1. Introduction and Overview. 2. Detecting Influential Observations and Outliers. 3. Detecting and Assessing Collinearity. 4. Applications and Remedies. 5. Research Issues and Directions for Extensions. Bibliography. Author Index. Subject Index.

Regression Diagnostics: Identifying Influential Data and Sources of Collinearity

Abbreviated Injury Scale

We show that the nonlinear mechanical response of networks formed from un–cross-linked fibrin or collagen type I continually changes in response to repeated large-strain loading. We demonstrate that this dynamic evolution of the mechanical response arises from a shift of a characteristic nonlinear stress–strain relationship to higher strains. Therefore, the imposed loading does not weaken the underlying matrices but instead delays the occurrence of the strain stiffening. Using confocal microscopy, we present direct evidence that this behavior results from persistent lengthening of individual fibers caused by an interplay between fiber stretching and fiber buckling when the networks are repeatedly strained. Moreover, we show that covalent cross-linking of fibrin or collagen inhibits the shift of the nonlinear material response, suggesting that the molecular origin of individual fiber lengthening may be slip of monomers within the fibers. Thus, a fibrous architecture in combination with constituents that exhibit internal plasticity creates a material whose mechanical response adapts to external loading conditions. This design principle may be useful to engineer novel materials with this capability.

https://www.pnas.org/content/pnas/110/30/12197.full.pdf

Strain history dependence of the nonlinear stress response of fibrin and collagen networks

Anterior cruciate ligament reconstruction is a frequently performed orthopaedic procedure. Although short-term results are generally good, long-term outcomes are less favorable. Thus, there is renewed interest in improving surgical techniques. Recent studies of anterior cruciate ligament anatomy and function have characterized the 2-bundle structure of the native ligament. During non-weightbearing conditions, the anteromedial (AM) and posterolateral (PL) bundles display reciprocal tension patterns. However, during weightbearing, both the AM and PL bundles are maximally elongated at low flexion angles and shorten significantly with increasing knee flexion. Conventional single-bundle reconstruction techniques often result in nonanatomic tunnel placement, with a tibial PL to a femoral “high AM” tunnel position. In vitro studies have demonstrated that these nonanatomic single-bundle reconstructions cannot completely restore normal anterior-posterior or rotatory laxity. Cadaveric studies suggest that anatomic ...

Anatomic Single- and Double-Bundle Anterior Cruciate Ligament Reconstruction, Part 1: Basic Science

The objective of this study was to develop full body CAD geometry of a seated 50th percentile male. Model development was based on medical image data acquired for this study, in conjunction with extensive data from the open literature. An individual (height, 174.9 cm, weight, 78.6 ± 0.77 kg, and age 26 years) was enrolled in the study for a period of 4 months. 72 scans across three imaging modalities (CT, MRI, and upright MRI) were collected. The whole-body dataset contains 15,622 images. Over 300 individual components representing human anatomy were generated through segmentation. While the enrolled individual served as a template, segmented data were verified against, or augmented with, data from over 75 literature sources on the average morphology of the human body. Non-Uniform Rational B-Spline (NURBS) surfaces with tangential (G1) continuity were constructed over all the segmented data. The sagittally symmetric model consists of 418 individual components representing bones, muscles, organs, blood vessels, ligaments, tendons, cartilaginous structures, and skin. Length, surface area, and volumes of components germane to crash injury prediction are presented. The total volume (75.7 × 103 cm(3)) and surface area (1.86 × 102 cm(2)) of the model closely agree with the literature data. The geometry is intended for subsequent use in nonlinear dynamics solvers, and serves as the foundation of a global effort to develop the next-generation computational human body model for injury prediction and prevention.

Development of a full body CAD dataset for computational modeling: a multi-modality approach

Overview of a combined computational-experimental evaluation for the assessment of panoramic sunroof impact characteristics for ejection mitigation.

The goal of this study was to assess the behaviour of an obese Human Body Model (HBM) in frontal sled tests. The results of rear-seat sled tests with an obese (BMI = 35) Post Mortem Human Surrogate (PMHS) were used to evaluate the performance of the obese HBM in matching conditions. Also, the responses of a non-obese HBM (BMI = 25) and the obese HBM were compared in a front-seat frontal impact test. In the rear-seat tests, both the obese HBM and the obese PMHS experienced a large forward excursion, delayed lap belt engagement with the pelvis, and a reclined-to-upright torso angle throughout the tests, which were the effects of large body mass and thick flesh. In the front-seat simulations, the obese HBM experienced a larger excursion than the non-obese HBM. The obese HBM can be a useful tool to design and optimise restraint system for front-seat occupants with obesity.

Evaluation of behaviour of an obese human body model in frontal sled tests

Obesity is associated with higher fatality risk and altered distribution of occupant injuries in automotive collisions partially because of the increased depth of abdominal soft tissue, which results in limited or delayed engagement of the lap belt with the pelvis and increases the risk of pelvis submarining under the lap belt exposing occupant abdomen to belt loading. Previous modeling studies have shown that pelvis submarining could not be replicated using existing human body models. The goal of this study is to perform model modifications and investigate whether they could lead to model submarining. By detaching the connections between the pelvis and surrounding flesh, submarining like belt kinematics were observed. By remeshing the flesh parts of the model, similar belt kinematics was observed but the pelvic wings were fractured. Finally, large shear deformation on the flesh together with submarining like kinematics were observed in the model with its flesh modeled using the meshless Smooth Particle Galerkin Method SPG method. The results of this study showed that SPG method has potential to simulate large deformations in soft tissue which may be necessary to improve the biofidelity of belt/pelvis interaction.

New approaches in modeling belt-flesh-pelvis interaction using obese GHBMC models

Sensitivity of scale factor choice on injury response for equal-stress equal-velocity scaling.

The World Bank estimates that between 41% and 75% of all road traffic fatalities worldwide are pedestrians and that nearly 35% of all pedestrian fatalities are children. Three factors are important to fully understand a vehicle pedestrian collision. The environment, the vehicle and the pedestrian contribute to accidents and determine their outcome. Further, the accident can be divided into three parts on a time-scale; pre-, in- and post-crash. In each of these time events, the environment, vehicle and road user are more or less influential factors important to consider. Our aim in this chapter is to describe the fundaments of vehicle-pedestrian collisions, covering aspects like influencing factors of the collision, the vehicle structures responsible for pedestrian injuries and active- passive countermeasures from the injury biomechanics point of view.


Keywords:

pedestrian;
traffic;
injury;
vehicle;
accident

Jason R. Kerrigan

Papers

Overview of a combined computational-experimental evaluation for the assessment of panoramic sunroof impact characteristics for ejection mitigation.

Evaluation of behaviour of an obese human body model in frontal sled tests

New approaches in modeling belt-flesh-pelvis interaction using obese GHBMC models

Sensitivity of scale factor choice on injury response for equal-stress equal-velocity scaling.

Pedestrian Protection Overview