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This PhD thesis presents an experimental investigation into the tensile properties, strengthening mechanics and failure mechanisms of three-dimensional (3D) woven composites with through-the-thickness (z-binder) reinforcement. 3D composites are being developed for the aerospace industry for structural applications in next-generation aircraft, such as wing panels, joints and stiffened components. The use of 3D woven composites in primary aircraft structures cannot occur until there has been a detailed assessment of their mechanical performance, including under tensile loading conditions. The aim of this PhD project is to provide new insights into the in-plane tensile properties, fatigue life, tensile delamination resistance and failure mechanisms of 3D woven composites with different amounts of z-binder reinforcement. Previous research has revealed that excessive amounts of z-binder reinforcement dramatically improves the tensile delamination toughness, but at the expense of the in-plane structural properties. For this reason, this PhD project aims to evaluate the tensile performance of 3D woven composites with relatively small z-binder contents (less than ~1%). The research aims to provide a better understanding of the manufacture, microstructure and tensile properties of 3D woven composites to assist the process of certification and application of these materials to aircraft structures as well as high performance marine and civil structures.

The implementation of technologies such as aluminum powder metallurgy (P/M) can be used in the automobile industry to have potential economic and environmental advantages. This technology to produce vehicle components can offer the combination of weight savings due to the low density of aluminum and material and machining savings via near net shape processing attributes. In an effort to expand the scope of application for aluminum P/M, considerable research has emphasized the development of new alloys and composites. One such alloy is P/M 2324, an aluminum-copper-magnesium alloy developed to have increased mechanical properties over the standard aluminum P/M alloys of the AC2014 type. The objective of this work was to undertake a comprehensive study on the effects of hot deformation on the emerging alloy P/M 2324 as well as the alloy with a SiC addition. Here, a forgeability study of these alloys and its wrought counterpart AA2024 was completed. To

Made available in DSpace on 2014-10-09T12:44:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:01Z (GMT). No. of bitstreams: 1 06998.pdf: 4836505 bytes, checksum: 8807c39ebe15873ea228aaf490e0ed91 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

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Made available in DSpace on 2014-10-09T12:44:45Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:01Z (GMT). No. of bitstreams: 1 06998.pdf: 4836505 bytes, checksum: 8807c39ebe15873ea228aaf490e0ed91 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Made available in DSpace on 2014-10-09T12:40:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:11Z (GMT). No. of bitstreams: 1 02951.pdf: 3722798 bytes, checksum: 4c42b3ba1eb1c51f8f47bb210f5763f4 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Histotripsy is a non-thermal, non-invasive, focused ultrasound ablation method that uses acoustic cavitation to mechanically break down tissues [1-8]. Histotripsy is heavily dependent on the mechanical properties of the tissue, allowing it to mechanically ablate tissues of lower mechanical stiffness while preserving the stiffer critical structures [15]. However, the mechanical properties of clinically relevant abdominal tissues and critical structures have not yet been adequately quantified under uniform testing parameters. Previous studies have tested and modeled the tissue selectivity of histotripsy, but these studies have been limited by the lack of mechanical property data available for these tissue types. In addition, there remains a need for additional experimental studies directly comparing the differential treatment doses required to induce histotripsy tissue damage in intra-abdominal tissue types. This thesis investigates the mechanical properties of intra-abdominal tissues under uniaxial tension, the effect of histotripsy treatment dose on intra-abdominal soft tissues and critical structures, and the potential of inducing damage to critical structures along the acoustic path pre-focal to the targeted histotripsy treatment. Results show that there are significant differences between the parenchymal tissues (liver, kidney) and the critical structure (stomach, gallbladder, small intestine, ducts, and vessels) elastic modulus, yield stress, yield strain, post-yield strain, energy to yield, and maximum stress and strain at yield. In general, histology analysis from the histotripsy experiments showed that there was an increase in tissue damage with increasing histotripsy pulses/point for all tissues. Critical structures with higher mechanical strength were more resistant to ablation compared to tissues with lower mechanical strength. Pre-focal studies showed damage to gallbladder and small intestine only in cases in which pre-focal cavitation was observed, while no damage occurred in skin and stomach for any samples treated at varying distances from the bubble cloud. Overall, this work improves our understanding of tissue selectivity of histotripsy and provides mechanical properties measurements for clinically relevant tissues that can be used to improve predictive models of tissue-selective histotripsy treatments. This work can be used in the planning of histotripsy treatments to establish proper margins of safety for treating intra-abdominal tumors. / Master of Science / Histotripsy is a non-invasive cancer treatment that mechanically breaks down tissues by rapidly forming and bursting bubbles within the tumor [1-8]. Histotripsy is heavily dependent on the mechanical properties of the tissue, allowing it to destroy weaker tissues while preserving the stiffer tissues in the surrounding area [15]. The mechanical properties of clinically relevant intra-abdominal tissues have not been quantified under uniform testing parameters. Previous studies have tested and modeled the tissue selectivity of histotripsy, but these studies have been limited by the mechanical property data available. This thesis investigates the mechanical properties of intra-abdominal tissues under tension, the effect of histotripsy treatment dose on intra-abdominal tissue damage, and the damage to critical structures from histotripsy treatment at varying distances from the tissue. Results show that there are significant differences between the liver and kidney mechanical stiffness and strength compared to the other tissues. In general, histology analysis showed that there is an increase in tissue damage with increasing histotripsy dose. Tissues with higher mechanical strength were more resistant to damage at lower doses compared to tissues with lower mechanical strength. Histotripsy damage to critical structures that are along the beam path, set distances in front of the focal point of the cavitation bubble cloud was studied. This study showed damage to gallbladder and small intestine only in cases in which pre-focal cavitation, cavitation bubbles that are not within the focal point of the cloud but are in contact with the tissue, was observed, while no damage occurred in skin and stomach for any samples treated at varying distances from the bubble cloud. Overall, this work improves our understanding of tissue selectivity of histotripsy and provides mechanical properties for clinically relevant tissues that can be used to improve predictive models of tissue-selective histotripsy treatments. This work can be used in the planning of histotripsy treatments to establish proper margins of safety for treating intra-abdominal tumors.

The study was performed at Billerudkorsnäs at the section Box Lab which offers knowledge and solutions for packaging. Paper that can be used to create packaging interacts with the surrounding environment, but has only been tested for a few climates. This thesis aims to investigate more climates and see how paper is affected by humidity and temperature and try to determine the cause of the results. The methods used to measure this was primary tensile test and moisture content analysis but also a test to evaluate creep was performed in climates with high humidity. From this, the mechanical properties of the paper were calculated. The test was performed in a climate chamber and the choice of methods was limited by what could be performed in the climate chamber. The materials tested were chosen to give a good representation of what is commonly used in the containerboard business. The climates for testing were selected from the ability of the climate chamber as well as interesting climates for the company. The results show that the papers are weakest at high RH, but the results indicate that the temperature solely impacts the properties of the paper. The highest moisture content does not necessarily mean the lowest value for a chosen property. The causes for the results are not clear since the patterns found are not bound to a certain quality but rather to paper in general. Therefore, more research on the area is suggested to try to determine what causes the material to react to temperature.

Hundreds of thousands of vascular bypass grafts are implanted in the United States every year, but there has yet to be an ideal graft material to substitute for one’s own autologous vessel. Many synthetic materials have been shown to be successful vessel replacements; however, none have been proven to exhibit the same mechanical properties as native vessels, one of the most important criteria in selecting a vascular graft material. Part of this issue is due to the fact that, currently, there is no “gold standard” for testing the longitudinal and transverse tensile properties of small diameter tubular materials. While there are ASTM and ISO standards that suggest ways to test tubes in their original form, many researchers have published tensile strength data based on cutting the tube and testing it as a flat sample. Thus, it was the aim of this thesis to understand, establish, and implement accurate tensile testing methods of small diameter polymers in their original, tubular state on Cal Poly’s campus. Two test fixtures were created based on specified design criteria in order to test materials in their tubular form in both the longitudinal and transverse directions. Both fixtures were successful in testing PLGA and ePTFE samples, and statistical data was gathered for the transverse test fixture. The new transverse test fixture was tested against the current method of testing, and a significant (α = 0.05) difference between methods was established for ultimate tensile strength. This analysis, however, cannot determine which test method is more accurate, thus more extensive testing is required to verify the design of both fixtures. By developing a method for testing small diameter polymers in tubular form on Cal Poly’s campus, it allows for more testing of various small diameter tubes and more comparative data to validate each design. It also demonstrates a need for a more detailed and widespread standardization of testing for small diameter tubes, especially in vascular substitute applications where the ideal vessel replacement has yet to be found.