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Numerical Analysis of Penetration Resistance Effects of Metal Matrix Composite Reinforcing in Spaced and Direct Configurations
David N. Lichlyter
Towards the pursuit of furthering the understanding of lightweight penetration resistant systems a study regarding metal matrix composite materials in penetration resistant configurations is considered. The metal matrix composite, MMC, studied is Al 6061/SiC and has a density very similar to homogeneous aluminum which is of interest when considering lightweight resistant systems. This effort seeks to by numerical analysis of experimentally validated models determine the effect of MMC inclusion in a system and additionally the effect of different configurations on the performance of the total system. This study focused on common reinforcement applications on aluminum base material targets. While the MMC reinforcement consistently displayed an improvement to the resistance of the system, there was not a significant difference in the resistance of the different configurations.
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Numerical Analysis of Taylor Impact with Various Nose Shapes
Jean C. Santiago Padilla and Erik M. Chappell
The Taylor impact test is an experimental technique used to determine dynamic material response and to validate constitutive models used in numerical simulations. It generally consists of shooting a cylinder rod of a select material against a rigid target at different velocities. After impact, the plastic deformation of the cylinder is recorded and is directly compared to numerical predictions. Another application for Taylor impact was proposed by Li et al. (2021) where the nose shape of the cylinder is modified to create different loading environments that can test electronic equipment in penetration weapons. FEA models where designed in ABAQUS/Explicit to recreate the force pulse shape and deformation of Taylor impact tests consisting of 3A21 Al rods with blunt, hemispherical, truncated ogive, and truncated conical nose shapes. A Johnson-Cook constitutive model was developed from available characterization tests, as well surrogate material data. Results showed good agreement in the deformation characteristics of the projectiles with experimental measurements, but failed to predict the distinct shock wave forms and peak loads during impact. Study exposed multiple limitations in the current FEA model to capture the loading environment in Taylor impact tests and suggests areas of improvement for future research.
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Numerical Analysis of Taylor Impact with Various Nose Shapes
Jean C. Santiago Padilla and Erik M. Chappell
The Taylor impact test is an experimental technique used to determine dynamic material response and to validate constitutive models used in numerical simulations. It generally consists of shooting a cylinder rod of a select material against a rigid target at different velocities. After impact, the plastic deformation of the cylinder is recorded and is directly compared to numerical predictions. Another application for Taylor impact was proposed by Li et al. (2021) where the nose shape of the cylinder is modified to create different loading environments that can test electronic equipment in penetration weapons. FEA models where designed in ABAQUS/Explicit to recreate the force pulse shape and deformation of Taylor impact tests consisting of 3A21 Al rods with blunt, hemispherical, truncated ogive, and truncated conical nose shapes. A Johnson-Cook constitutive model was developed from available characterization tests, as well surrogate material data. Results showed good agreement in the deformation characteristics of the projectiles with experimental measurements, but failed to predict the distinct shock wave forms and peak loads during impact. Study exposed multiple limitations in the current FEA model to capture the loading environment in Taylor impact tests and suggests areas of improvement for future research.
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Prediction of Residual Stresses in L-PBF Ti-6Al-4V Fatigue Specimens Using a Thermo-Mechanical Finite Element Model
Haley Petersen and Brad J. Sampson
Laser Powder Bed Fusion (L-PBF) is an additive manufacturing process that is becoming widely adopted in the automotive, aerospace, and biomedical industries. It uses a laser to melt metal in the form of powder to build parts in a layer-by-layer fashion based on an imported CAD geometry. The constant remelting of previous layers can produce unwanted thermally induced residual stresses in the part due to large thermal gradients, which can drastically reduce the fatigue life of the material. Predicting these residual stresses within the as-built part would be advantageous because one could better understand how the part will perform in an industrial setting. This study aims to use a combined thermo-mechanical finite element model to simulate the printing of fatigue specimens using L-PBF. The specimens are built based on Ti6Al4V material properties using a set of nominal process parameters. After the mechanical model of the specimen containing the induced residual stresses is created, the fatigue life of the part will be analyzed using constant amplitude stress-controlled loadings in FE-safe, and the results will be compared with that of a wrought Ti-6Al4V specimen.
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Prediction of Residual Stresses in L-PBF Ti-6Al-4V Fatigue Specimens Using a Thermo-Mechanical Finite Element Model
Haley Petersen and Brad J. Sampson
Laser Powder Bed Fusion (L-PBF) is an additive manufacturing process that is becoming widely adopted in the automotive, aerospace, and biomedical industries. It uses a laser to melt metal in the form of powder to build parts in a layer-by-layer fashion based on an imported CAD geometry. The constant remelting of previous layers can produce unwanted thermally induced residual stresses in the part due to large thermal gradients, which can drastically reduce the fatigue life of the material. Predicting these residual stresses within the as-built part would be advantageous because one could better understand how the part will perform in an industrial setting. This study aims to use a combined thermo-mechanical finite element model to simulate the printing of fatigue specimens using L-PBF. The specimens are built based on Ti6Al4V material properties using a set of nominal process parameters. After the mechanical model of the specimen containing the induced residual stresses is created, the fatigue life of the part will be analyzed using constant amplitude stress-controlled loadings in FE-safe, and the results will be compared with that of a wrought Ti-6Al4V specimen.
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Stress Concentrations in Sheave-trunnion Interference Fit Subjected to Bending
Jeffrey W. Hastings
An integral piece of all vertical lift bridges is the wire rope sheave assembly, which consists of a trunnion and sheave connected with an interference fit and set in roller bearings. An interference fit is a classic and reliable assembly method to connect a cylindrical shaft and hub by introducing a geometrical interference between their mating diameters. Many studies have been conducted on the stress concentrations found in the hub at the beginning of the connection, but the stress concentrations found in the shaft have not been thoroughly investigated. To improve the design of the trunnion-sheave assembly on vertical lift bridges, a study was performed on the stress concentrations found in the assembly using FEA software. This study focuses on the effect of the trunnion's mating diameter being overhung or inset with the hub, and design guidelines are provided.
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The Role of Blade Serrations in Stress Transformations During Cutting of Hard/ Soft Materials
Jonathan Paul Frady, Joshua David Singletary, Steven Boykin Brister, and Payne Aubrey Guilliams
The cutting ability of a blade is significantly impacted by the geometric characteristics of its serrations. This study will examine how titanium blades, with and without serrations, can cut into multiple types of materials. A total of five different blades and three different cutting block materials were used to examine the stresses, normal forces, and shear forces of the blade serrations. Analyzing the deformation of the cut material revealed how stresses caused by a serrated blade differ from those caused by non-serrated blades. The data from this examination was then used to determine the optimal geometry for serrations in blades.
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Trust Nonlinear Dynamic
Sami Zeggar and Adib El Mrabet Tarmach
The TRUST project's goal is to promote the efficient and responsive development of experimental, modeling, and simulation capabilities for future systems by constructing realistic testbeds that can be exercised more readily and efficiently. The testbeds will be used to conduct experiments in present and future engineering environments using complimentary modeling and simulation. TRUST required several tools in preproduction states and helped identify key features for future development. The required tools include: 1. Automated simulation management from the engineering common model framework (ECMF) 2. Version controlled model repositories for engineering analysis baseline models (EABM) 3. Experimental results databases (TIMS) 4. Communication and propagation of uncertainty (ECMF and TIMS) Future work will establish uncertainty propagation and explore additional and combined engineering environments. TRUST consists of three testbeds and the engineering analysis baseline models (EABMs) that go with them:
1. contact thermal conductivity (CTC)
2. nonlinear dynamics (ND)
3. sensors in environments (SE).
This project will focus on Nonlinear Dynamics (ND) testbed. Nonlinear material qualities can occasionally generate nonlinear behavior of a system under dynamic loading conditions. Many components of importance to the Weapons division at Los Alamos National Laboratory exhibit this behavior (LANL). The TRUST nonlinear dynamics testbed was created to investigate and improve on present dynamic modeling capabilities. Car crash, airplanes impact, bullets crossing metals, these materials deformed and their rate of strain changes in the material properties. That’s why it is a non-linear dynamic. Time is also a parameter in this and so does the non-linear material properties.
The goal of this research is to predict frequency of the linear response.
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Wing Design Utilizing Finite Element Analysis
Stephen D. Teasley and Amine Chaouki
The wings are some of the most important structures on an aircraft. They provide the lift necessary to get the plane airborne. The structure of the wing must be able to resist the forces acting on it: lift, thrust, drag, and weight. Therefore, the structural analysis of the wings is a vital part of airplane design. In this project, the finite element analysis software ABAQUS will be used to perform a structural analysis of a wing. The project deliverables for this project will include a 3D model of the wing and a structural analysis of the wing using the finite element method in order to determine factors including stress and deformation. Some other deliverables will include the safety factor of the wing and an optimum wing material. Based on its high safety factor and several other criteria such as cost and weight, the aluminum alloy AL 6061-T6 was selected as the optimum material.