Mechanical Engineering Commons^™

Effect Of Prefilmer Design On Atomization Behavior In The Pre-Vaporization Tube Of A Small-Scale Annular Gas Turbine Combustior, Amogh G. Natu, Antoine M. Fradet, Cohen Nunes, Daniel R. Guildenbecher

School of Mechanical Engineering Faculty Publications

This work investigates the influence of internal prefilmer geometry on fuel spray atomization in the prevaporization tube (PVT) of a small-scale reverse-flow annular gas turbine combustor. Four configurations are examined: a control with no prefilmer, a planar internal prefilmer, and two angled internal prefilmers at θ = 60◦ and θ = 45◦ . Double-pulsed digital in-line holography (DIH) is used to measure droplet size distributions, spray density, Sauter mean diameter (SMD), and droplet velocities at the PVT exit under conditions scaled to represent nominal ignition conditions. Results show the control design exhibits poor atomization characterized by large droplet diameters, low …

Model-Based Investigation Of The Influence Of Environmental Conditions On The Energy Supply Of Multirotor Uavs, Morten Roßberg, Hanna Dibbern, Claudia Werner

Journal of Aviation Technology and Engineering

Flight time of unmanned aerial vehicles (UAVs) is limited by available energy, which is affected by the mission profile and external factors, such as environmental conditions. Two main environmental conditions that need to be considered are the impact of wind and ambient temperature on the UAV and its energy supply. The purpose of this study is to examine the effects of wind and ambient temperature to conduct a preliminary evaluation of flight performance and flight limitations. For this reason, three locations in the United States—New York City, Miami, and Fairbanks—are selected and the impact of the considered environmental conditions of …

Impact Of Slot Liner Compression On The Total Thermal Resistance Of The Stator-Winding Assembly In Electric Motors, Lindsay Sutherland

The Journal of Purdue Undergraduate Research

The increasing demand for high-performance electric motors, driven by the rapid adoption of electric vehicles, necessitates effective thermal management techniques that improve their safety, efficiency, and reliability. Heat must be transferred from the current-carrying copper windings to the metallic stator body through an electrically insulating material called the slot liner. However, little research has focused on the interactions between the slot liner and the windings. This study examines the impact of slot liner compression on the thermal resistance across the stator-winding assembly considering two common slot liners: Nomex® 410 and Kapton® MT+. A mock stator-winding assembly was developed by stacking …

Hydrogen Embrittlement In Shot-Peened Steel, Jia-Huei Tien, David R. Johnson, David Bahr

15th International Conference on Shot Peening

This work investigates the role of shot peening on hydrogen embrittlement resistance in quenched and tempered 1070 steel. Thermal desorption spectroscopy results revealed that shot-peened specimens contained nearly twice the hydrogen (H) content of unpeened samples when charged under the same electrochemical conditions, suggesting the introduction of additional trapping sites occur during peening. The mechanism underlying this behavior can be associated with increased dislocation density and is more consistent with the HELP mechanism. Residual stress measurements show a significant relaxation of compressive stresses in shot-peened specimen after H charging, indicating H enhanced dislocation rearrangement. Both unpeened and peened specimens exhibited …

Anisotropic Residual Stress Measurements In Additively Manufactured 316 Stainless Steel Parts, Rajeshree Varma, Donovan Stumpf, Paul R. Mort

15th International Conference on Shot Peening

Additive manufacturing (AM) using laser powder bed fusion (L-PBF) is increasingly used to produce complex parts for industries like aerospace and medical devices. The intrinsic characteristics of AM – layer-wise deposition and rapid thermal cycling – generate significant, anisotropic, residual stresses that can compromise part quality and performance. Recent studies highlight how these stresses are strongly influenced by process parameters and build orientation. X-ray diffraction (XRD) techniques, including sin²ψ and advanced two-dimensional approaches, have become the preferred methods for non-destructive, directionally resolved measurement of residual stress in AM metals. This review surveys advancements in XRD residual stress methods with a …

From Strain To Stress: Stress Map Testing Of Almen Strips, Donovan Stumpf, Rajeshree Varma, Paul R. Mort

15th International Conference on Shot Peening

Almen strips have long been used to evaluate shot peening intensity, with arc height serving as a proxy for compressive residual stress. Stress mapping tests (SMT) in this work involve the controlled flattening of an Almen test strip onto a spatial pressure sensor, acting as an inferential measurement for the net bending moment caused by the relaxation of the peened strip. This work explores how stress mapping tests add insight into the stress state of Almen strips, potentially offering a fast and practical alternative to residual stress depth profiling. SMT data analysis provides a framework for relating Almen gauge height …

Fourier Analyses Of Optical Profilometry As An Inferential Measurement For Impact Coverage., Langdon Feltner, Paul Mort

15th International Conference on Shot Peening

A critical consideration in peening process design is achieving sufficient impact coverage. Conventional methods for assessing coverage rely on manual inspection, which is time-consuming and poorly suited for automated control. In this work, we investigate the use of frequency-domain analysis to quantify surface modification in peened samples using optical profilometry (OP) data. Three-dimensional surface maps of Almen strips were acquired using a high-resolution OP system and analyzed via fast Fourier transform (FFT) to compute spatial power spectral densities (PSDs). PSD maps and radially averaged profiles reveal consistent amplification of harmonic components similar to the nominal particle size, with increasing intensity …

Enhancing High Cycle Fatigue Perfomance Of Electron Beam Melted Ti6al4v: A Study On Shot Peening And Hot Isostatic Pressing, Naghmeh M. Mojib, Dwayne D. Arola, Ramulu Mamidala

15th International Conference on Shot Peening

The qualification of electron beam powder bed fusion (PBF-EB) for safety-critical applications is hindered by variability in high cycle fatigue performance, largely due to surface roughness and internal defects. While Hot Isostatic Pressing (HIP) effectively reduces internal porosity, it does not address surface-initiated fatigue failures. This study investigated the combined effects of HIP and shot peening on enhancing the fatigue performance of PBF-EB Ti6Al4V. Over 50 specimens, including both vertical and horizontal build orientations, underwent high cycle fatigue testing per ASTM E466. X-Ray computed tomography confirmed decrease in defect distribution following HIP, while shot peening resulted in a more uniform …

Comparison Of Peening Effect Between Additive Manufacutred And Drawing Titanium Alloy, Hitoshi Soyama

15th International Conference on Shot Peening

Although additively manufactured (AM) metals are attractive materials, their remarkable weak fatigue properties are an obstacle to their practical application. Thus, post-processing to improve their fatigue properties is required. In the present study, powder bed fusion using laser sintering titanium alloy, i.e., PBF-LS/Ti6Al4V was treated by shot peening (SP), submerged laser peening (SLP), cavitation peening (CP), and fine particle bombarding (FPB), then the fatigue properties were investigated by a torsional fatigue test, comparing with drawing Ti6Al4V. It was revealed that the fatigue strength at 10⁷ was 446 ± 5 MPa for PBF-LS/Ti6Al4V treated by FPB+CP, 359 ± 9 MPa …

Reduced Order Approach For Peening Stress Field Variability, Langdon Feltner, Paul Mort

15th International Conference on Shot Peening

A common goal in shot peening research is to connect operational parameters to resultant residual stress fields, providing a means to control and optimize the effectiveness of surface treatment. In practice, experimental measurements of residual stresses are often averaged values over regions that are large in comparison to an impact dimple. In fact, the stochastic nature of impact locations leads to residual stress fields that are distributed. Finite element peening simulations confirm this observation. The goal of this report is to connect operational parameters to localized fluctuations in residual stress through probabilistic reasoning (Figure 1). In particular, the development of …

Adaptation Of Shot Peen Parameters For Gear Geometry, David J. Breuer, Beth Matlock

15th International Conference on Shot Peening

Shot peening is a well established process for the surface enhancement of gearing. Gearing is a primary example of a high cycle fatigue application that can benefit from residual stress enhancement. Designing shot peening parameters to specific gear geometry based on material, heat treatment, and surface finish is a more precise way to achieve better performance outcomes. One of the best tools to assist in the optimal shot peening is x-ray diffraction (XRD) and its ability to measure small differences that can result in significant performance outcomes. XRD residual stress measurements are a direct measurement of elastic strain. The diffraction …

Investigations On The Fatigue Strength Of Threads Produced By Different Fabrication Techniques, Philippe Du Maire, Jürgen Hoffmeister, Andreas Öchsner, Michael Johlitz

15th International Conference on Shot Peening

The increasing importance of sustainability in engineering demands the development of long-lasting, high-performance components that reduce material and energy consumption over time. This study investigates how different thread manufacturing processes, i.e., cutting, rolling, and deep rolling, affect the fatigue strength of bolts made from 42CrMo4+QT steel. Cylindrical specimens with M12 threads were subjected to cyclic tensile loading with constant mean stress. Fatigue strength was evaluated using the staircase method, and supporting analyses included X-ray diffraction for residual stress, and full width half maximum examination and Vickers microhardness measurements. Results show that thread rolling significantly improves fatigue strength, achieving 113.8 MPa …

Numerical Assessment Of Shot Peening Contribution To The Fatigue Strength Of Gear Tooth Root, Gurutz Cortabitarte Laucirica, Xuban Telleria, Iñigo Llavori, Ibai Ulacia, Miren Larrañaga, Jon Ander Esnaola

15th International Conference on Shot Peening

Gears are commonly treated with shot peening (SP) and/or case hardening to enhance fatigue resistance. However, their effects are often conservatively assessed using standardized methods, which can limit their optimal application in industrial components. Particularly, the effect of SP over case-hardened gears remains insufficiently explored. Therefore, the present study evaluates the contribution of SP on single tooth bending fatigue (STBF) strength of raw and case-hardened spur gears, commonly used in automotive and heavy machinery industries. In the study four conditions are addressed: (i) untreated, (ii) case-hardened, (iii) shot-peened, and (iv) case-hardened and shot-peened. First, the residual stress field of the …

Effect Of Fine Particle Peening Induced Material Transfer On The Initial Deposition Behavior Of Nickel Electroplating On Aluminum Substrate, Kazuki Iijima, Yutaka Kameyama, Hideaki Sato, Shuhei Kodama

15th International Conference on Shot Peening

Plating on aluminum requires a complex zincate pretreatment. Fine Particle Peening (FPP), using particles ≤200 µm, has gained attention as an alternative due to its ability to transfer particle components onto the surface, potentially improving deposition and adhesion. Previous studies showed enhanced plating on aluminum treated with steel particles. This study investigates the effectiveness of FPP as a pretreatment for nickel electroplating by examining initial deposition behavior. A1050-H24 aluminum was treated using FPP with either steel or glass particles, compared to an untreated specimen. Steel particle FPP created a lamellar microstructure with alternating iron and aluminum phases. EBSD revealed that …

The Effect Of Surface Treatment On The Fatigue Strength Of Sus316l Additive Manufactured Products, Hitoshi Nishijima, Yuji Kobayashi, Toshiya Tsuji, Kiyotaka Masaki

15th International Conference on Shot Peening

Rotating bending fatigue tests were conducted to investigate the effect of shot peening and barrel finishing on fatigue properties of SUS316L made by laser PBF which was one of additive manufacturing processes. Surface roughness, residual stress, and fatigue strength were investigated for each specimen. As a result, the fatigue strength of the barrel finished specimens was almost same or better than that of the shot peened specimens. Barrel finished specimens increased 4.1 times higher fatigue strength than as-built specimens. The surface roughness of the specimens after barrel finishing was reduced by up to 96% compared to the as-built specimens. On …

Expansion Of Laser Peening Application With A High-Power Microchip Laser On A Robotic Arm, Yuji Sano, Yoshio Mizuta, Satoshi Tamaki, Tomonao Hosokai, Tomoharu Kato, Yoshihiro Sakino, Volker Schneidau, Sebastian Holz, Jörg Behler

15th International Conference on Shot Peening

Laser peening (LP) introduces compressive residual stress (RS) onto the surface of metallic materials using nanosecond laser pulses irradiated through a water layer, thereby effectively suppressing fatigue crack initiation. However, conventional LP systems require large, stationary setups, restricting their use to indoor environments. To overcome this limitation, a portable LP device featuring a finger-sized microchip laser mounted on a collaborative robot arm has been developed. Equipped with a compact power supply and a water circulation/recovery system, the device can operate on-site with minimal setup. Successful processing across various materials has confirmed both compressive RS induction and fatigue life extension. Notably, …

Effects Of Laser Peening On Fatigue Properties Of Welded Aluminum Thin Plates, Kiyotaka Masaki, Yoshio Mizuta, Satoshi Tamaki, Yuji Sano

15th International Conference on Shot Peening

To improve the fatigue properties of welded aluminum alloy thin plates used in transportation machinery, handheld laser peening (HH-LP) was applied to 2 mm-thick A5083-O specimens prepared by bead-on TIG welding. Conventional laser peening often causes warping in thin plates, but the HH-LP treatment using low-energy laser pulses avoids this problem. The HH-LP treatment introduced compressive residual stresses of over 200 MPa on the heat-affected zone (HAZ) of the welded specimens. Fatigue tests under plane bending conditions revealed that the HH-LP treatment significantly improved the fatigue strength of the welded specimens, achieving a level comparable to that of the base …

Evaluation Of Peening Intensity With Nozzle-Mounted Sensor During Processing, Akinori Matsui, Shuji Hayashida, Yuji Kobayashi

15th International Conference on Shot Peening

In recent years, digital technologies have been increasingly applied in manufacturing, including visualization and anomaly detection in production equipment. In shot peening, Peening Intensity is a key process control indicator, but its measurement requires significant manual effort. This study aims to evaluate the possibility of using an AE-sensor-mounted nozzle to estimate Peening Intensity. We conducted experiments comparing sensor outputs with experimented Intensity under controlled conditions. A strong correlation (R² ≥ 0.95) was observed, suggesting that Peening Intensity can be estimated via AE sensing. This approach may contribute to labor-saving and automation in shot peening processes.

Comparison Of Anti-Fouling Performance Of Textured Glass Surface Fabricated By Ductile-Mode Peening And Precision Grinding, Hayato Tagaya, Yutaka Kameyama, Shuhei Kodama, Hideaki Sato, Kento Shinagawa, Ayumu Sekiguchi, Seiji Hirai, Hitoshi Ohmori

15th International Conference on Shot Peening

Recently, there has been a growing demand for precision processing glass. In addition to dimensional accuracy, surface texturing to impart functional properties has attracted increasing attention. For example, anti-fouling performance against powder adhesion is required for cover glasses of solar cells. Powder adhesion is governed by van der Waals forces, which depend on the surface texture of the substrate, suggesting that surface structures influence adhesion behavior. Our previous study demonstrated that angled fine particle peening (FPP) could fabricate a nanoscale fine texture on glass surfaces through ductile-mode peening—glass processing without brittle fracture. In this study, the effect of surface texturing …

The Use Of A Dynamic Imaging System To Characterize Particle Size And Shape For Shot Peening Media, Matthew Spink, Tod Canty, Langdon Feltner, Paul Mort

15th International Conference on Shot Peening

Shot peening is a cold working process that enhances the mechanical properties of components such as springs, axles, and gears. Shot media are projected at a high velocity against the material’s surface, creating a layer of compressive residual stress that improves fatigue and wear resistance of the material. The size and shape of the media affect the residual stress layer that is created. To ensure consistent quality, it is critical to characterize and control the particle size and shape distribution of the shot media, both as-manufactured and in the working mix. This paper presents how the use of a dynamic …

Microstructural Changes And Residual Stress Generation On The Periodically Patterned Surface Texture Fabricated By Angled Fine Particle Peening, Yutaka Kameyama, Hideaki Sato, Ryokichi Shimpo

15th International Conference on Shot Peening

Focusing on the potential of peening technology as a surface texturing technique, angled fine particle peening (angled-FPP) has been proposed to fabricate a specific periodical surface structure, which possibly provides various surface functions. It is necessary to further characterize the textured surface to earn more advantages from angled-FPP. Thus, in this paper, texture formation phenomena, residual stress, and microstructural changes were investigated on the angled-FPP specimens.

Roughness Parameters For Evaluating Blasted Or Shot Peened Surfaces, Stefanie Stoeckel, Sophie Groeger

15th International Conference on Shot Peening

A review of the papers presented at the last three International Conferences on Shot Peening revealed that the most used parameters are Ra and Rz. There has been comparatively little exploration of other parameters, particularly the S-parameters. Furthermore, the ISO 4287 standard for profile parameters was replaced by the new ISO 21920-2 standard in 2021. This is accompanied by the introduction of new parameters as well as alterations to existing ones. This paper demonstrates the limitations of Ra and Rz, as well as Sa and Sz, and explores additional areal and profile parameters that are useful for the description of …

Improving Fatigue Strength And Life Of Single Crystal Cmsx-4, Jochen Peter Fuhr, Lloyd Hackel, Nicolau I. Morar, Noah Holtham, Keivan Davami, Montu Sharma, Rajkumar Roy

15th International Conference on Shot Peening

The deep penetration of laser peening (LP) and retention of residual stress at high temperature by LP is significant in improving fatigue life and strength of superalloys exposed to high temperature and corrosion. Single crystal CMSX-4, was evaluated for stress relaxation and both fatigue life and fatigue strength of material that was LP-treated compared to non-LP and shot-peened (SP) specimens. LP was done with multiple layers using a 20 J/pulse laser where the laser high energy enabled using a 5 mm spot size on the metal surface. Stress measurements by the slitting technique showed the plastic penetration depth exceeded SP …

Application Of Burnishing Process Expected To Frictional Heat To Non-Oriented Electromagnetic Steel Sheet, Yuji Kobayashi, Masato Okada

15th International Conference on Shot Peening

Burnishing is a technology used to improve the surface roughness of metals. On the other hand, it is expected that the metal structure near the surface will change due to strong distortion.

The magnetic properties of electromagnetic steel sheets depend on large crystal grains and fine crystals near the surface[1]. In particular, thinner fine crystal grain layers on the surface are expected to reduce iron loss. In this study, the power generation characteristics of Burnished electromagnetic steel sheets were evaluated.

Electromotive force waveform was evaluated by rotating the laminated electromagnetic steel sheets and using a spindle motor. The electromotive force …

The Effects Of Shot Peening Highly Loaded Compression Springs, David J. Breuer

15th International Conference on Shot Peening

The compression spring in this test study is typical of one used in a demanding off-road vehicle suspension. The cyclic loads applied during fatigue tests were severe enough to cause failure in approximately 11,000 cycles without shot peening.

The objectives of this study were the following: (1) Design a compression spring similar to those used in the off-road recreational industry. (2) Design & manufacture a fatigue test stand that could withstand high loads for months of testing. (3) Generate a matrix of shot peening treatments to produce different amounts of residual compressive stress. (4) Measure the shot peening residual compressive …

Is There A More Effective Design For Quadrat To Increase Ease Of Use And Vegetation Density?, Scott M. Burke Jr., Kristen M Bellisario

Discovery Undergraduate Interdisciplinary Research Internship

Quadrats are a special tool in the ecology field that allows the measurement of vegetation density for further data analysis of a habitat. The larger the quadrat cross-sectional area, the better the results of the data, which in turn can make the quadrat hard to carry through field sites. In wildlife corridor research, quadrat surveys provide a quantitative metric for habitat suitability. In this work, we consider the efficiency and ease-of-use benefits for field work in the design of a collapsible version of a quadrat using a House of Quality (standard metric for new design requirements) to assess the customer …

Photocatalytic Self-Pumping Membranes, Lily D. Farmer, David Warsinger, Sudharshan Anandan

Discovery Undergraduate Interdisciplinary Research Internship

The physics of nanofiltration is not well understood, as many types of membranes and filters exist, but they all interact very differently with the substance they are filtering. This research investigates membranes that can autonomously pump fluid through catalytic reactions. The first set of experiments was to collect zeta potential measurements as zeta potential is a critical property that directly affects fluid transport. Zeta potential was measured using the Anton Parr SURPASS 3, which measures the sample by streaming a given solution through a channel of membranes and uses the Smoluchowski equation to return the zeta potential value. Measurements were …

The Spice (Sustainable, Physics-Inspired Culinary Education) Lab – A Digestible Few-Nexus Educational Platform, Carla Ramsdell

National Collaborative for Research on Food, Energy, and Water Education (NC-FEW)

The SPICE (Sustainable, Physics-Inspired Culinary Education) Lab is a unique educational platform that enables participants from a wide disciplinary background to engage and become literate in the unique connections between food, energy and water. This small but mighty space allows for outreach education in many formats, including formal college courses, university-centered hands-on activities and public outreach.

The work performed in this space fills a unique need in the FEW-Nexus education opportunities because it is adaptable to many learners and learning opportunities and its focus on kitchen science makes these concepts approachable which can later be expanded to understand other critical …

Iros 2023 Workshop Report: Draft Guidelines On Manufacturing Procedures, Test Methods And Reporting For Soft Robotics, Robert Baines, Laura Blumenschein, Jennifer Case, Robert Maccurdy, Gina Olson, Andrew Spielberg

School of Mechanical Engineering Working Papers

No abstract provided.

Experimental Comparison Of Cycle Modifications And Ejector Control Methods Using Variable Geometry And Co2 Pump In A Multi-Evaporator Transcritical Co2 Refrigeration System, Gabriele Toffoletti, Riley Barta, Steven M. Grajales, Haotian Liu, Davide Ziviani, Eckhard A. Groll

School of Mechanical Engineering Faculty Publications

To reduce the direct global warming impact of refrigerants in HVAC&R applications, low-global warming potential (GWP) refrigerants, including natural refrigerants, have been extensively investigated as alternatives to hydrofluorocarbon (HFC) refrigerants. Among the natural refrigerants, Carbon Dioxide (CO2) offers several advantages, such as excellent transport and thermo-physical properties, being neither toxic nor flammable, and having a low price and high availability around the world. However, the high critical pressure and low critical temperature of CO2 often lead to transcritical operation, resulting in lower efficiency due to the additional compressor power necessary to achieve transcritical operation relative to subcritical HFC cycles. Therefore, …