There has been enormous boom in the air travel in recent times. There is increasing demand for the technological advancement nowadays towards the safety of the onboard passengers. Certification of aircrafts requires engineers to demonstrate that a head contact with any aircraft interior complies with the Head injury criteria (HIC) threshold of 1000 units specified in 14CFR 23.562, 25.562, 27.562. Analyzing injuries to the head of the occupant when it comes to contact with any aircraft cabin interiors is of serious issue. HIC compliance is a major concern for all the segments of the aircraft industry due to high cost involved in the certification. This research is an attempt to find a cost effective and yet valid approach to solve the HIC problem for the front row bulkhead seats in transport aircrafts. Previous experience, Quasi static testing, Finite element modeling and Madymo biodynamic simulations are utilized for the HIC compliant bulkheads. Madymo (Mathematical Dynamical Model) is a software package which can be used to simulate the dynamic behavior of Mechanical systems. It has a unique combination of fully integrated multibody and finite element techniques. Quasi static testing on various cell size honeycomb core configurations was carried out. Finite element modeling of honeycomb core was done using Msc Patran software package. Comprehensive parametric study has been carried out on different boundary conditions in which the bulkhead may be fixed. Variable thicknesses of the bulkhead which can be used has been looked upon in this study. Different restraint systems and varied seat setback distances have been used for the parametric study. Nylon belt and the Polyester belt are the two different types of belts with different elongation characteristics which are used in this study. The validated madymo models are then used to conduct a parametric study on the effect of the stiffness and strength of the bulkhead on HIC attenuation below the injury levels. / Thesis (M.S.)--Wichita State University, Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 66-69)

Potential applications of small rotorcraft unmanned aerial vehicles (UAVs) range from military missions to exploration of the planet Mars (Patrick C. O’Brien, 2003). Tasks such as exploration of unknown territories, formation flying, intelligence gathering etc, require UAV to be capable of flying very close to other flying or steady objects. Exposed rotary wings limit rotorcraft vehicle’s capability to fly in proximity of other objects. In some applications, such as rescue operation, urban warfare etc, it is highly desirable to cover exposed blades of rotorcraft UAV. This thesis work proposes a testbed for a mini rotorcraft UAV with protective shroud to demonstrate the capability of a rotorcraft to continue its flight after an impact with other object in environment, e.g. building wall. The quadrotor configuration is considered as a base vehicle for the testbed. A protective shroud for base vehicle is designed and built to protect rotors against the impact with wall. A closed loop attitude stability controller is developed and tested to ensure the stability of vehicle against high frequency vibrations from the rotors and disturbances from the impact. Experiments are carried out to prove the stability of the quadrotor vehicle after an impact with a building wall. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / Includes bibliographic references (leaves 57-59) / "May 2006."

Bipedal walking robots have distinguished themselves from other robots not only for their better mobility but also for the increased amount of complexity in their architecture. The issue of walking stability has inherently been related with these in various aspects from dynamics to controls. It has been defined in various ways for different aspects and these definitions have served as guidelines for designing a walking robot. This research is based on a design of a walking robot and development of a walking trajectory. Among the various approaches implemented in order to attain control of two-legged walking, this study attempted to linearize the walking trajectory by dividing it into finite discrete sections. Using the method of kinematics inversion to generate the initial open loop path, the study looks into implementation of the results for a successful walking mechanism. Further it dealt with stepping velocity control by using ground contact trigger and aimed at reducing the stress developed in joints due to dynamic forces. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 73-75).

The study of axial crush behavior of metal and composite tube has become a basis for the design of crashworthy structure in automotive and aircraft applications. Unlike metals, polymer composite material displays little or no plastic deformation characteristics. Research has showed that the hybrid tube usually made of inner aluminum tube over-wrapped with Eglass fiber reinforced epoxy have significantly higher energy absorption than either aluminum tube or composite tube. It is therefore important to have a predictive design tool that could simulate the response of the hybrid structure under impact or crush load. This thesis is aimed at the development and validation of finite element simulation methods for hybrid tubes. The axial crushing behavior and the energy absorption capacity of the aluminum-composite hybrid tube under quasi static and impact loading is studied using the LS-Dyna finite element solver. A square aluminum tube externally wrapped with E glass/epoxy composite layer at ±45° to tube axis is used for finite element analysis. A modified Chang-Chang failure model is used for the composite layers, exhibiting reasonable correlation with the experimental results. Simulations are carried out on composite and aluminum tubes separately. The results indicate that the energy absorption and crush behavior of the hybrid tubes are better than either the composite tubes or the aluminum tubes. In addition, analysis are also conducted on finite element tube to determine the effects of adhesion, ply orientation, and trigger geometry on load displacement response of hybrid tube. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 47-51)

Drilling is probably the most important conventional mechanical process and it is the most widely used machining operations. Prediction of cutting forces for any set of cutting parameters is essential in optimal design and manufacturing of products. It has been predicted that most of the problems associated with hole making operation, such as drilling, can be attributed to the force generated during cutting operation. In addition, prediction of force helps in design and evaluation of cutting tools and fixtures. The drilling of unidirectional carbon epoxy composite using conventional simple flute twist drill with/without the effect of chisel edge is analyzed. In this study, a series of drilling experiments are conducted on carbon fiber-reinforced composite laminates to determine quantitatively the effect of the chisel edge on the thrust force. In addition, tests are conducted to determine the effect of pre-drilling the laminate with a pilot hole. The results show a large reduction in the thrust force when a pilot hole is present which, in effect, removes the chisel edge contribution. An explicit finite element technique employing an Arbitrary Eulerian Lagrangian (ALE) is used in developing a finite element simulation of a 3Ddrilling process, one of the most complex material removal processes. In these simulations the work piece material and the air surrounding it are modeled using ALE elements. The generation of forces can be tracked using this tool. This objective of this thesis is finite element modeling of cutting forces and measuring the cutting forces generated during 3D-drilling process and comparing the forces with the experimental results. The results on the forces are found to be comparable between the FEA and experimental values. The work also discusses the challenges and methodology of using the LS-DYNA ALE capability for the drilling simulation. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 85-89)

The bleed air system in an aircraft engine is one of the most important systems for flight operation and is the heart of the aircraft engine pneumatic system. It consists of ducts and components that supply high pressure bleed air from the engine compressor to the other systems. The functioning of bleed air system plays a vital role in flight safety, ground operations, and coordination with other existing systems [1] including fuel system, lubrication system, ignition system, and anti-ice system. A prior Wichita State University Research and Creative Award (URCA) research project entitled "Aircraft Pneumatic Leak Detection Methods" was the motivation for this thesis work. In this research, different inspection techniques were studied to detect leaks in bleed air ducts. Existing conditions such as continuous high pressure and temperature loading within a duct can make it prone to leak because of high stress concentration areas, pre-existing flaws, or manufacturing defects. A general-purpose finite element package, ABAQUS was used for stress analysis of cracked structures such as tubular T-joints. The high stress concentration region at the intersection of the duct joints was assumed to have certain initial flaws. This initial crack flaw was analyzed using line-spring elements to compute the stress intensity factor (SIF). The values of SIF obtained from the present analysis were compared with appropriate results in the literature. Stresses from the finite element analysis were used as input in AFGROW, a crack growth software package consisting of extensive material properties and all necessary fracture mechanics parameters required for crack-growth analysis. Damage tolerance was applied to estimate the life of the duct. The leak-before-break concept was used to determine whether crack growth in the duct would lead to any kind of leak or catastrophic failure. Crack and leak detection techniques to evaluate the crack size are discussed. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 71-75)

Hydroforming of aluminum sheets is very important in the aircraft industry, due to the advantages of less wrinkling and cost effectiveness. Numerous research has been conducted in this field, which deals with the development of methods and tools to control accuracy of the bend and prediction of the springback after the sheet metal has been formed. Rivets are the most commonly used fasteners to fit together the subassemblies of the aircraft. The holes for riveting are punched after any forming operation due to the tensile and compressive deformations along the thickness of the sheet metal, which can affect the dimension and position accuracy of the hole. This incurs more cost and time due to the development of special dies for accurately punched holes. It is necessary to develop a method for predicting variation in the holes, which will increase the cost effectiveness of the process. In this research, sheet metal with pre-drilled holes was evaluated for a bending operation using a hydroforming technique. Sheet metal with a variety of thicknesses, bending radii, and bending angles was evaluated. Variation in the dimensional tolerance was attained using the minimum radial separation method. A dataset of dimensional variation in the holes was developed and used for development of the artificial neural network, which was able to predict the dimensional variation of the hole if an unknown pattern of inputs was provided. This study presents the prediction of the dimensional variation of holes due to sheet metal bending using the hydroforming technique. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006." / Includes bibliographic references (leaves 74-78)

As is passenger safety of paramount importance to the manufacturer of passenger vehicles, so is the security of the nation to its government. Recent developments in the usage of heavy vehicles by militant outfits to carry out attack has become the main concern of many governments around the world, hence the existence of some kind of barrier to stop heavy vehicles from entering restricted areas was thought of. This barrier must be able to provide both visibility and security without being much expensive. Existence of a concrete wall will undoubtedly provide security but at the same time visibility of the impending danger to the security personnel is compromised. A wall is usually rigid and costs a lot to repair, alter and replace. More over a wall can serve only the purpose stated above; it cannot be used as dead ends to stop vehicles. Also concrete walls occupy more space and are difficult to transport from place to place. A bollard pole with sufficient energy absorbing capability can be used, both, for the above stated reasons as well as a simple restraint at dead ends of a road to save lives. These are more versatile for the reason that they can be used as stationary or be motorized to serve the purpose. Also these provide pedestrians and cyclists through passage as well as restrict large vehicle from passing through. Three dimensional models of the bollard poles with various cross-sections are made and a study is done using Finite Element softwares such as LS-Dyna 970 to find the maximum energy the bollards can absorb and still be able to function normally. The bollards are made from two different materials and a study is made to see whether the material of the bollard is reason for bollard failure at high impact speeds. / Thesis (M.S.)--Wichita State University, Dept. of Mechanical Engineering. / "May 2006."

The purpose of this research is to examine the gender pay-gap and the potential factors that contribute to income inequality. Since passing the Equal Pay Act the median weekly earnings of women is still just $0.72 for every dollar men earn. To put this in context the pay-gap in 1970 was $0.62 and in 1992 it was $0.75 (Institute for Women’s Policy Research, 1993). Secondary data analysis of the 2003 American Time Use Survey purports the potential reasons why the pay-gap still continues. This research employs an alternative income determination model with three component parts: the individual-level segment, which includes variables such as education and age; the structural-level segment, which includes variables such as hours worked per week, industry, and occupation; a gender-level segment, which includes variables such as sex, marital status, and with child under age six. Results indicate that, net of other factors, women earn $111.21 less per week than men in spite of having a higher percentage of college degrees and positions in white-collar high-skill employment. Analysis of the results suggests that there are two potential means by which the pay-gap can be reduced. Women are typically, either by choice or because they are forced, selected into gender homogenous positions such as education or healthcare that are devalued. Women therefore need to select positions that will generate a more heterogeneous employment structure and pursue occupations in typically male dominated areas. Additionally, the enactment of a Pay Equity Act could further restore the balance and redistribute income by evaluating positions based on the value of their work and not based on sex, race, or other personal/individual attributes. / Thesis (M.A.)--Wichita State University, Dept. of Sociology. / "May 2006."

This study investigated the effects of explicit teaching of morphemic analysis on vocabulary learning and comprehension and its transfer effects to novel words with sixth grade students. Because research states that vocabulary and the ability to decode unfamiliar words is vital for comprehension, an increase in vocabulary learning and comprehension was predicted. A sixth-grade reading class with low reading assessment results was specifically taught twelve affixes and roots chosen from a bank of morphemes tested in classroom theme and state reading assessments. The 18 students received pre and post assessments on comprehension and vocabulary with an additional post assessment on transfer effects. Results showed significantly higher post-assessment scores, but no visible improvement on student transfer to novel. / Thesis (M.Ed.)--Wichita State University, College of Education, Dept. of Curriculum and Instruction / "May 2006."