and LANSCE at Los Alamos National Laboratory in the USA and the Institute for Theoretical and Experimental Physics in Russia using the PRIOR microscope with great potential for studying dynamic materials processes. The Diamond Light Source located at the Harwell Science and Innovation Campus in the UK has been offering great levels of postmortem investigation of damage from dynamic loading. Exciting capabilities exist at these and other facilities around the world to advance the state-of-the-art for studies of dynamic behavior of materials. Advances in modeling & simulation of dynamic loading and material response have paralleled these experimental advances. Continued evolution in computing hardware is enabling calculations with extraordinary fidelity in representation of highly coupled complex physics. Great advances have been made in density functional theory, molecular dynamics, and dislocation dynamics based material models. Simulations based on these theories have historically had to be performed at very high strain-rates and in very short time and length scales. Advances in these models and the hardware on which these simulations are performed have brought them into line with the regimes of many platforms for dynamic experiments. New theories and models of material behavior are being developed to take advantage of understanding material at the mesoscale. Continuum level constitutive models are being proposed and developed with greater levels of physical underpinning and predictive ability. The state-of-the art in modeling & simulation and experiments along with the interdisciplinary approach to modern science and engineering have lead to significant payoff from hybrid experimental-computational approaches. Advances in simulation are enabling the development and optimization of experiments, with better understanding of the underlying physics and data capture. Conversely, advances in experimentation are pushing better models, codes, and simulations. The JDBM offers a single source to bring this broad, vibrant international community together. This peer E. N. Brown (&) Los Alamos National Laboratory, Los Alamos, NM 87545, USA e-mail: en_brown@lanl.gov

米国実験力学会秋季講演会 (SEM Fall 2014)および集中荷重とその影響に関する国際会議に参加して

米国実験力学会秋季講演会 (SEM Fall 2014)および集中荷重とその影響に関する国際会議に参加して

Particle-based numerical modeling of AE statistics in disordered materials

We present some numerical simulations of AE due to damage propagation in disordered materials under compression and bending. To this purpose, the AE cumulative number, the time frequency analysis and the statistical properties of AE time series will be numerically simulated adopting the so-called “particle method strategy” (Cundall in Proceedings ISRM Symp., Nancy, France, vol. 2, pp. 129–136, 1971). The method provides the velocity of particles in a set simulating the behavior of a granular system and, therefore, is suitable to model the compressive wave propagation and acoustic emission (corresponding to cracking) in a solid body. The numerical simulations (Abe et al. in Pure Appl. Geophys. 161:2265–2277, 2004) correctly describe the compression test in terms of mean stress-strain response and crack pattern (Invernizzi et al. in Proceedings of the SEM annual conference, Society for Experimental Mechanics Inc., USA, SEM Annual Conference, Indianapolis, Indiana, USA, June 7–10, 2010). The size effects on the peak compressive strength and on the AE count are correctly reproduced. In addition, the amplitude distribution (b-value) and temporal evolution of AE events due to cracking, crucial for the evaluation of damage and remaining lifetime, were simulated and result in agreement with the experimental evidences.

Celebrating 50 Years of Experimental Mechanics

This year, Experimental Mechanics celebrates its 50th anniversary. The Journal was launched in January of 1961 by the then Society for Experimental Stress Analysis (SESA) now the Society for Experimental Mechanics (SEM). Benjamin J. Lazan, who is credited as the individual most responsible for the creation of the Journal, wrote an editorial in the first issue of Experimental Mechanics where he articulated the reasons for the creation of the journal. He pointed out that the new journal was the result of the society growth, the broader realm of experimental mechanics, and the role of experimental studies in verification and improvement of theory. In his visionary editorial, Lazan wrote “the solution of the increasingly complex engineering problems must rely more and more on experimental mechanics studies to indicate limitations in current theories, to formulate more realistic and general, yet simple, assumptions required for developing new theories, and later to check the compatibility of these new theories with still newer engineering situations or simulations thereof.”

Emerging Methods in Mechanical Behavior

Over the week of March 9–13, 2008, at the TMS Annual Meeting in New Orleans, Louisiana, a symposium was held on the topic of “Emerging Methods in Mechanical Behavior.” While this topic is a common theme in the Society for Experimental Mechanics’ meetings, this particular symposium was somewhat unusual because the host venue, TMS, is a materials society rather than a mechanics society. The TMS meeting holds symposia ranging from aluminum refining to phase transformations. A subset of materials scientists specialize in understanding the mechanical properties of materials. It is this group of researchers that the symposium had targeted: metallurgists, materials scientists, and mechanical engineers who are developing or employing new techniques to gain insight into the mechanical behavior of materials. Materials Scientists typically come from a background that is strong in advanced characterization tools. For this reason, it is no surprise that this symposium on ‘Emerging Methods in Mechanical Behavior’ was laced with the quantitative application of characterization techniques in materials mechanics. Based on the contributions to this symposium, it is clear that diffraction techniques are expanding as a tool in experimental mechanics. While conventional x-ray diffraction has been used for decades as in the measurement of residual stresses, recently developed diffraction methods are becoming increasingly prevalent, including electron backscattered diffraction (also known as orientation imaging microscopy), synchrotron microdiffraction, and neutron diffraction. New microscopy techniques are also becoming prevalent. The dual-beam focused ion beam tool, which has emerged as a workhorse research tool in materials science over the past decade, permits microdissection, microwelding, ion channeling imaging, and many other creative new approaches to interrogation. Quantitative in-situ loading stages in scanning and transmission electron microscopies enable the connection between mechanical response and microscale evolution. In-situ imaging is providing valuable insight into nanoindentation and micropillar compression experiments. Another significant advance in quantitative experimental mechanics over the past decade has been the proliferation of digital image correlation (DIC) techniques. This surface deformation and strain mapping capability provides a tool for experimental mechanics that is loosely analogous to the advent of the finite element method for computational mechanics. Early applications of DIC were in the area of structural mechanics of lab-scale components. However, it is now clear that the DIC algorithm can also have applicability at the microscale through atomic force and scanning electron microscopies. Microscale DIC brings a powerful new tool to understand mechanical behavior at the microstructural scale. As shown in the collection of papers that are represented in this Special Issue of Experimental Mechanics, these emerging advanced characterization techniques are now providing crucial new insights into the mechanical behavior of materials. B.L. Boyce (*, SEM member) Sandia National Laboratories, Albuquerque, NM, USA e-mail: blboyce@sandia.gov

A FOLDED PENDULUM ISOLATOR FOR EVALUATING ACCELEROMETER PERFORMANCE

Author's manuscript version. the final published version is available from the publisher via DOI: 10.1111/j.1747-1567.2008.00364.x. © 2009, Society for Experimental Mechanics

Editorial

Editorial

Technical Note: Theoretical Analysis and Digital Photoelastic Measurement of Circular Disks Subjected to Partially Distributed Compressions

-The disk in diametral compression has been quoted most frequently on developing conventional/digital photoelasticity to illustrate new theories and experimental techniques for several decades. Theoretically, the compression as a concentrated force is more conducive to analysis, but it is impossible to achieve such loading condition experimentally. The distributed compression on a finite area at rim is relatively closer to actual testing and it is complicated to seek an analytical solution. In this paper, we extend the work of Hondros to derive the full-field stress distribution of disk subjected to diametrai distributed compression in an explicit functional form. The principal stress difference and principal stress orientation related to isochromatic and isoclinic fringes, respectively, are also expressed in a simple closed form. The maximum shear stress for the whole disk and the validity of using isochromatic fringes to interpret the maximum shear stress are discussed in detail. The isoclinic fringes are compared with theory, and the fringe multiplication isochromatic is compared with simulated image. All of the comparisons are in good agreement with respect to full field. KEY WORDS--Disk, distributed compression, digital photoelasticity, isochromatics, isoclinics, principal stress Introduction The problem of a circular disk subjected to concentrated forces applied at its boundary is frequently used in classical elasticity either to illustrate theories or to estimate experimental data. The stress analysis of the circular disk has been discussed by many authors. 1-4 However, the actual loads in an experiment are not concentrated but distributed over finite portions of the disk. Sanford 5 proposed a method to conversely calculate the isochromatic fringe order from Frochet's full-field solution by employing a least-squares method. Berghaus 6 presented a method combining finiteelement results with photoelastic data to estimate the fullfield distribution of stress. Haake et al. 7 presented a photoelastic device containing a quarter-wave plate and a polarizer to generate six different angular orientations and came up with six images using a CCD. The experiment of a disk in diametral compression is easy to conduct. In addition, the analytical solution of the fullfield stress can be used as a theoretical reference to check the experimental results. However, the problem of the disk in distributed diametral compression is more difficult to analyze than that with concentrated forces. Hondros 8 obtained the full-field stresses in a series solution by using the series expansion technique and applied these solutions to evaluate the Young's modulus and Poisson's ratio of concrete by measuring strain. Instead of using a series solution for full-field stresses, in this paper we continue and extend the work of Hondros to successfully obtain an analytical solution in an explicit form which can provide a full-field sampling capability as well as in-depth theoretical comparisons. Concise mathematical forms are also provided for principal stress orientation and maximum shear stress. Instead of operating a traditional large-sided photoelasticscope, a compact optic system using a He-Ne laser as a light source is installed on an optic bench to obtain the experimental results for the testing of the disk in diametral distributed compression. Full-field comparisons of isochromatic/isoclinic fringes between testing and theory are presented. The validity of using isochromatic fringes to interpret the maximum shear stress for disks subjected to partially distributed compression is discussed in detail. Full Field Analytical Solutions for Disks in Partially Distributed Compressions Consider a circular disk loaded by two diametrically opposing distributed compressive forces located on the top and bottom of the disk. The geometric configuration of this problem is shown in Fig. 1. Hondros used a polar coordinate system to present the full-field stresses in a series solution and the results are expressed as follows: (YF 2p e~ + ~ 1 1 p2 n=l 0 2n-2 sin 2ne~ cos 2nO} (1) K-M. Hung was a Graduate Stttdent and C.-C. Ma (ccma@nm.edu.tw) & a Professor, Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan 10617, Republic of China. K.-M. Hung now is an Associate Professor, Hwa-Hsia College of Technology and Commerce, Tripei, Taiwan, 23554, Republic of China. Original manuscript submitted." December 7, 2001. Final manuscript received." January 9, 2003. c ~ 0 = c~l 1 + 02 n=l p 2n-2 sin 2nc~ cos 2nO} (2) 216 9 VoL 43, No. 2, June 2003 9 2003 Society for Experimental Mechanics

Stress wave scattering in concrete: simple finite element model investigation : Fancher, N.B. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 256–266. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Stress wave scattering in concrete: simple finite element model investigation : Fancher, N.B. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 256–266. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Nondestructive analysis of microcracking in concrete : Luong, M.P. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 199–217. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Nondestructive analysis of microcracking in concrete : Luong, M.P. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 199–217. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Fuzzy cluster analysis and comprehensive evaluation of concrete quality with ultrasonic multi-parameters : Ju-hong, H.; Wei-du, L. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 267–276. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Fuzzy cluster analysis and comprehensive evaluation of concrete quality with ultrasonic multi-parameters : Ju-hong, H.; Wei-du, L. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 267–276. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Structural integrity evaluation of concrete piles from stress wave measurements : Hussien, M.; Morgano, M. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 391–408. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Structural integrity evaluation of concrete piles from stress wave measurements : Hussien, M.; Morgano, M. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 391–408. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Comparison between optical microscopy and scanning acoustic microscopy for detecting flaws in concrete : Tittmann, B.R.; Aligizaki, K.K.; Gordon, G.A. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 550–558. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Comparison between optical microscopy and scanning acoustic microscopy for detecting flaws in concrete : Tittmann, B.R.; Aligizaki, K.K.; Gordon, G.A. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 550–558. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

A survey of existing and new approaches for the generation of stress waves in concrete : Popovics, J.S.; Rose, J.L.; Popovics, S.; Newhouse, V.L.; Lewin, P.; Bilgutay, N. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 335–352. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

A survey of existing and new approaches for the generation of stress waves in concrete : Popovics, J.S.; Rose, J.L.; Popovics, S.; Newhouse, V.L.; Lewin, P.; Bilgutay, N. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 335–352. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Frequency spectra and ultrasonic pulse attenuation analyses for the assessment of damages in concrete : Bocca, P.; Rosa, G. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 218–227. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429

Frequency spectra and ultrasonic pulse attenuation analyses for the assessment of damages in concrete : Bocca, P.; Rosa, G. International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn, Michigan (United States), 9–11 Jun. 1993. pp. 218–227. Society for Experimental Mechanics, Inc., (1993) ISBN 10912053429