Wyniki wyszukiwania - BazTech

1

Rib kinematics analysis in oblique and lateral impact tests

Jastrzębski Dominik, Perz Rafał

Acta of Bioengineering and Biomechanics

|

2020

|

Vol. 22, no. 1

135--141

EN

Understanding thorax kinematics and rib breaking mechanisms in conditions of oblique and lateral impact is crucial in safety systems development. To increase knowledge level on this subject, simulation and experimental tests are necessary. The purpose of this study was to obtain single rib kinematics in the case of oblique and lateral impact conditions using numerical simulation approach. Methods: Two impact tests using human body model of a 50th percentile man (THUMS v4.0.1 AM50) were performed in LS-Dyna R7.1.1. Impactor was a rigid cylinder with a diameter of 152 mm, and velocity equal to 6.7 m/s. Impact angle measured to sagittal plane was 30 and 90°, respectively in oblique and lateral impact case. Results: Kinematics of ribs from 3rd to 6th were analyzed. Results shown significant similarities between oblique impact and kinematics of ribs tested in frontal impact conditions in the literature, with maximal costochondral joint displacement relatively to costovertebral joint varying from 65.4 mm (3rd rib) to 82.0 mm (5th rib). Deformation of rib in lateral impact conditions was different than during oblique impact test, with distinctive “flattening” approximately in the middle of the rib. Maximal relative displacement varies from 16.4 mm (6th rib) to 26.6 mm (5th rib) and its location depends on the analyzed rib. Conclusions: Oblique impact scenario may be simulated for the single rib on an experimental way using set-up of the frontal impact. Experimental simulation of the lateral impact for the single rib should not use the same set-up, as the kinematics analysis showed significant differences between simulated cases.

2

The influence of a thoracolumbosacral orthosis on gait performance in healthy adults during walking

Van Criekinge T., Truijen S., Hallemans A., Saeys W.

Acta of Bioengineering and Biomechanics

|

2018

|

Vol. 20, no. 4

15--21

EN

Since the thorax and pelvis are primary determinants of normal and pathological walking, it is important to know how gait performance is influenced when the trunk is constraint. The objective of this study is to investigate the effect of a thoracolumbosacral orthosis (TLSO) on gait performance in healthy adults during overground walking. Methods: Fourteen healthy volunteers walked with and without TLSO. Outcome measures consisted of spatiotemporal parameters and clinically important joint angular time profiles of the lower limbs. Joint angular time profiles were assessed in the sagittal, frontal and transversal plane. A paired t-test was used for discrete parameters and spm1d for assessing the joint angular time profiles. Results: Walking with a constraint resulted in decreased stride time and step time, increased step width and cadence. In the sagittal plane, no significant differences were observed regarding joint kinematics in the hip, knee and ankle. In the frontal plane, decreased adduction during stance and abduction during swing was observed in the hip. In the transversal plane, increased external rotation of the hip and increased internal rotation of the ankle was seen when wearing a contstraint. Conclusions: Wearing a TLSO can already bring forth significant changes in gait performance, suggesting an important relationship between trunk movements and mobility.

3

Differences in evaluation methods of trunk sway using different MoCap systems

Kutilek P., Socha V., Cakrt O., Svoboda Z.

Acta of Bioengineering and Biomechanics

|

2014

|

Vol. 16, no. 2

85--94

EN

The position of the trunk can be negatively influenced by many diseases. Several methods can be used for identifying defects in balance and coordination as a result of pathology of the musculoskeletal or nervous system. The aim of this article is to examine the relationship between the three methods used for analysis of trunk sway and compare two fundamentally different MoCap systems. We used a camera system and a 3DOF orientation tracker placed on subject’s trunk, and measured inclination (roll) and flexion (pitch) during quiet stance. Ten healthy participants in the study were measured with eyes open and closed. The pitch versus roll plots of trunk were formed, and the area of the convex hull, area of confidence ellipse and total length of the trajectory of the pitch versus roll plot were calculated. The statistical analysis was performed and strong correlation between the area of the convex hull and area of the confidence ellipse was found. Also, the results show moderate correlation between the area of the confidence ellipse and total length of the trace, and moderate correlation between the area of the convex hull and total length of the trace. In general, the different MoCap systems show different areas and lengths but lead to the same conclusions. Statistical analysis of the participants with eyes open and eye closed did not show significant difference in the areas and total lengths of the pitch versus roll plots.

4

Mechanical energy of the trunk during walking - does the model used influence the results?

Syczewska M.

Acta of Bioengineering and Biomechanics

|

2009

|

Vol. 11, nr 4

29-35

EN

The paper presents two trunk models. In the first one, the trunk is modelled as a series of seven segments, whose dimensions and inertial properties are parametrically based on body stature and body mass. In the second one, the trunk is modelled as one rigid segment. These models are used to calculate kinetic energy of the trunk relative movement with respect to the body centre of mass. The results show that in the case of healthy subject both models give similar results, but in the case of stroke subjects the simplified model leads to the underestimation of the energy amount and does not reflect all phases of gait when energy is generated.