Issue 10 Volume 41 May 16, 2003

The static position of single leg stance is a generally accepted worst case scenario for hip joint loading. However, it is
essential in particular for investigations including temporal effects such as studies on fracture healing, fatigue, micromotion
and remodeling to examine the dynamic loading situation not only at a single moment in time, but during the complete range
of motion. In this study, a three-dimensional dynamic finite element model of the human femur during the gait cycle is
developed. A temporally varying hip joint reaction force distribution during walking and jogging is employed and a temporally
varying abductor muscles force is included while the distal end of the femur is constrained in translation only. The distribution
of the displacements and stresses throughout the femur during different instants of the gait cycle is obtained in both loading
conditions and compared. Also, an intramedullary prosthesis is nailed in the previous model and the femur prosthesis is
subjected to a similar type of loading. The results can be used to visualize the mechanical environment in the intact femur
during dynamic loading and compare it to that after total hip arthroplasty. Such knowledge is vital for surgical procedures,
healing processes as well as therapeutic regimes.
DTIC
Stress (Physiology); Joints (Anatomy); Prosthetic Devices; Gait; Running
20030033097 Defence Research and Development Canada, Ottawa, Ontario, Canada
Assessment of Motion Effects on the FPSO (Floating, Production, Storage and Offloading) Vessel Terra Nova
Cheung, Bob; Brooks, Chris J.; Hofer, Kevin; Oct. 2002; 48 pp.; In English
Report No.(s): AD-A410576; DRDC-TORONTO-TR-2002-144; No Copyright; Avail: CASI; A03, Hardcopy
Current oil and gas exploration requirements to exploit deeper water change the method of oil extraction. Floating
Production Storage and Off-loading (FPSO) vessels are increasingly being used to operate in these fields where the
environment can be very extreme. The Petro Canada Terra Nova Floating, Production, Storage, Offshore vessel (FPSO) is the
first of its kind built for operations on the Grand Banks at the Terra Nova field and is the first to operate in Canadian waters.
The crew on these vessels is expected to operate for as long as possible under extreme weather conditions within certain safety
margins. Seasickness and its after-effects, motion-induced fatigue and motion-induced interruptions remain a potential threat
to crewmembers at sea. Understanding the incidence, severity and the effects of seasickness on performance, can improve
effective scheduling and task assignment. This survey attempts to (1) define the incidence and severity of the symptom
complex of seasickness, motion-induced fatigue and task performance problems encountered on the Terra Nova FPSO vessel
and (2) to examine correlations (if any) between FPSO vessel motions, seasickness, motion-induced fatigue and task
performance, towards the development of recommendations to provide operations guidance to ameliorate seasickness and
improve comfort and performance in the environment described above. A questionnaire-based survey of motion effects
including sleep problems, symptoms and severity of seasickness and task performance was administered at various times
during 3-week offshore shifts. Ship motion data provided for this analysis was based on data gathered from the helideck (at
the bow of the FPSO vessel) motion analysis and was provided by the radio operator from the FPSO Offshore Installation
Office. Based on 911 questionnaires returned, problems reported for sleep disturbance and motion sickness symptoms were
slight to moderate.
DTIC
Motion Sickness; Ships
20030033114 Tongji Univ., Shanghai, China
An Analytical Method for Rolling Contact of Articular Cartilages in Diarthrodial Joint
Wu, Jianguo; October 25, 2001; 4 pp.; In English
Report No.(s): AD-A410609; No Copyright; Avail: CASI; A01, Hardcopy
An analytical method is presented to investigate the stresses and strains in the cartilage layers of diarthrodial joint under
rolling contact. Each cartilage layer in contact is assumed to be biphasic, composed of a linear elastic solid phase and
Newtonian viscous fluid, whereas the subchondral bone is simplified as a rigid body. The contact range of two cartilage layers
is discretized, where the surface tractions are piecewise given. A Galerkin-penalty method is applied to form the finite element
formulation for the cartilage layers. The surface tractions, stresses and strains in the cartilage layers are then obtained for each
time step with a numerical procedure of rolling contact. Results show that the interstitial fluid plays a fundamental role in the
distributions of the stresses and strains in the cartilage. The normal solid stress reaches its maximum on the cartilagesubchondral
bone interface. The coefficient of friction at the contact surface has a great effect on the tangential traction while
it has little effect on the normal traction. The difference of rolling velocity between the two cartilage layers has an increasing
effect on the tangential traction as the coefficient of friction increases.
DTIC
Bones; Cartilage; Galerkin Method; Joints (Anatomy); Rolling Contact Loads
150