Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS≥4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005). Crash conditions were investigated through use of a modified side sled model used to reproduce the key conditions present in full scale crash tests. The model accounts for several important factors that contribute to occupant response based on the literature. These factors are; the relative velocities between the seat and door, the occupant to door distance, the door shape and compliance. The side sled model was validated by reproducing the crash conditions present in FMVSS 214 and IIHS side impact tests and comparing the thoracic compression, velocity, and Viscous Criterion (VC) response determined by the model to the response of the ES-2 dummy used in the crash tests. Injury was predicted by evaluating VCmax, selected for its ability to predict rate-sensitive soft tissue injury during thoracic compression (Lau & Viano, 1986). The Ford Taurus FMVSS 214 and Nissan Maxima IIHS tests were selected from side impact crash test data found in the NHTSA database because they included factors not present in standard side impact test procedures. These factors were; the presence of door accelerometers used to provide input velocities to the side impact model and the use of a ES-2 (rather than the SID) to facilitate comparison of VC response to the human body model. Also, the two crash test procedures (FMVSS 214 & IIHS) were selected to ensure accurate side impact model response to different impact scenarios. The side impact model was shown to closely reproduce the timing and injury response of the full-scale FMVSS 214 side impact test of a Ford Taurus, as well as the IIHS side impact test of a Nissan Maxima. The side impact model was then used to investigate the effects of door to occupant spacing, door velocity profile, armrest height, seat foam, restraint system, and arm position. It was found that the VCmax was controlled by both the first and second peaks typically found in door velocity profiles, but the effect of each varies depending on the situation. This study found that VCmax was reduced by 73-88% when door intrusion was eliminated compared to the VC response incurred by an intruding door. Also, the presence of a deformable door based on physical geometry and material characteristics rather than a simplified rigid door reduced VCmax by 16% in this study. The study on seat foam determined that significant effects on VC response can be made by modest adjustments in foam properties. Low stiffness seat foam was found to increase VCmax by 41% when compared to the VC response when using high stiffness foam. Arm position has been proven to be a relevant factor in side impact crash. Positioning the arms parallel to the thorax, in the “down” position, caused a 42% increase in VCmax when compared to the VC response determined with the arms positioned at 45 degrees. Finally, although restraint systems have limited influence on side impact crash safety compared to front and rear impacts, this study found that the presence of a pre-tensioning restraint system reduced VCmax by 13% when compared to the VC response of an un-belted occupant. It should be noted that the current study was limited to velocity profiles obtained from a specific FMVSS 214 test and therefore results and observations are restricted to the confines of the input conditions used. However, the side impact model developed is a useful tool for evaluating factors influencing side impact and can be used to determine occupant response in any side impact crash scenario when the appropriate input conditions are provided.

Thoracic injury is the most dominant segment of automotive side impact traumas. A numerical model that can predict such injuries in crash simulation is essential to the process of designing a safer motor vehicle. The focus of this study was to develop a numerical model to predict lung response and injury in side impact car crash scenarios. A biofidelic human body model was further developed. The geometry, material properties and boundary condition of the organs and soft tissues within the thorax were improved with the intent to ensure stress transmission continuity and model accuracy. The thoracic region of the human body model was revalidated against three pendulum and two sled impact scenarios at different velocities. Other body regions such as the shoulder, abdomen, and pelvis were revalidated. The latest model demonstrated improvements in every response category relative to the previous version of the human body model. The development of the lung model involved advancements in the material properties, and boundary conditions. An analytical approach was presented to correct the lung properties to the in-situ condition. Several injury metric predictor candidates of pulmonary contusion were investigated and compared based on the validated pendulum and sled impact scenarios. The results of this study confirmed the importance of stress wave focusing, reflection, and concentration within the lungs. The bulk modulus of the lung had considerable influence on injury metric outcomes. Despite the viscous criterion yielded similar response for different loading conditions, this study demonstrated that the level of contusion volume varied with the size of the impact surface area. In conclusion, the human body model could be used for the analysis of thoracic response in automotive impact scenarios. The overall model is capable of predicting thoracic response and lung contusion. Future development on the heart and aorta can expand the model capacity to investigate all vital organ injury mechanisms.

Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS≥4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005). Crash conditions were investigated through use of a modified side sled model used to reproduce the key conditions present in full scale crash tests. The model accounts for several important factors that contribute to occupant response based on the literature. These factors are; the relative velocities between the seat and door, the occupant to door distance, the door shape and compliance. The side sled model was validated by reproducing the crash conditions present in FMVSS 214 and IIHS side impact tests and comparing the thoracic compression, velocity, and Viscous Criterion (VC) response determined by the model to the response of the ES-2 dummy used in the crash tests. Injury was predicted by evaluating VCmax, selected for its ability to predict rate-sensitive soft tissue injury during thoracic compression (Lau & Viano, 1986). The Ford Taurus FMVSS 214 and Nissan Maxima IIHS tests were selected from side impact crash test data found in the NHTSA database because they included factors not present in standard side impact test procedures. These factors were; the presence of door accelerometers used to provide input velocities to the side impact model and the use of a ES-2 (rather than the SID) to facilitate comparison of VC response to the human body model. Also, the two crash test procedures (FMVSS 214 & IIHS) were selected to ensure accurate side impact model response to different impact scenarios. The side impact model was shown to closely reproduce the timing and injury response of the full-scale FMVSS 214 side impact test of a Ford Taurus, as well as the IIHS side impact test of a Nissan Maxima. The side impact model was then used to investigate the effects of door to occupant spacing, door velocity profile, armrest height, seat foam, restraint system, and arm position. It was found that the VCmax was controlled by both the first and second peaks typically found in door velocity profiles, but the effect of each varies depending on the situation. This study found that VCmax was reduced by 73-88% when door intrusion was eliminated compared to the VC response incurred by an intruding door. Also, the presence of a deformable door based on physical geometry and material characteristics rather than a simplified rigid door reduced VCmax by 16% in this study. The study on seat foam determined that significant effects on VC response can be made by modest adjustments in foam properties. Low stiffness seat foam was found to increase VCmax by 41% when compared to the VC response when using high stiffness foam. Arm position has been proven to be a relevant factor in side impact crash. Positioning the arms parallel to the thorax, in the “down” position, caused a 42% increase in VCmax when compared to the VC response determined with the arms positioned at 45 degrees. Finally, although restraint systems have limited influence on side impact crash safety compared to front and rear impacts, this study found that the presence of a pre-tensioning restraint system reduced VCmax by 13% when compared to the VC response of an un-belted occupant. It should be noted that the current study was limited to velocity profiles obtained from a specific FMVSS 214 test and therefore results and observations are restricted to the confines of the input conditions used. However, the side impact model developed is a useful tool for evaluating factors influencing side impact and can be used to determine occupant response in any side impact crash scenario when the appropriate input conditions are provided.

Thoracic injury is the most dominant segment of automotive side impact traumas. A numerical model that can predict such injuries in crash simulation is essential to the process of designing a safer motor vehicle. The focus of this study was to develop a numerical model to predict lung response and injury in side impact car crash scenarios. A biofidelic human body model was further developed. The geometry, material properties and boundary condition of the organs and soft tissues within the thorax were improved with the intent to ensure stress transmission continuity and model accuracy. The thoracic region of the human body model was revalidated against three pendulum and two sled impact scenarios at different velocities. Other body regions such as the shoulder, abdomen, and pelvis were revalidated. The latest model demonstrated improvements in every response category relative to the previous version of the human body model. The development of the lung model involved advancements in the material properties, and boundary conditions. An analytical approach was presented to correct the lung properties to the in-situ condition. Several injury metric predictor candidates of pulmonary contusion were investigated and compared based on the validated pendulum and sled impact scenarios. The results of this study confirmed the importance of stress wave focusing, reflection, and concentration within the lungs. The bulk modulus of the lung had considerable influence on injury metric outcomes. Despite the viscous criterion yielded similar response for different loading conditions, this study demonstrated that the level of contusion volume varied with the size of the impact surface area. In conclusion, the human body model could be used for the analysis of thoracic response in automotive impact scenarios. The overall model is capable of predicting thoracic response and lung contusion. Future development on the heart and aorta can expand the model capacity to investigate all vital organ injury mechanisms.

The aim of this study is to present a design approach for compliant bistable four-link mechanisms. The design constraints are the two positions of the mechanism, the force required to snap between the positions and the fatigue life of the designed mechanism. The theory presented here will be applied to the door lock mechanism used in commercial dishwashers, which is originally designed as a rigid inverted slider crank mechanism snapping between two positions with the force applied by a spring. The mechanism is re-designed as a compliant bistable four-link mechanism and a prototype has been manufactured.

This dissertation presents new concepts and methodology in designing shape-morphing structures using bistable elements. Developed using the Pseudo-Rigid-Body Model (PRBM), linear bistable compliant mechanism elements produce predictable and controllable length changes. Step-by-step design procedures are developed to guide the design process of these bistable elements. Two different examples of Shape-Morphing Space Frames (SMSFs) were designed and prototyped utilizing the bistable linear elements in a single-layer grid, in addition to flexures and rigid links, to morph a cylindrical space frame into both a hyperbolic and a spherical space frame. Moreover, bistable unit-cell compliant-mechanism elements were also developed to morph a compact structure from a specific initial shape to a final specific shape. The detailed design of those unit cells were done using Computer-aided design (CAD) software following a novel design procedure to transform a one-degree-of-freedom mechanism into a structure with sufficient compliance within its links to toggle between two chosen stable positions. Two different design examples were investigated in this research and prototyped to demonstrate the ability to morph disks into a hemisphere or a sphere with the structure being stable in both states (disk and sphere).

<p>Many opportunities for frequent transit between the lunar vicinity and the heliocentric region will arise in the near future, including servicing missions to space telescopes and proposed missions to various asteroids and other destinations in the solar system. The overarching goal of this investigation is the development a framework for periodic and transit options in the Earth-Moon-Sun system. Rather than overlapping different dynamical models to capture the dynamics of the cislunar and heliocentric region, this analysis leverages a four-body dynamical model, the Bicircular Restricted Four-Body Problem (BCR4BP), that includes the dynamical structures that exist due to the combined influences of the Earth, the Moon, and the Sun. The BCR4BP is an intermediate step in fidelity between the CR3BP and the higher-fidelity ephemeris model. The results demonstrate that dynamical structures from the Earth-Moon-Sun BCR4BP provide valuable information on the flow between cislunar and heliocentric spaces. </p> <p><br></p> <p>Dynamical structures associated with periodic and bounded motion within the BCR4BP are successfully employed to construct transfers between the 9:2 NRHO and locations of interest in heliocentric space. The framework developed in this analysis is effective for transit between any cislunar orbit and the Sun-Earth libration point regions; a current important use case for this capability involves departures from the NRHOs, orbits that possess complex dynamics and near-stable properties. Leveraging this methodology, one-way trajectories from the lunar vicinity to a destination orbit in heliocentric space are constructed, as well as round-trip trajectories that returns to the NRHO after completion of the objectives in heliocentric space. The challenges of such trajectory design include the phasing of the trajectory with respect to the Earth, the Moon, the Sun, on both the outbound and inbound legs of the trajectory. Applications for this trajectory include servicing missions to a space telescope in heliocentric space, where the initial and final locations of the mission is the Gateway near the Moon. Lastly, the results of this analysis demonstrate that the properties and geometry of the periodic orbits, bounded motion, and transfers that are delivered from the BCR4BP are maintained when the trajectories are transitioned to the higher-fidelity ephemeris model. </p>

In this master thesis it have been investigated how the stiffness of a seat affect the risk of neck injuries, e.g whiplash associated disorders, in a rear end low velocity car collision using a female human body model, HBM, and if dividing the seat into several sections with different stiffnesses. The project is performed in collaboration with CEVT, China Euro Vehicle Technology, a innovation center of the Geely Holding Group. The HBM used is the VIVA open source HBM developed by Chalmers University of Technology together with Volvo Cars, The Swedish National Road and Transport ResearchInstitute (VTI) and Folksams forskningsstiftelse. Two different seats were investigated, a generic seat and the seat of the existing Lynk&amp;Co 01. The stiffness of the seat had a significant impact on the risk of neck injuries, but does not seem to be a good idea to divide the seat into several sections since the height of the individual in the seat influence what stiffness is optimal for each section. It was also discovered that the relative distance between the head and the headrest at the moment of impact has a great affect on the risk of neck injuries.

The purpose of this research is to present a class of Self-Retracting Fully-compliant Bistable Micromechanisms (SRFBM). Fully-compliant mechanisms are needed to overcome the inherent limitations of microfabricated pin joints, especially in bistable mechanisms. The elimination of the clearances associated with pin joints will allow more efficient bistable mechanisms with smaller travel. Small travel, in a linear path facilitates integration with efficient on-chip actuators. Tensural pivots are developed and used to deal with the compressive loading to which the mechanism is subject. SRFBM are modeled using the Pseudo-Rigid-Body Model and finite element analysis. Suitable configurations of the SRFBM concept have been identified and fabricated using the MUMPs process. Complete systems, including external actuators and electrical contacts are 1140 μm by 625 μm (individual SRFBM are less than 300 μm by 300 μm). These systems have been tested, demonstrating on-chip actuation of bistable mechanisms. Power requirements for these systems are approximately 150 mW. Testing with manual force testers has also been completed and correlates well with finite element modeling. Actuation force is approximately 500 μN for forward actuation. Return actuation can be achieved either by external actuators or by thermal self-retraction of the mechanism. Thermal self-retraction is more efficient, but can result in damage to the mechanism. Fatigue testing has been completed on a single device, subjecting it to approximately 2 million duty cycles without failure. Based on the SRFBM concept a number of improvements and adaptations are presented, including systems with further power and displacement reductions and a G-switch for LIGA fabrication.

Haptic interfaces are robotic force-feedback devices that give the user a sense of touch as they interact with virtual or remote environments. These interfaces act as input devices, mapping the 3-dimensional (3D) motions of the user's hand into 3D motions in a slave system or simulated virtual world. A major challenge in haptic interfaces is ensuring that the user's experience is a realistic depiction of the simulated environment. This requires the interface's design to be such that it does not hinder the user's ability to feel the forces present in the environment. This "transparency" is achieved by minimizing the device's physical properties (e.g., weight, inertia, friction). The primary objective of the work is to utilize compliant mechanisms as a means to improve transparency of a haptic interface. This thesis presents work toward the design of a fully compliant mechanism that can be utilized in haptic interfaces as a means to reduce parasitic forces. The approach taken in this work is to design a series of mechanisms that when combined act as a statically balanced compliant joint (SBCJ). Simulated and experimental results show that the methods presented here result in a joint that displays a significant decrease in return-to-home behavior typically observed in compliant mechanisms. This reduction in the torque needed to displace the joint and the absence of friction suggest that the joint design is conducive to the methods previously proposed for increasing transparency in haptic interfaces.