NUST Institutions Library Catalogue Search for 'an:"126485"'

Energy Absorption of Hybrid Lattice Structure based crash box designed for Additive manufacturing /

By Khan ,Mehmood. . 77p. ; 30cm..

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Additive Manufacturing and Damping Characterization of Wave Springs: Numerical and Experimental Approach /

By Khan, Basit . . 121p. , Additive manufacturing (AM) enables the production of complex geometries that are challenging to achieve with traditional manufacturing methods. Wave springs, developed using AM, offer superior load-bearing capacity, lightweight structure, high energy absorption efficiency, and enhanced stiffness compared to conventional helical springs, making them ideal for advanced engineering applications. This research examines the dynamic behavior of AM-fabricated wave springs, with a focus on their potential for vibration isolation and energy absorption. Employing a combination of finite element analysis (FEA) and experimental testing, the study evaluates the effects of geometric variations on the damping characteristics and natural frequencies of the wave springs. The findings reveal how AM enables the creation of wave springs with customized dynamic properties, offering advantages in optimizing performance for specific applications and functional requirements. The results indicate that the rectangular wave spring design exhibited a damping ratio approximately 38% higher than the round design and 12% greater than the variable thickness design. Additionally, the study examines the fatigue resistance of AM-fabricated wave springs for all designs, assessing their durability under repeated loading conditions. It further revealed a trade-off between resonance frequency and durability, with the rectangular design achieving the highest fatigue life. By demonstrating the potential of AM to produce wave springs with tailored dynamic properties, this research contributes to sustainable industrial innovation. 30cm.

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Design of Additive Manufactured Hybrid Lattice Structures for Enhanced Mechanical Performance /

By Sher, Muhammad Gul . . 77p. , By enabling the manufacture of sophisticated lattice structures with tailored mechanical qualities, additive manufacturing has changed the fabrication of complex geometries. This work offers a hybrid lattice design meant to enhance mechanical performance and energy absorption by combining bending-dominated face-centered cubic (FCC) cells with stretch-dominated Iso Truss cells. Systematically created were nine separate hybrid lattice configurations made up of linked face-centered cubic (IFCC) and hybrid designs marked HS1 through HS5. Selected for its biodegradability and beneficial mechanical qualities, polylactic acid (PLA) was employed to construct the structures utilizing the fused deposition modeling (FDM) technique. Essential for correct performance assessment, the manufacturing technique was honed to ensure accuracy and structural integrity. Mechanical behavior and energy absorption characteristics of the suggested lattice architectures were evaluated using finite element models. Under quasi-static compression loads, the simulations produced knowledge on stress distribution, deformation patterns, and expected failure mechanisms. Quasi-static compression tests were done to confirm the modeling findings and explore the real deformation processes. The experimental setting followed defined testing techniques to assure the reliability and repeatability of the findings. The results suggested that the unique hybrid lattice structure (IFCC) displayed increased mechanical performance compared to homogeneous FCC and ISO truss structures, notably in load-bearing capacity, stiffness, and specific energy absorption (SEA). The inclusion of a layered staking hybrid lattice architecture boosted mechanical performance and transformed the deformation process to a more controlled layer-by-layer failure mode. The IFCC hybrid lattice acquired a specific energy absorption (SEA) of 3.93 kJ/kg. Among the layered hybrid topologies, HS4 displayed the greatest SEA of 5.96 kJ/kg, representing increases of 332% and 555% compared to homogeneous FCC and ISO truss structures, respectively. The results emphasize the potential of hybrid lattice structures to produce customized mechanical characteristics in energy-absorbing applications, aiding future improvements in lightweight, high-performance materials. shown that some hybrid arrangements, notably HS4 and HS5, exhibited increased energy absorption and structural integrity compared to alternative designs. The arrangements displayed a synergistic impact by successfully combining the positive features of both bending-dominated and stretch-dominated cells. In contrast, designs like HS3 and IFCC demonstrated modest energy dissipation, typified by varied deformation behaviors that indicated a poor balance between stiffness and energy absorption. The study underlines the need of combining varied lattice geometry to get specific mechanical characteristics. Utilizing the geometric and material flexibility of additive printing allows the construction of lattice structures suited for specific uses. This research gives substantial insights for the production of lightweight, high-performance materials useful in energy-absorbing situations, such as protective equipment, automobile components, and aircraft frameworks.

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Prediction and Improvement of warpage in parts fabricated using material extrusion process /

By Sufyan, Muhammad . . 80p. , Additive Manufacturing (AM) has transformed manufacturing by enabling the fabrication of complicated geometries with less material waste which is particularly beneficial in a variety of industries, including aerospace, automotive, healthcare, and consumer goods. Fused Deposition Modeling (FDM) is a prominent approach in the realm of AM, attributed to its economic practicality, user-friendly execution, and material flexibility. The persistent of warpage in FDM poses a critical challenge in FDM affecting dimensional accuracy, fitment and mechanical reliability of components. Despite advancements, a lack of comprehensive studies on the combined effects of key process parameters limits the ability to predict and mitigate the effect of warpage. This research aims at providing approaches to rectify warpage in FDM-printed parts a priority based on process improvements. This research investigates three critical printing parameters i.e., raster pattern, bed temperature, and infill density. Samples are printed with various printing conditions and warpage is measured followed by validation using FEA analysis. The initially developed predictive model gained relatively high precision with overall variance of value being less than 10% in accordance with experimental tests. FEA simulations show that the FCC raster pattern decreases warping by 40% than the grid raster pattern. Similarly, 80ºC bed temperature decreases warpage by 30% comparing with 40ºC. Infill density of 90% decreases warpage by 20% more than 10% infill density. Optimizing key process parameters in FDM can significantly reduce warpage, improving dimensional accuracy and mechanical reliability in precision-critical applications. 30cm.

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Investigation of Impact Properties of Wave Springs Designed for Additive Manufacturing /

By Ahmed, Faizan . . 119p. , Innovation continues to transform various fields, including the design of springs. Initially helical springs were used as compression springs for most of the applications. However, the design innovation has led to the introduction of a new type of compression spring which is the wave spring. At the same time the advancements in manufacturing technologies are reshaping the production methods. Traditional manufacturing methods are gradually being replaced with additive manufacturing. Because AM has the ability to fabricate complex geometries with high precision and minimal material waste. These advantages make AM a key driver of innovation in modern design and engineering. Wave springs possess better mechanical properties as compared to helical springs, as highlighted by previous studies. But previous studies are limited to only compression analysis of wave springs at slow speeds. The behavior of this newly developed spring is unknown for sudden high speed impact loadings. This research involves the experimental and computational analysis of six different geometries of wave spring under the high speed loading conditions of 17mm/sec. The six geometries of wave springs are fabricated using FDM technology. PLA material was considered for the fabrication due to its availability and compatibility with the FDM. The other 2 materials including spring steel, and TPU (Thermoplastic Polyurethane) were used in computational modelling only. The results mainly showed that the material properties had a greater influence over the geometric parameters. PLA due to its brittle nature resulted in formation of local stresses that minimized the performance parameters of all geometries of wave springs. Spring steel having high elasticity and compressive strength showed better impact properties unlike PLA. TPU although elastic but moderate compressive strength was not able to show impact properties like spring steel, but due to its elasticity, it was a better choice over PLA. Each of the 6 geometries had different configurations that resulted in different local stress formations and thus different energy absorption, stiffness, and load-bearing capacity. To apply the concept of wave spring to real-engineering world, multiple wave spring designs were integrated in the car suspension system and analyzed on MSC Adams (Automated Dynamic Analysis of Mechanical Systems) for their energy absorption, stiffness, and maximum load bearing capacity. This analysis further validated the initial results and provided a gateway to the innovation in the car suspension system design and analysis. 30cm.

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3D Printing of Nickel Based Super Alloy for Aero-Engine Applications /

By Absar, Muhammad . . 118p. , From the past few years, Additive Manufacturing (AM) or 3D printing has achieved a significant role among the latest emerging technologies of the fourth industrial revolution. 3D printing strategy allows us to build components of various materials without any geometrical constraint. This feature is unique in the field of industrial production, and it has transformed the traditional manufacturing concept of mechanical design permitting lightweight components and improving stiffness. Moreover, another advantage of additive manufacturing is decreased production waste and energy consumption. The Nickel based Super Alloy powder has its wide applicability in the defense industry and mainly Aero-Engine components. This can also be used for biomedical, power generation and automotive applications. Nickel and its alloys are useful due to their properties at elevated temperatures. The aim of this research was to develop the build parameters of Nickel based powder and successfully print functional parts using Selective Laser Melting (SLM) process. The properties desired for the functional part have been verified through mechanical testing. The print worthiness of this powder along with desired results achieved through this research has led to qualified printing of metal parts for high temperature applications. In the presented thesis, the objective was to conduct a series of experiments to develop parameters for printing Nickel based superalloy K465 powder for aero-engine applications. The properties that were evaluated against the printing parameters include Actual Density measurement, Microstructure and Tensile values. The best samples were optically viewed to look for microstructure. Alongside metallography, UTS samples were printed to carry xv out mechanical testing of the best samples. The experiment yielding finest results was chosen for functional part printing. Though additive manufacturing of nickel-based superalloys presents significant technological advancement, their unique material behavior and properties also present several common challenges like fusion of layers, microstructure control, residual stress and cracking during 3D printing that require careful consideration and process optimization. The K465 superalloy powder is also prone to cracking which was faced during this research. Though higher preheat temperatures were provided to mitigate this issue, cracking couldn’t be avoided due to available SLM limitation. To avoid this challenge, the further optimization of developed K465 parameters can be carried out through EBM process and even through more R&D and advanced strategies at SLM machine discussed in this thesis. These studies will be crucial for optimizing K465 additive manufacturing processes and ensuring the production of crackfree, high-integrity components for the most demanding applications. 30cm.

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