Engineering Commons^™

In Mold Flow Of Long Fibers In Compression Molding Process, Gleb Meirson

Electronic Thesis and Dissertation Repository

Long Fiber Thermoplastics (LFT) are promising new materials with high physical properties and low density. These high properties are obtained by embedding very long fibers (~100 mm) into a thermoplastic matrix. Such a high fiber length dictates the use of a compression molding process for manufacturing as the length of discontinuous fibers in injection molding is limited by pellet length.

LFT composites are of great interest for the automotive industry. These materials are already used in some interior and exterior car parts such as bumpers, seat structures, door module etc. This research is inspired by the desire to manufacture load …

Fem Analysis Of Composite Stringers For An Airplane Fuselage, Akashsingh Birendrasingh Thakur

Mechanical and Aerospace Engineering Theses

With the advent of technology, materials have advanced many folds; One such technical revelation has been Fiber-reinforced Composite Materials. Composite materials have two major advantages, among many others: Improved strength and stiffness, especially compared to other materials on a unit weight basis. For example, Composite materials have stiffness comparable to the stiffness of steel but with a strength decimal order higher and more than three times lighter. These advantages have led to new aircraft and spacecraft designs that are radical departures from past efforts based on conventional materials. The stringers serve to take up(along with the skin) the compression and …

Finite Element Modeling And Stress Distribution Of Unidirectional Composite Materials Under Transversal Loading, Pavan Agarwal

Mechanical and Aerospace Engineering Theses

Micromechanics of Composites analyze stresses inside any heterogeneous material. These stresses can not only be used for calculation of effective stiffness or compliance, but also for predicting strength and failure modes for these materials. This thesis is devoted to the stress analysis of unidirectional composites by finite element method. The key distinction from other finite element method modeling of the unidirectional composite was that the load on the cell was not prescribed, but was to be calculated taking into account the influence of the closest neighbors of the cell. Transversal unidirectional tension/compression and transversally symmetrical biaxial tension/compression were analyzed. In …

Mechanical Properties And Fatigue Behavior Of Unitized Composite Airframe Structures At Elevated Temperature, Mohamed Noomen

Theses and Dissertations

The tension-tension fatigue behavior of a newly developed unitized composite material system was investigated. The unitized composite consisted of a polymer matrix composite (PMC) co-cured with a ceramic matrix composite (CMC). The PMC portion consisted of an NRPE high-temperature polyimide matrix reinforced with carbon fibers woven in an eight harness satin weave (8HSW). The CMC layer is a single-ply non-crimp 3D orthogonal weave composite consisting of ceramic matrix reinforced with glass fibers. In order to assess the performance and suitability of this composite for use in aerospace components designed to contain high-temperature environments, mechanical tests were performed under temperature conditions …

Finite Element Based Cross-Sectional Buckling Optimization For A Constant Area, Pinned-Pinned Composite Column, Anirudh Srinivas

Mechanical and Aerospace Engineering Theses

In archery, dynamic buckling compromises the target accuracy of arrows. For both dynamic and quasi-static buckling, the buckling load depends on the cross-sectional area moment of inertia, which can be increased by modifying the cross-sectional shape of the arrow shaft. Arrows commercially available today are made up of composite materials and have a tubular circular cross-section. In this study an effort has been made to optimize the cross-sectional shape of the composite arrow shaft, using finite element based, quasi-static buckling analysis keeping the length and area of the cross-section constant. The composite column is pinned at both ends and is …

Torsional Behaviour And Finite Element Analysis Of The Hybrid Laminated Composite Shafts: Comparison Of Vartm With Vacuum Bagging Manufacturing Method, Mehmet Emin Taşdelen, Mehmet Halidun Keleştemur, Ercan Şevkat

Faculty Publications - Mechanical Engineering

Braided sleeve composite shafts are produced and their torsional behavior is investigated. The braided sleeves are slid over an Al tube to create very strong and rigid tubular form shafts and they are in the form of 2/2 twill biaxial fiber fabric that has been woven into a continuous sleeve. Carbon and glass fibers braided sleeves are used for the fabrication of the composite shafts. VARTM (vacuum assisted resin transfer molding) and Vacuum Bagging are the two different types of manufacturing methods used in the study. Torsional behaviors of the shafts are investigated experimentally in terms of fabrication methods and …

Processing Of Al-12si-Tnm Composites By Selective Laser Melting And Evaluation Of Compressive And Wear Properties, Konda Prashanth, Sergio Scudino, Anil Chaubey, Lukas Löber, Pei Wang, Hooyar Attar, Frank Schimansky, Florian Pyczak, Jürgen Eckert

Research outputs 2014 to 2021

Al-12Si (80 vol%)-Ti52.4Al42.2Nb4.4Mo0.9B0.06 (at.%) (TNM) composites were successfully produced by the selective laser melting (SLM). Detailed structural and microstructural analysis shows the formation of the Al6MoTi intermetallic phase due to the reaction of the TNM reinforcement with the Al-12Si matrix during SLM. Compression tests reveal that the composites exhibit significantly improved properties (∼140 and ∼160 MPa higher yield and ultimate compressive strengths, respectively) compared with the Al-12Si matrix. However, the samples break at ∼6% total strain under compression, thus showing a reduced plasticity of the composites. Sliding wear tests were carried out for both the Al-12Si matrix and the Al-12Si-TNM …