Engineering Commons^™

Interlaminar Tensile Properties Of Unidirectional And Woven Carbon Fiber Reinforced Toughened Epoxy Laminates, Eric Timothy Casey, Sean Mckalip Thompson

Materials Engineering

This project aims to develop a dataset on interlaminar tensile strength comparing unidirectional and woven thermoset matrix carbon fiber composites keeping ply count, matrix material, and fiber diameter constant. The interlaminar tensile strength is an important property relating to the delamination failure mode. Interlaminar tensile strength is determined using the ASTM D6415 testing standard. This test is a modified four-point bend test using a 90° curved beam test specimen. Laminates were produced by laying up pre-impregnated carbon fiber sheets onto a curved beam tooling. The unidirectional laminate was produced with 20 plies in a [0,0,90,0,0]₄ layup pattern. The woven …

Investigation Of The Effects Of Cladding Layers On Longitudinal And Transverse Mechanical Properties In Composite Laminates, Rachel Potratz, Tiffany Foo, Joseph Kamlet

Materials Engineering

The addition of cladding layers to composite laminates is used in industry to improve bond adhesion and the ease of manufacturing. However, there is no public data on the effects of cladding layers on the mechanical properties of composite components. To directly observe how cladding layers affect mechanical properties, four laminates with zero, one, two, and three cladding layers of twill fabric were added symmetrically to a biased core. The mechanical testing performed was tensile, short beam strength, and compression testing in the longitudinal and transverse directions. The measured strengths were related to the longitudinal properties of the core, and …

Evaluating The Effects Of Granulated Rubber And Glass Fibers In Polymer Concrete As A Structural Material For Wafer Grinding Machines, Kevin Gabriel Kuehn, Philip Randall Streeter

Materials Engineering

Polymer concrete is a composite material used to replace cast iron and steel in wafer grinding machines for vibration damping. During the grinding and lapping processes of manufacturing silicon wafers, excessive vibrations may cause subsurface damage which requires additional polishing and reduces yield. Nine compositions containing various levels of granulated rubber and glass fibers were manufactured. CRM WRF-10 granulated rubber was examined at 0%, 5%, and 10% and Corning Cem-Fil glass fibers were added at 0%, 0.5%, and 1% by weight. Smooth-On EpoxAcast 690 epoxy resin was held constant at 16% for each composition. Crushed granite aggregate from Martin Marietta, …

Strengthening Of 7175 Aluminum Alloy Through Multi-Step Aging Process, Colin E. Masterson, Ryland W. Jolliffe

Materials Engineering

7175 is a heat-treatable aluminum alloy commonly used in aerospace forgings. This alloy is aged with a multi-step heat treatment. This treatment must balance strength with stress corrosion cracking resistance through a degree of overaging. The team was tasked by Weber Metals to increase the strength of this treatment without sacrificing stress corrosion cracking resistance. Both two-step and retrogression and reaging treatments were tested in experiments to find a heat treatment that could increase the yield and tensile strength by 1-2 ksi while maintaining a minimum electrochemical conductivity equivalence of 38% relative to copper. Two-step aging is the more conventional …

Modifying Casting Parameters To Improve The High Temperature Ductility Of Investment Cast Nickel-Based Superalloy Pwa 1455, Lars Alexander Hedin, Cole Magnum Introligator

Materials Engineering

PCC Structurals, an industry leader in superalloy investment castings, has observed inconsistencies in the stress rupture performance of polycrystalline nickel-based superalloy PWA 1455. PCC has changed their casting parameters to reduce the thermal gradient during cooling but have been unable to correlate these changes with an increase in stress rupture elongation. Metallographic examination of past samples indicated microstructures composed of non- equiaxed dendritic grains with mean diameter of .021 inches along the test axis. A similar study on polycrystalline superalloys has indicated that excessive superheat temperatures above the liquidus can result in large grains identical to those observed, limiting the …

Development Of Low Cost, Environmentally Friendly And High Strength Carbon Foams From Bread And Cake, Laura Mountain-Tuller

Materials Engineering

Carbon foam is a high niche material that consists of a highly porous, three-dimensional cellular network that is characterized by extremely high strength-to-weight ratios and low thermal conductivity. Due to these properties, carbon foams excel in structural and thermal applications, especially in the aerospace industry. Typically, carbon foams are formed through a heating process called pyrolysis of polymer precursors with high carbon content. This process is done at high temperatures in an oxygen free environment. These precursors are expensive to make and use toxic chemicals to produce, therefore, there is a push to find an environmentally friendly and cost-effective method …

The Effects Of Varying Composition And Build Direction On Direct Metal Deposition Fabricated Inconel 718, Abigail P. Nilan, Jessica M. Fordham

Materials Engineering

Inconel 718 (IN718) is a popular wrought superalloy, and is currently being investigated for additive manufacturing (AM) applications in the aerospace industry. However, overaging and the presence of microcracks have caused a significant reduction in properties. The purpose of this study is to meet or exceed the mechanical properties of wrought IN718 by varying the composition and build direction of the AM alloy. Alternative compositions were selected with Oerlilon Metco’s Rapid Alloy Development (RAD) software, and differ in niobium content, which increases the fraction of the primary strengthening phase (γʺ). Direct metal deposition (DMD) was used to fabricate the samples, …

Development Of Test Methods For Measuring Fiber Misalignment And Warping In Honeycomb-Core Composite Panels, Wyatt Taylor, Haripriya Nilakantan

Materials Engineering

Zodiac Aerospace manufactures honeycomb-core composite panels to be used in aircraft cabin interior components. During the manufacturing process, some panels become warped such that they cannot be used for their designated aircraft cabin components. As a result, these panels are scrapped because they cannot be recycled. About 44 to 90% of panels become warped during manufacturing. Warping is caused by many factors, including layer misalignment, processing parameters such as temperature and pressure gradients, and fiber misalignment in the prepregs. Currently, Zodiac does not have any data on the effect of fiber misalignment on panel warpage, so a testing protocol was …

Anomalous 304 Stainless Steel Mechanical Properties In Medical Guide Wires, Andrew Joseph Freeman

Materials Engineering

Stainless steel medical guide wire cores, processed by Abbott Vascular, are returning anomalous mechanical properties upon strain hardening and heat treatment. As theory dictates, mechanical strength properties increase with strain hardening, and decrease with an annealing treatment. The opposite response is being observed. This is counter intuitive to fundamental materials knowledge, and a perfect materials engineering paradox. This project was designed to characterize these behaviors, and attempt to determine causation. To accomplish this, tensile testing of all processing steps mapped the mechanical property evolution of the wire. Published literature research revealed the potential of nitrogen and chromium solid state diffusion …

Characterization Of Slm Printed 316l Stainless Steel And Investigation Of Microlattice Geometry, Finley H. Marbury

Materials Engineering

The goal of this project was firstly to characterize Cal Poly’s SLM printed 316L stainless steel. SEM analysis showed Cal Poly’s as-printed 316L material to have a cellular dendritic microstructure containing mostly austenite and a small amount of δ-ferrite. After being heat treated to eliminate warp, its yeild and ultimate tensile strength were on par with the literature, however higher modulus and lower elongation were observed. XRD analysis confirmed residual stresses in the material, and that grains are preferentially oriented in both heat treated and non heat treated samples. The amount of porosity in the material was found to be …

Invariant-Based Method For Improving Efficiency Of Mechanical Testing In Aerospace Certification Of Carbon Fiber-Epoxy Composites, Alyssa Rina Gruezo, Erika Gabrielle Hansen

Materials Engineering

The current challenge with qualification of carbon fiber composites in the aerospace industry would be the low efficiency of testing hundreds of samples. The Trace Theory strives to streamline the qualification process by utilizing a material’s Trace to predict properties of composites using Excel programs and basis data. To test this theory, predicted properties from the program, QuickLam, were compared to experimental data. Unidirectional 0° (T1), unidirectional 90° (T2), quasi-isotropic (T3), and hard quasi-isotropic (T4) laminates were made using HexTowR carbon fiber and TC250 resin provided by TenCate Advanced Composites. Tensile and compression tests were done according to ASTM D3039 …

Development Of Low Cost Braze Alloys For Aerospace Applications, Alyssa M. Elliott, Sandy Babich, Blake Whitmee

Materials Engineering

Non-precious metal braze alloys can help lower the cost of brazing, which is a commonly-used joining process in the aerospace industry. A-286, a stainless steel superalloy, and Inconel© 718, a nickel-based superalloy, are both commonly used alloys at Aerojet Rocketdyne. Both alloys were brazed into butt joints using nickel-based braze alloys: AMS 4776, 4777, and 4778. The brazed samples were machined into a modified version of the ASTM E8 subsize specimen samples and tensile tested to compare the strength and calculated elongation of the brazed samples to the base metals’ properties. All of the brazed samples fractured at the joint, …

Predicting Flexural Strength Of Composite Honeycomb Core Sandwich Panels Using Mechanical Models Of Face Sheet Compressive Strength, Nicholas Bruffey, William Shiu

Materials Engineering

The design process at Zodiac Aerospace requires the ability to accurately predict the strength of a composite honeycomb core sandwich panel to adhere to strict FAA regulations. The most common failure mode in long beam composites is in compression. Following ASTM D7249 for a four-point bend test of a long beam flexural test, a mechanical model has been developed that relates the compressive strength of glass fiber face sheets to the flexural strength of the sandwich panel. Zodiac does not currently have data on the compressive strength of the face sheets, so testing was performed to find this property. Asymmetric …

Buckling Strength In Carbon Fiber Polymer Matrix Composites Produced By Filament Winding For Structural Use In Rockets, Kyle Rosenow

Materials Engineering

High-powered rockets use thin walled carbon-fiber reinforced polymer (CFRP) tubes as the primary structure and the tubes experience compressive stress during flight, which is estimated at 18MPa. Cal Poly Space Systems (CPSS) recently acquired the capability to use filament winding for manufacturing CFRP structures. Filament winding wraps carbon-fiber tow coated in epoxy around an axisymmetric object, and in this case, an aluminum cylinder. The tube laminate is an angle-ply orientation testing the winding angles 35°, 50°, 65°, and 80° and winding patterns 1/1 and 8/1 in combination using an unsupported parallel compression test. Coupons are one-inch in height, 2.5 inches …

Solution Casting And Mechanical Testing Of Arabinan-Cellulose Nanocomposites, Kevin Su, Alina Lusebrink

Materials Engineering

The purpose of this work was to investigate methods to produce consistent, reliable, and testable thin films of arabinan-cellulose nanocomposites. Mechanical properties and composition of the Opuntia ficus-indica cactus spines served as motivation for this research. The high specific strength and stiffness, biodegradability, and sustainability of these spines inspired the creation of composites fabricated from the same materials found in cactus spines: arabinan and nanocrystalline cellulose (NCC). Arabinan serves as the matrix material and NCC as the reinforcement. To explore the feasibility of using a non-toxic solvent, different solution casting techniques with water as a solvent were investigated. Ultrasonication was …

Improving Product Design By Predicting Flexural Strength Of A Honeycomb Core Sandwich Panel Composite Using Ply Tensile Strength, Justin Lui, Javal Patel

Materials Engineering

The use of composite sandwich panels has increased in the aerospace industry. Prediction of a theoretical composite construction's flexural properties is important for efficient composite product designs. Utilizing the four point flexure geometry defined by Zodiac Aerospace, Santa Maria, CA, a mechanical model was derived to predict the flexural behavior of a theoretical honeycomb core sandwich composite using laminate tensile properties. The most common failure mode of Zodiac Aerospace’s four point bend test is a failure in tension of the bottom laminate. Given this information, ASTM D3039 (Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials) was chosen …

Investigating The Cause Of Unique Mechanical Behavior In Platinum Alloy Guidewire Tips, Evan Borgeson, Alfred Rosen

Materials Engineering

The platinum alloy used by Abbott Vascular in guidewire tips exhibits a yielding behavior characterized by an abrupt transition from elastic to plastic zones and high ductility. This yielding behavior was hypothesized to be a result of one of three structural phenomena: ordering, solute strain aging, or interstitial strain aging. To test for these strengthening mechanisms in the wire, X-ray diffraction analysis, heat treatments, and tensile testing were completed. The wire has a diameter of 0.0025 inches and was supplied in two forms, the final stress relieved state, and as-drawn from the production line. Heat treatments were performed at 130 …

Analysis Of Compression Creep Deformation Of 7050 Aluminum Large Scale Open Die Forgings During The Solution Heat Treatment Process, Ashley Lopez, Elysha Cole

Materials Engineering

A stress, ranging from 104.17 to 166.67 psi, was applied to 0.5 in diameter cylindrical samples of 7050 aluminum using a manufactured fixture that applies stress using an indenter with a diameter of 0.127 in. The stress range used replicates the stresses produced on large scale forgings weighing up to 4000 lbs. We chose a maximum, medium and low stress as our stress parameters. The samples were placed into the fixture for stability then placed in a furnace heated to 890°F which is the solution heat treatment temperature for 7050 aluminum. The heat treatment times varied between 4 and 24 …

High Cycle Rotating Bending Fatigue Of 6061-T6 Friction Stir Welded Extrusions, John Chang, Travis Miller

Materials Engineering

Fatigue testing was done on friction stir welded joints of 6061-T6 aluminum extrusions. Tests were run using a rotating bending fatigue machine at stresses from 111.5 to 138.7 MPa. Failures occurred on the order of 10⁵ to 10⁷ cycles, and an S-N curve was generated based off of the failure results. After the samples failed, the location of the failure and the number of cycles to failure were noted. Fatigue samples were designed in SolidWorks with a tapered 2 inch reduced section. The 2 inch reduced section will include the entire weld region as seen from the microhardness …

Low Velocity Impact Tower Feasibility, Setup, And Impact Testing Of Carbon Fiber Reinforced Epoxy Thermoset And Peek Thermoplastic Matrix Composites, Brent Plehn

Materials Engineering

A low velocity impact tower was donated to Cal Poly's Materials Engineering Department along with four fiber reinforced polymer matrix composites. The tower was set up in building 192 in the Mechanical Testing Laboratory. Improvements were made to the tower including adding velocity detection capabilities, making loose hardware inclusive, adding an extra tower arm for better consistency, adding a double jawed clamp for faster testing, and rerouting the tower's compressed air system to improve performance. A standard operating procedure was drafted, tested, and redrafted for impact testing composite panels. The four composite panels consisted of two quasi-isotropic 16 ply AS-1 …

Simplifying The Testing And Calculation Of Fracture Toughness Of Thermoplastic And Thermoset Matrix Composite Materials, James Shedden

Materials Engineering

Fracture toughness, or the ability of a material to resist fast fracture by crack propagation is an important property in the use of composite materials for structural designs. Other mechanical tests such as tensile, flexure, and compression are more established and practical than testing fracture toughness. Fracture toughness testing is less commonly used because it requires specific specimens and non-conventional test methods. In composite materials specifically, delamination of the plies of materials is tested for G_IC and G_IIC values to find the critical strain energy release rate of the two types of fracture modes. The common two tests …

Discontinuous Grain Boundaries Of Forged René 41, Steven Crump

Materials Engineering

Forged components must pass a grain size specification (grain size, distribution) for acceptance in an application. The varying amounts of plastic deformation during forging can lead to abnormally large recrystallized grain sizes in certain regions of the part, which will not pass specification. The question exists whether these abnormally coarse grains are truly comprised of poly crystalline fine grains with grain boundaries resistant to etching techniques. To investigate this abnormal grain size effect, a cross section of a forged René 41 nickel-based superalloy aircraft engine ring was cut and sectioned into six segments. Those segments were then prepared for microstructural …

Biaxial & Twist Testing Of Composite Carbon-Fiber Sandwich Panels For Automotive Racing Vehicles, Erik Eckberg

Materials Engineering

Composite sandwich panels were constructed with 4-ply plain weave carbon-fiber/epoxy face sheets in the 0^o/45^o/0^o/45^o orientation and 1/8^th inch Nomex honeycomb core. The panels were cut into 5-inch square test plates for mechanical testing. All testing was done on a fixture designed and fabricated by Pratt & Miller Engineering and installed on an Instron testing system at Cal Poly. The twist test was performed by supporting diagonal corners of the plate while simultaneously loading the opposite two corners at a crosshead rate of .06 in/min (ASTM 3044-94R11). Out of 10 panels tested, …

Effects Of Alternate Cementitious Materials On Compressive Strength And Environmental Impacts Of Cement Mix Designs., Mitchell R. Bush

Materials Engineering

Specific proportions of Portland cement, fly ash, and blast furnace slag cement mixtures where chosen by a ternary phase diagram to be investigated. By experimental testing and company data history fly ash was limited to not exceed 30% and contribution of Portland cement must be over 50%. Ten chosen mix designs were batched by following ASTM C305-94 and cured for twenty-eight and forty-two days, the extended cure length allows the reaction of pozzolanic material with calcium hydroxide to complete. Compressive strength testing at forty-two days yielded low strength for mix designs with 20% or less Portland cement compared to our …

Effects Of Annealing/Solution Treating And Aging On Longitudinal And Transverse Properties Of Ti-6al-4v Forgings, Blake Reller

Materials Engineering

Forty-eight subsize round-bar tensile samples (ASTM E8) were machined from 3-in-thick forgings of Ti-6Al-4V. Half of these samples were cut so the axis aligned with the longitudinal (LG) direction of the forging, the other half were cut to align with the transverse (LT) direction. Four samples from each direction were subjected to one of six heat treatments so that a total of eight samples received each treatment. Annealed samples were held at 1350°F for two hours, then air cooled. Solution treated and aged (STA) samples were solution treated at one of five temperatures between 1785°F and 1435°F for one hour …

Materials Characterization Of Bamboo And Analysis Of Bonding Strength And Internal Strength As A Structural Member In Reinforced Concrete, Nithi Plangsriskul, Nicholas Dorsano

Materials Engineering

This study evaluates the potential to utilize bamboo as reinforcement in concrete structural members. In this project, the mechanical properties of bamboo were tested, specifically force required to embed a 0.5” diameter ball 0.016” into the bamboo samples and its bonding strength with concrete. One type of bamboo, Bambusa Oldhamii, was cut into eight sections, approximately 2.54 cm wide, along the length of the culm. The compression test recorded the bamboo’s strength at eight points along the length of the internode and at three points along the transverse direction of each specimen. Bambusa Oldhamii’s specimen base 1 data for inner, …

The Effects Of Cure Schedule On Properties Of Glass-Fiber Reinforced Epoxy Matrix Composites, Trevor J. Lee

Materials Engineering

Two different two-component resin systems were cured, via Differential Scanning Calorimetry, for the times recommended by their respective manufacturers. The resin cure schedules were designed to simulate typical and attainable processing conditions; they were cured at 120°F, 140°F, and 160°F, and in-mold post-cured at 200°F, 230°F, and 260°F. The resulting scans were then compared to a baseline cure for each resin system, consisting of two heating-cooling cycles at a constant rate of temperature change. These baseline cures were then used to determine the percent cure of each sample and the shift in glass transition temperature between the baseline cure and …

Investigating The Mechanical Properties Of Compression Molded Carbon Fiber Reinforced Sheet Molding Compound, Bradley A. Jones

Materials Engineering

Callaway Golf receives a proprietary blend of prepreg material from Quantum Composites. Callaway processes the prepreg in-house and supplied 254mm x 254mm x 1.3mm panels of carbon fiber sheet molding compound (CFSMC) for characterizing. Tensile strength was analyzed by conducting tensile tests per ASTM D3039. Tensile coupons were cut to 254mm long by 25.4mm wide. Tabs were constructed from 1.6mm thick GFRP printed circuit board material. A commercial grade two part epoxy was used to bond the tabs to the CFSMC. Tensile results were inconclusive due to consistent fractures occurring outside the gauge lengths of the specimens.

Flexure strength was …

Characterization Of The Relationship Between The Microstructure And Tensile Strength Of Annealed Ti-6al-4v, Aldo Corona

Materials Engineering

Tensile coupons of Ti-6Al-4V were heat treated at varying annealing temperatures from 1200°F (648°C) to 1450°F (787°C) at 50°F (23°C) increments for 1 hour. The samples were air cooled to room temperature or furnace cooled to 800°F (426°C) followed by air cooling to room temperature. Four tensile coupons were treated at each annealing temperature and cooling rate. Alpha case was observed to form on the surface of the samples post heat treatment with a maximum depth of 25 µm (.001 in). Samples were tensile tested for their ultimate tensile strength, yield strength, and percent elongation. Samples across all annealing temperatures …