Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session C7: Soft Matter I |
Hide Abstracts |
Chair: Clive Siviour, University of Oxford Room: Regency Ballroom F |
Monday, July 10, 2017 11:15AM - 11:45AM |
C7.00001: Dynamic Mechanical Testing Techniques for Cortical and Cancellous Bone Invited Speaker: Trevor Cloete Bone fracture typically occurs as an impact loading event (sporting accidents, vehicle collisions), the simulation of which requires in-depth understanding of dynamic bone behavior. Bone is a natural composite material with a complex multi length-scale hierarchical microstructure. At a macroscopic level, it is classified into hard/compact cortical bone and soft/spongy cancellous (trabecular) bone, though both are low-impedance materials relative to steels. Cortical bone is predominant in long bones, while in complex bone geometries (joints, flat bones) a cancellous bone core supports a thin cortical shell. Bone has primarily been studied at quasi-static strain rates ($\dot{\epsilon}<1\,s^{-1}$), with some dynamic studies ($300\,s^{-1}<\dot{\epsilon}<3000\,s^{-1}$), but rarely at intermediate strain rates (ISR) ($1\,s^{-1}<\dot{\epsilon}<100\,s^{-1}$). The data shows bone to be viscoelastic, which suggests that more dynamic and ISR data is required. Furthermore, bone exhibits quasi-brittle failure, with interrupted quasi-static tests revealing a strong microstructure dependence. However, bone specimens are typically destroyed during dynamic tests, leading to a lack of dynamic microstructural damage investigations. In this paper, a short overview of dynamic bone testing is presented to give context to the challenges of testing low impedance, strain-rate dependent, non-linear, visco-elastic-brittle materials. Recent state-of-the-art experimental developments in dynamic bone testing are reviewed, with emphasis on pulse shaping, momentum trapping and ISR testing. These techniques allow for dynamic bone testing at small strains and near-constant strain rates with intact specimen recovery. The results are compared to those obtained with varying strain rate tests. Interrupted dynamic test results with microstructural analysis of the recovered specimens are presented and discussed. The paper concludes with a discussion of the experimental and modeling challenges that lie ahead in the field of dynamic bone behavior. [Preview Abstract] |
Monday, July 10, 2017 11:45AM - 12:00PM |
C7.00002: New Platforms for Characterization of Biological Material Failure and Resilience Properties. Katherine Brown, Benjamin J. Butler, Thuy-Tien N. Nguyen, David Sorry, Alun Williams, William G. Proud Obtaining information about the material responses of viscoelastic soft matter, such as polymers and foams has, required adaptation of techniques traditionally used with hard condensed matter. More recently it has been recognized that understanding the strain-rate behavior of natural and synthetic soft biological materials poses even greater challenges for materials research due their heterogeneous composition and structural complexity. Expanding fundamental knowledge about how these classes of biomaterials function under different loading regimes is of considerable interest in both fundamental and applied research. A comparative overview of methods, developed in our laboratory or elsewhere, for determining material responses of cells and soft tissues over a wide range of strain rates (quasi-static to blast loading) will be presented. Examples will illustrate how data are obtained for studying material responses of cells and tissues. Strengths and weaknesses of current approaches will be discussed, with particular emphasis on challenges associated with the development of realistic experimental and computational models for trauma and other disease indications. [Preview Abstract] |
Monday, July 10, 2017 12:00PM - 12:15PM |
C7.00003: Investigation of Ballistic Penetration through Tibia Soft Tissue Simulant Thuy-Tien N Nguyen, Spyros D Masouros, Gareth R Tear, William G Proud High energy trauma events such as from explosions and ballistic weapons can cause severe damage to the human body. The resulting injuries are very complex and their mechanism is not fully understood. Secondary blast injuries, effectively ballistic traumas, to the extremities are commonly reported, especially to the tibia. The aim of this study is to quantify the effect of parameters such as projectile mass and velocity, and impact location on injury thresholds in the leg. The bones of the leg were set in biofidelic gelatin tissue simulant. A 32-mm-bore gas gun was used to launch a sabot carrying a carbon steel projectile 0.5 to 1.1 g in mass at the sample with speeds of 50 to 300 m/s. Penetration depth and impact velocity were recorded. The effect of different postures - such as standing and non-weight bearing – on injury were considered. The resulting injuries were scored clinically and their correlation with the various impact parameters was calculated. [Preview Abstract] |
Monday, July 10, 2017 12:15PM - 12:30PM |
C7.00004: Osteogenic differentiation of periosteum-derived stromal cells in blast-associated traumatic loading David R Sory, Harsh D Amin, Sara M Rankin, William G Proud One of the most recurrent medical complications resulting from blast trauma includes blast-induced heterotopic ossification. Heterotopic ossification refers to the pathologic formation of extraskeletal bone in non-osseous tissue. Although a number of studies have established the interaction between mechanics and biology in bone formation following shock trauma, the exact nature of the mechanical stimuli associated to blast-loading and their influence on the activation of osteogenic differentiation of cells remain unanswered. Here we present the design and calibration of a loading platform compatible with living cells to examine the effects of mechanical stress pulses of blast-associated varying strain rates on the activation of osteogenic differentiation of periosteum (PO) cells. Multiaxial compression loadings of PO cells are performed at different magnitudes of stress and ranges of strain rate. A proof of concept is presented so as to establish a new window to address fundamental questions regarding blast injuries at the cellular level. [Preview Abstract] |
Monday, July 10, 2017 12:30PM - 12:45PM |
C7.00005: Blast and Shock Mitigation Through the Use of Advanced Materials Susan Bartyczak, Lauren Edgerton, Willis Mock The dynamic response to low amplitude blast waves of four viscoelastic materials has been investigated: Dragonshield BC$^{\mathrm{TM}}$ and three polyurea formulations (P1000, P650, and a P250/1000 blend). A 40-mm-bore gas gun was used as a shock tube to generate planar blast waves, ranging from 1 to 2 bars, that impacted instrumented target assemblies mounted on the gas gun muzzle. Each target assembly consisted of a viscoelastic material sample sandwiched between two gauge assemblies for measuring wave velocity and input/output stresses. Each gauge assembly consisted of one polyvinylidene fluoride (PVDF) stress gauge sandwiched between two 3.25 inch diameter 6061-T6 aluminum discs. Impedance matching techniques were used on the stress measurements to calculate the stresses on the front and back of the samples. The shock velocity-particle velocity relationship, stress-particle velocity relationship, and blast attenuation for each material were determined. The experimental technique, analysis methodology, and results will be presented. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700