Biomechanics

Estimation of thrust of swimmer's hand using CFD

by Yohei Sato

"Co-authored with Takanori Hino"
"published in Proceedings of 2nd International Symposium on Aqua Bio-Mechanisms, Hawaii, 2003"
"Swimmer A is Ian Thorpe and Swimmer B is Pieter Van den Hoogenband, when Ian made the world record 1'44"05 in 9th FINA World Swimming Championships, 2001, Fukuoka, Japan"

A method to estimate thrust of swimmer’s hand
is established. An unsteady Navier-Stokes solver based onmore A method to estimate thrust of swimmer’s hand
is established. An unsteady Navier-Stokes solver based on
unstructured grid is employed to calculate a viscous flow
around a swimmer’s hand. Using this flow solver, a simple
unsteady motion and practical crawl strokes are simulated.
Results of the simple unsteady motion show the necessity of
unsteady CFD analysis. In case of crawl strokes,
hydrodynamic forces acting on hands of the worldchampion
swimmers are simulated.

Kinematic Plasticity during Flight in Fruit Bats: Individual Variability in Response to Loading

by Jose Iriarte-Diaz

PLOS One 7 (5): e36665
Iriarte-Diaz J, Riskin DK, Breuer KS & Swartz SM (2012)

All bats experience daily and seasonal fluctuation in body mass. An increase in mass requires changes in flight... more All bats experience daily and seasonal fluctuation in body mass. An increase in mass requires changes in flight kinematics to produce the extra lift necessary to compensate for increased weight. How bats modify their kinematics to increase lift, however, is not well understood. In this study, we investigated the effect of a 20% increase in mass on flight kinematics for Cynopterus brachyotis, the lesser dog-faced fruit bat. We reconstructed the 3D wing kinematics and how they changed with the additional mass. Bats showed a marked change in wing kinematics in response to loading, but changes varied among individuals. Each bat adjusted a different combination of kinematic parameters to increase lift, indicating that aerodynamic force generation can be modulated in multiple ways. Two main kinematic strategies were distinguished: bats either changed the motion of the wings by primarily increasing wingbeat frequency, or changed the configuration of the wings by increasing wing area and camber. The complex, individual-dependent response to increased loading in our bats points to an underappreciated aspect of locomotor control, in which the inherent complexity of the biomechanical system allows for kinematic plasticity. The kinematic plasticity and functional redundancy observed in bat flight can have evolutionary consequences, such as an increase potential for morphological and kinematic diversification due to weakened locomotor trade-offs.

Exploring how anthropometric, vehicle and workplace factors influence whole-body vibration exposures during on-farm use of a quad bike

by Daniel Ribeiro

Milosavljevic, S.; Mani, R.; Ribeiro, D. C.; Vasiljev, R.; Rehn, B. (2012).  International Journal of Industrial Ergonomics, 42, 392-396

The primary aim of this study is to determine whether a combination of body height, terrain and vehicle mechanical... more The primary aim of this study is to determine whether a combination of body height, terrain and vehicle mechanical factors confound for the effect of body mass on WBV exposure while using a quad bike under normal rural working conditions. A seat pad mounted triaxial accelerometer and data logger recorded full work day vibration and shock data from 130 New Zealand rural workers. Personal, vehicle and workplace characteristics were gathered using a modified version of the Whole Body Vibration Health Surveillance Questionnaire. Whole-body vibrations were analysed in accordance with the ISO 2631-1 and ISO 2631-5 standards and it is presented as one hour vibration dose value in the Z-direction (1 h VDVZ). Body mass did not demonstrate any significant bivariate association (P > 0.20) with 1 h VDVZ. However BMI, body height, vehicle weight, sheep farm, dairy farm, 2 shock absorber solid axle rear suspension, flat farmland and engine capacity (cc) all demonstrated threshold bivariate associations (P _ 0.20) with 1 h VDVZ. Body mass, body height, 2 shock absorber solid rear axle suspension, and working on a sheep farm created the strongest multiple regression model explaining 16% of variance in VDVZ. Relevance to industry: The influence of driver’s body mass on vibration exposure is strongly influenced by work environment and vehicle mechanical factors and this should be taken in to consideration for research that explores exposures and/or designing seating and suspension systems to attenuate vibration exposures in small on-farm vehicles.

Traumatic pneumothorax sustained via fine-wire electromyography insertion at the shoulder

by Daniel Ribeiro

Wassinger, C. ; Osborne, H. ; Ribeiro, D. C. (2011). Physiotherapy, 97, 4, 357-359

Water collection and drinking in Phrynocephalus helioscopus: a possible condensation mechanism

by Kurt Schwenk

Water collection and drinking in Phrynocephalus helioscopus: a possible condensation mechanism

by Kurt Schwenk

A simple, inexpensive system for digital particle image velocimetry (DPIV) in biomechanics

by Kurt Schwenk

3D Analysis of the Forearm Rotational Efficiency Variation in Humans

by Pere Ibáñez-Gimeno

Goss-Sampson, M., Robbins, D., Matharoo, J., Filingeri, D. (2011). The Effects of powerBIKETM on Cyclical Muscle Activation Patterns. The British Association of Sport and Exercise Sciences (BASES) Annual Conference, 6-8th Sept, 2011, University of Essex, UK.

by Davide Filingeri

Simone, S. V., Filingeri, D., Gariffo, E., Thomas, E., Moro, T., Battaglia, G., Bellafiore, M., Paoli, A., Bianco, A., Palma, A. (2011) Effects of a constant and incremental workload training protocol on upper body strength gains. Journal of Sports Medicine and Physical Fitness. 51 (Suppl.1 to No. 3): 39.

by Davide Filingeri

Changes in knee joint biomechanics following balance and technique training and a season of Australian football

by Alasdair Dempsey

Donnelly CJ, Elliott BC, Doyle TLA, Finch CF, Dempsey AR, Lloyd DG. Changes in knee joint biomechanics following balance and technique training and a season of Australian football. British Journal of Sports Medicine. Online First 30 April 2012 doi:10.1136/bjsports-2011-090829

Purpose Determine if balance and technique training (BTT) implemented adjunct to normal Australian football (AF)... more Purpose Determine if balance and technique training (BTT) implemented adjunct to normal Australian football (AF) training reduces external knee loading during sidestepping. Additionally, the authors determined if an athlete's knee joint kinematics and kinetics change over a season of AF.

Methodology Eight amateur-level AF clubs (n=1,001 males) volunteered to participate in either 28 weeks of BTT or a ‘sham’ training (ST) adjunct to their normal preseason and regular training. A subset of 34 athletes (BTT, n=20; ST, n=14) were recruited for biomechanical testing in weeks 1–7 and 18–25 of the 28-week training intervention. During biomechanical testing, participants completed a series running, preplanned (PpSS) and unplanned sidestepping (UnSS) tasks. A linear mixed model (α=0.05) was used to determine if knee kinematics and peak moments during PpSS and UnSS were influenced by BTT and/or a season of AF.

Results Both training groups significantly (p=0.025) decreased their peak internal-rotation knee moments during PpSS, and significantly (p=0.022) increased their peak valgus knee moments during UnSS following their respective training interventions.

Conclusions BTT was not effective in changing an athlete's knee joint biomechanics during sidestepping when conducted in ‘real-world’ training environments. Following normal AF training, the players had different changes to their knee joint biomechanics during both preplanned and unplanned sidestepping. When performing an unplanned sidestepping task in the latter half of a playing season, athletes are at an increased risk of ACL injury. The authors therefore recommend both sidestepping tasks are performed during biomechanical testing when assessing the effectiveness of prophylactic training protocols.

Nest-building orangutans demonstrate engineering know-how to produce safe, comfortable beds

by Adam van Casteren

Adam van Casteren, William I. Sellers, Susannah K. S. Thorpe, Sam Coward, Robin H. Crompton, Julia P. Myatt, and A. Roland Ennos

PNAS (2012) 109 6873-6877

Nest-building orangutans must daily build safe and comfortable nest structures in the forest canopy and do this... more Nest-building orangutans must daily build safe and comfortable nest structures in the forest canopy and do this quickly and effectively using the branches that surround them. This study aimed to investigate the mechanical design and architecture of orangutan nests and determine the degree of technical sophistication used in their construction. We measured the whole nest compliance and the thickness of the branches used and recorded the ways in which the branches were fractured. Branch samples were also collected from the nests and subjected to three-point bending tests to determine their mechanical properties. We demonstrated that the center of the nest is more compliant than the edges; this may add extra comfort and safety to the structure. During construction orangutans use the fact that branches only break half-way across in “greenstick” fracture to weave the main nest structure. They choose thicker branches with greater rigidity and strength to build the main structure in this way. They then detach thinner branches by following greenstick fracture with a twisting action to make the lining. These results suggest that orangutans exhibit a degree of technical knowledge and choice in the construction of nests.

Effect of Pretension and Suture Needle Type on Mechanical Properties of Acellular Human Dermis Patches for Rotator Cuff Repair

by Sambit Sahoo

Sahoo S, Greeson CB, McCarron JA, Milks RA, Aurora A, Walker E, Iannotti JP, Derwin KA. Journal of Shoulder and Elbow Surgery. 2011 (In press)

How is dog gait affected by natural rough terrain?

by Michelle Reeve

Meeting abstract presented by Andrew J. Spence at SICB 2012.
WILSHIN, Simon; HAYNES, G. Clark; REEVE, Michelle; REVZEN, Shai; SPENCE, Andrew J.*; Integrative and Comparative Biology 52:198-198.
Royal Veterinary College; University of Pennsylvania; Royal Veterinary College; University of Pennsylvania; Royal Veterinary College aspence@rvc.ac.uk

In nature legged animals depend on locomotion over uneven terrain for survival and reproduction. One way in which... more In nature legged animals depend on locomotion over uneven terrain for survival and reproduction. One way in which animals may optimize their locomotor behaviour for this task is by adjusting the relative timing of their leg recirculation, or gait. Therefore, we asked how the relative leg timing of quadrupeds changes during locomotion over natural, uneven terrain, and compared this to our idealised notions of the walk, trot and gallop. Five male dogs of shoulder height 522.0 ± 62.6 mm (mean ± s.d.) and body mass 20.0 ± 2.5 kg (mean ± s.d.) were trialled at nominal walk, trot, and gallop speeds over flat and uneven terrain. Mean perturbation size on uneven terrain was 54.8 ± 44.6 mm versus 4.2 ± 3.1 mm on flat. Dogs were fitted with a wirelessly synchronized suite of five sensors, comprised of Global Position System and inertial measurement units. One device was attached to the proximal-most segment of each leg, and a fifth on the midline of the back at the front legs. Raw sensor data were used to compute animal speed, position, and a continuous estimate of leg phases. The centroids of relative leg phase (averaged across time within each stride), describing the gait used by the dog on each terrain at each nominal gait speed, were significantly different on the rough terrain (linear mixed-model; n=5 dogs, p<0.05). At walking speeds on the rough terrain, dog gait moves towards the trot. Averages and distances between gaits in relative leg phase space do not account for the dynamical and geometric structure of these phase variables, however. Theoretical developments required to handle these data will be discussed. To explain why we observe these changes in dog gait, we propose experiments in a physical model, the robot XRL.

Upper extremity joint stresses during walker-assisted ambulation in post-surgical patients Estresse articular no membro superior durante marcha assistida por andador em pacientes pós-cirúrgicos

by Kevin J. McQuade

Modeling the human mandible under masticatory loads: which input variables are important?

by Flora Gröning

2012, Anatomical Record, DOI: 10.1002/ar.22455

Finite element analyses (FEA) that have simulated masticatory loadings of the human mandible differ significantly with... more Finite element analyses (FEA) that have simulated masticatory loadings of the human mandible differ significantly with regard to their basic input variables such as material properties, constraints, and applied forces. With sensitivity analyses it is possible to assess how the choice of different input values and the degree of model simplification affect FEA results. However, published FEA studies are rarely accompanied by sensitivity analyses so that the robusticity of their results is impossible to assess. Here, we conduct a sensitivity analysis with an FE model of a human mandible to quantify the relative importance of several modeling decisions: (1) the material properties assigned to the cancellous bone tissue; (2) the inclusion or not of the periodontal ligament; (3) the constraints at the joints and bite point; and (4) the orientation of applied muscle forces. We study the effects of varying these properties by analysing the strain magnitudes and directions across the model surface. In addition, we perform a geometric morphometric analysis of the deformation resulting from the loading of each model. The results show that the effects of altering the different model properties can be significant and that most effects are potentially large enough to cause problems for the biological interpretation of FEA results. We therefore recommend that researchers conduct more sensitivity analyses than at present to assess the robusticity of their FEA results and their biological conclusions.

Padrões de referência da pressão plantar no movimento do Cão da Serra da Estrela

by Carla Cruz

Foot pressure reference values for the Estrela Mountain Dog locomotion

Neste trabalho caracteriza-se em termos de pressão plantar o movimento do Cão da Serra da Estrela no andamento “Marcha... more Neste trabalho caracteriza-se em termos de pressão plantar o movimento do Cão da Serra da Estrela no andamento “Marcha Semelhante ao Pacing” (“Ambladura”). Foram analisados 11 cães Serra da Estrela, isentos de displasia da anca e sem sinais visíveis de patologias que afectem o movimento, recorrendo a um sistema de plataformas de pressão plantar (RSSCAN) com 2 metros de comprimento. Para a caracterização do movimento do Serra da Estrela foi desenvolvido um software de apoio que permite a análise cinética, determinando-se vários parâmetros espaciais, temporais e cinéticos relativos ao movimento do Cão da Serra da Estrela, que poderão servir de referência em futuros estudos sobre patologias do aparelho locomotor.

A Simple, Inexpensive System for Digital Particle Image Velocimetry (DPIV) in Biomechanics

by Bill Ryerson

Palaeobiology of Euowenia grata (Marsupialia: Diprotodontinae) and its Presence in Northern South Australia

by Aaron Camens

Recovery of a specimen of Euowenia grata (De Vis, 1887) from mid Pliocene sediments of the Tirari Formation on the... more Recovery of a specimen of Euowenia grata (De Vis, 1887) from mid Pliocene sediments of the Tirari Formation on the bank of the Warburton River in the Lake Eyre Basin provides the first recorded account of this species in South Australia. The specimen comprises a partial skull including left and right premaxillae, maxillae, and left zygomatic arch, along with an almost complete upper dentition (missing the left I2). An articulated hind leg and pes found downstream at the same stratigraphic level, as well as both fore- and hind-feet of a single individual, are also referred to E. grata and represent the first postcranial material assigned to the species. A reconstruction of the pes indicates that much more of the body weight was borne by the tarsus in this species than in plesiomorphic diprotodontids, such as Nimbadon Hand et al., 1993, or Ngapakaldia Stirton, 1967, although E. grata does not exhibit the more extreme enlargement of the tarsus seen in graviportal Pleistocene diprotodontids. E. grata is found here also to be the only known Australian marsupial, extant or extinct, to exhibit fusion of all three cuneiform bones in the tarsus. We suggest that the diprotodontine hind limb and pes had evolved graviportal adaptations in the Pliocene as well as in the Pleistocene members. We also suggest that E. grata may have been able to rear up against trees while browsing.

The locomotor musculature of basal ornithischian dinosaurs.

by Susannah Maidment