Biomedical subjects

Jong B Lee

Publications and source records attributed to Jong B Lee.

6 recordsLinked to original sources

PubMed2006

Effect of assumed stiffness and mass density on the impact response of the human chest using a three-dimensional FE model of the human body.

The mass density, Young's modulus (E), tangent modulus (Et), and yield stress (sigma y) of the human ribs, sternum, internal organs, and muscles play important roles when determining impact responses of the chest associated with pendulum impact. A series of parametric studies was conducted using a commercially available three-dimensional finite element (FE) model, Total HUman Model for Safety (THUMS) of the whole human body, to determine the effect of changing these material properties on the predicted impact force, chest deflection, and the number of rib fractures and fractured ribs. Results from this parametric study indicate that the initial chest apparent stiffness was mainly influenced by the stiffness and mass density of the superficial muscles covering the torso. The number of rib fractures and fractured ribs was primarily determined by the stiffness of the ribcage. Similarly, the stiffness of the ribcage and internal organs contributed to the maximum chest deflection in frontal impact, while the maximum chest deflection for lateral impact was mainly affected by the stiffness of the ribcage. Additionally, the total mass of the whole chest had a moderately effect on the number of rib fractures.

Computer Simulation↗

PubMed2005

Numerical Investigations of Interactions between the Knee-Thigh-Hip Complex with Vehicle Interior Structures.

Although biomechanical studies on the knee-thigh-hip (KTH) complex have been extensive, interactions between the KTH and various vehicular interior design parameters in frontal automotive crashes for newer models have not been reported in the open literature to the best of our knowledge. A 3D finite element (FE) model of a 50(th) percentile male KTH complex, which includes explicit representations of the iliac wing, acetabulum, pubic rami, sacrum, articular cartilage, femoral head, femoral neck, femoral condyles, patella, and patella tendon, has been developed to simulate injuries such as fracture of the patella, femoral neck, acetabulum, and pubic rami of the KTH complex. Model results compared favorably against regional component test data including a three-point bending test of the femur, axial loading of the isolated knee-patella, axial loading of the KTH complex, axial loading of the femoral head, and lateral loading of the isolated pelvis. The model was further integrated into a Wayne State University upper torso model and validated against data obtained from whole body sled tests. The model was validated against these experimental data over a range of impact speeds, impactor masses and boundary conditions. Using Design Of Experiment (DOE) methods based on Taguchi's approach and the developed FE model of the whole body, including the KTH complex, eight vehicular interior design parameters, namely the load limiter force, seat belt elongation, pretensioner inlet amount, knee-knee bolster distance, knee bolster angle, knee bolster stiffness, toe board angle and impact speed, each with either two or three design levels, were simulated to predict their respective effects on the potential of KTH injury in frontal impacts. Simulation results proposed best design levels for vehicular interior design parameters to reduce the injury potential of the KTH complex due to frontal automotive crashes. This study is limited by the fact that prediction of bony fracture was based on an element elimination method available in the LS-DYNA code. No validation study was conducted to determine if this method is suitable when simulating fractures of biological tissues. More work is still needed to further validate the FE model of the KTH complex to increase its reliability in the assessment of various impact loading conditions associated with vehicular crash scenarios.

Journal Article↗

PubMed2005

Development of a Three-Dimensional Finite Element Chest Model for the 5(th) Percentile Female.

Several three-dimensional (3D) finite element (FE) models of the human body have been developed to elucidate injury mechanisms due to automotive crashes. However, these models are mainly focused on 50(th) percentile male. As a first step towards a better understanding of injury biomechanics in the small female, a 3D FE model of a 5(th) percentile female human chest (FEM-5F) has been developed and validated against experimental data obtained from two sets of frontal impact, one set of lateral impact, two sets of oblique impact and a series of ballistic impacts. Two previous FE models, a small female Total HUman Model for Safety (THUMS-AF05) occupant version 1.0Beta (Kimpara et al. 2002) and the Wayne State University Human Thoracic Model (WSUHTM, Wang 1995 and Shah et al. 2001) were integrated and modified for this model development. The model incorporated not only geometrical gender differences, such as location of the internal organs and structure of the bony skeleton, but also the biomechanical differences of the ribs due to gender. It includes a detailed description of the sternum, ribs, costal cartilage, thoracic spine, skin, superficial muscles, intercostal muscles, heart, lung, diaphragm, major blood vessels and simplified abdominal internal organs and has been validated against a series of six cadaveric experiments on the small female reported by Nahum et al. (1970), Kroell et al. (1974), Viano (1989), Talantikite et al. (1998) and Wilhelm (2003). Results predicted by the model were well-matched to these experimental data for a range of impact speeds and impactor masses. More research is needed in order to increase the accuracy of predicting rib fractures so that the mechanisms responsible for small female injury can be more clearly defined.

Journal Article↗

PubMed2005

Injury patterns and sources of non-ejected occupants in trip-over crashes: a survey of NASS-CDS database from 1997 to 2002.

The objective of this study was to investigate the main injury patterns and sources of non-ejected occupants (i.e. no full/partial ejection) during trip-over crashes, using the NASS-CDS database. Specific injury types and sources of the head, chest, and neck were identified. Results from this study suggest that cerebrum injuries, especially subarachnoid hemorrhage, rib fractures, lung injuries, and cervical spine fractures need to be emphasized if cadaveric tests or numerical simulations are designed to study rollover injury mechanisms. The roof has been identified as the major source for head and neck injuries. However, changing the roof design alone is not likely to improve rollover safety. Instead, the belt restraint systems, passive airbags, roof structure, and new innovations need to be considered in a systematic manner to provide enhanced rollover occupant protection.

Accidents, Traffic↗

PubMed2002

Mechanical characterization of porcine abdominal organs.

Typical automotive related abdominal injuries occur due to contact with the rim of the steering wheel, seatbelt and armrest, however, the rate is less than in other body regions. When solid abdominal organs, such as the liver, kidneys and spleen are involved, the injury severity tends to be higher. Although sled and pendulum impact tests have been conducted using cadavers and animals, the mechanical properties and the tissue level injury tolerance of abdominal solid organs are not well characterized. These data are needed in the development of computer models, the improvement of current anthropometric test devices and the enhancement of our understanding of abdominal injury mechanisms. In this study, a series of experimental tests on solid abdominal organs was conducted using porcine liver, kidney and spleen specimens. Additionally, the injury tolerance of the solid organs was deduced from the experimental data.

Journal Article↗

PubMed2002

Three layer impact simulation for large cranioplasty using non-linear finite element model.

In this study, we conducted biomechanical study about implant material and behavior of large cranioplasty upon post-operative impact injury. Previous studies utilized a surface model of the skull and large cranium patch (defect area is 46.7 cm2)[1,2,3,4]. It had single layer with thickness of adult skull as 7 cm in the parietal bone. After construction of the finite element model, the mesh and node data were analyzed for the static behavior of the patch. Four-node and three-node quadrilateral shell elements were mainly used in this model to adapt easily to complex shapes. The overall model consists of 4,740 nodes, 2,168 solid elements, and 4,736 shell elements. Even though, the elements could demonstrate the displacement, stress, and strain by longitudinal along the force direction, subsequent result could not reveal the dynamic behavior of the model. Normal adult skull is consisting of three layers (inner, outer and diploë layer). This structure resembles composite materials that behave differently upon impact. In order to overcome limitation of previous model, we designed physiological model and analyzed dynamic behavior with new implant materials. The composite implant with two popular materials and middle polymer layer was evaluated and compared with bony material.

Biomechanical Phenomena↗