About

Professor Kiran D'Souza is a faculty member in the Department of Mechanical and Aerospace Engineering at The Ohio State University and serves as the director of the Nonlinear Dynamics and Vibration Lab. His research focuses on fundamental nonlinear dynamics modeling and analysis, reduced order modeling, and the analysis of complex high-dimensional cyclic structures found in turbomachinery. He also works on modeling of complex nonlinear systems, system identification, structural health monitoring, nonlinear feedback control for enhanced sensitivity in detection and sensing, bifurcation forecasting, and large-scale rotating turbomachinery experiments at design conditions. Professor D'Souza is the Associate Director of The Ohio State University's Gas Turbine Laboratory (GTL), which aims to advance gas turbine design through a combination of academic and industrial research utilizing computational and experimental techniques. He earned his BS in 2003, MS in 2004, and PhD in 2009 in Mechanical Engineering from the University of Michigan, where he also completed postdoctoral research and served as a Research Scientist at the Vibration and Acoustics Lab until 2014. His key contributions include analyzing complex nonlinear dynamics in turbomachinery and developing techniques to efficiently model, analyze, and exploit nonlinearity in large-scale rotating systems.

Selected publications

• Bladed Disk Reduction for Transient Loading in Blade Tip Rubs and Foreign Object Ingestion

  Journal of vibration and acoustics · 2026-01-22

  articleSenior author

  Abstract Nominal bladed disk models are designed as cyclically symmetric structures that can be analyzed using single-sector models to reduce the computational expense. This type of analysis is effective for many structural analyses including generating Campbell diagrams and analyzing the response to engine order excitations. However, the response to transient asymmetric excitation (e.g., due to blade tip rubs or foreign object ingestion) cannot currently be analyzed efficiently. In this work, a new methodology is presented that constructs reduced-order models using only sector-level models and calculations that can be used to compute the time-resolved dynamics of active nodes chosen during the reduction. The methodology keeps the active nodes in the physical coordinate system, while modally reducing the rest of the system. This allows for easy coupling between the dynamics of the active nodes and any modeling that could be involved in determining time-dependent forcing vectors, like an abradable liner wear model in the specific case of blade tip rubs. The presented model is validated for four different forced response solutions representing realistic forcing cases for both blade tip rubs and foreign object ingestion events, showing high levels of agreement between the proposed method’s solutions and full finite element solutions obtained from commercially available finite element solvers. The presented method allowed the forced response solutions to be completed two to three orders of magnitude faster than the full finite element solutions, for the academic bladed disk studied, with greater speed increases expected for larger industrial models.

  PublisherDOI

• A Dual Piezoelectric Vibration Energy Harvester With Controllable Gap Size Using Piecewise Nonlinearity

  Journal of Computational and Nonlinear Dynamics · 2026-02-19

  articleSenior author

  Abstract For the past decade, vibration energy harvesting has gained increasing interest. Numerous approaches have been developed to capture unused energy from physical vibration sources, such as ocean waves, buildings and bridges. This paper introduces and evaluates a dual piecewise-linear (PWL) piezo-electric energy harvester design. A prior study involving a single piezo-electric cantilever beam with a mechanical stopper demonstrated that optimizing the gap size could enhance energy generation. This work replaces the mechanical stopper with a second piezo-electric cantilever beam to further improve the performance of PWL piezo-electric harvesters. A new two-degree-of-freedom model is proposed and analyzed both computationally and experimentally. Moreover, an enhanced methodology is employed to identify system dynamics from experimental measurements. A simple controller is created and implemented to experimentally validate the computational model. The results demonstrate improved overall performance and a broader operating frequency range for the proposed energy harvester.

  PublisherDOI

• Bladed Disk Reduction for Transient Loading Seen in Blade Tip Rubs

  2025-08-17

  articleSenior author

  Abstract Minimizing blade tip clearance has become a main point of interest in the optimization of gas turbine engines. As such, there has been extensive work in reducing the size of the tip clearance to the point that the blades may contact the engine casing. To ensure safe operation, engine manufacturers have added a sacrificial abradable coating to the casing, to protect the blades in the event of a rub event. Understanding the interaction of the blade tip with the liner during rub events is imperative for ensuring the durability and life of the engine hardware. Much work has been completed both experimentally and computationally to examine just that. The current work focuses on efficiently modeling the dynamics of a bladed disk under realistic blade tip rub forcing. A new methodology is presented that constructs compact reduced order models using only sector level models and calculations that can be used to compute the time resolved dynamics of the blade tips during the rub event. The methodology keeps the blade tip nodes in the physical coordinate system, while modally reducing the rest of the system. This allows for easy coupling between the dynamics of the blade tip and any modeling that could be involved in solving for time dependent forcing vectors, like an abradable liner wear model in the specific case of blade tip rubs. The presented model is validated for three different forced response solutions, showing high levels of agreement between the proposed method’s solutions and full finite element solutions obtained from commercially available finite element solvers.

  PublisherDOI

• A generalized model of mistuning for bladed disks

  Journal of Sound and Vibration · 2025-02-27 · 8 citations

  articleOpen accessSenior authorCorresponding

  Bladed disks always have variations between blades, known as mistuning, which is a large focus of research within the turbomachinery industry. When mistuning is present, the forced response shows localized amplification of blade responses. Due to the random nature of these variations, statistical analyses are conducted to understand sensitivity to mistuning. For high-dimensional models this is an intractable problem unless the model is reduced. To this end, reduced order models have been developed that enabled projection of mistuning to reduce computational expenses. These methods include techniques for reducing systems with many types of mistuning including modulus and geometric variations. This work creates a generalized model of mistuning (GMM) that incorporates mistuning into the blade or disk. The GMM method has many of the benefits of previous mistuning models by being compact and only requiring sector level models. GMM utilizes an augmented Craig-Bampton component mode synthesis to decouple the blade and disk. These models are then projected onto a reduced modal space with mistuning applied. The combination of the blade and disk reduction occurs through the projection of the interface onto special disk-blade interface modes. Validation is performed for a few types of mistuning (e.g. stiffness, damping, geometric) to demonstrate the effectiveness of GMM. • A generalized model of mistuning (GMM) for bladed disks is presented. • GMM can then project any number of forms of mistuning onto a reduced modal space. • A validation is done for many types of mistuning to show the effectiveness of GMM.

  PublisherDOI

• Controllable Piecewise Linear Dual Piezoelectric Cantilever Beams for Energy Harvesting

  2025-08-17

  articleSenior author

  Abstract Recently, vibration energy harvesting has gotten increased attention. Various methods have been developed to collect unused energy from physical vibrations sources such as ocean waves. This paper presents and tests a dual piecewise-linear (PWL) piezoelectric energy harvester design. A previous study was conducted with a single piezoelectric cantilever beam with a mechanical stopper and showed the potential to improve the energy generation of piezoelectric energy harvesters by controlling the gap size. This work further improves the performance of PWL piezoelectric energy harvesters by replacing the mechanical stopper with another piezoelectric cantilevered beam. A new two degree-of-freedom model is proposed and investigated both computationally and experimentally. The good agreement between the bench-top system and the computational simulations validates the new computational approach. This paper also uses an improved methodology to identify the system dynamics from the experimental measurements. An improvement in both overall performance and operating frequency range of the new energy harvester is demonstrated in this work.

  PublisherDOI

• Exploiting Piecewise Linearity in Wave Energy Converters

  2025-08-17

  articleSenior author

  Abstract Researchers have developed many ways to scavenge energy from mechanical, thermal, and other previously-unused energy sources. Among these sources, ocean waves are a predictable energy source, making them an important field in renewable energy. A class of energy harvester referred to as Wave Energy Converters (WECs) operates at the surface of the ocean and harness energy from wave motion. This work focuses on improving the power output of WECs using a piecewise linear (PWL) system. Previous studies have been conducted on improving the performance of electromagnetic energy harvesters by incorporating an adjustable gap in the PWL system. This work explores the effect of introducing an adjustable mechanical stopper to the WEC system. The performance of the adjustable stopper is tested in the Wave Energy Converter Simulator (WEC-Sim), open-source software for simulating WECs. A comparison between the PWL WEC and the original WEC based on the same reference model shows a 25% average power output increase in the PWL WEC, depending on the sea state. A simple controller is used with the pre-computed steady-state sea responses to improve the power output. The controller is tested in noisy and quasi-static sea states to compare the novel WEC against the baseline uncontrolled WEC.

  PublisherDOI

• Capturing Mistuning Within Shrouded Integrally Bladed Disks With the Generalized Model of Mistuning

  Journal of Engineering for Gas Turbines and Power · 2025-09-11

  articleSenior author

  Abstract Bladed disks and blisks are designed to be cyclic structures that ideally have identical sectors. There will, however, always be mistuning, which is blade-to-blade differences that break the cyclic symmetry of the system and can result in an increase in vibrational amplitudes. Many different methods for producing reduced order models (ROMs) have been developed, with each generally designed to accurately capture a particular form of mistuning that is present. For high-dimensional finite element (FE) models, ROMs are needed to perform many structural dynamic calculations quickly. These ROMs are also required to perform any statistical analysis to characterize random mistuning. Recently, a generalized model of mistuning (GMM) method was developed that enables efficient construction of ROMs that can readily capture multiple forms of mistuning in bladed disks simultaneously. GMM has been demonstrated to be an effective way to model mistuning separately in the blade and disk, where the mistuning can be any combination of damping, small or large stiffness, or geometric mistuning. This work extends GMM to capture systems that contain shrouds and dual flow path (DFP) blisks with multiple sources of mistuning. GMM uses only single-sector models and calculations in the construction of the ROM, allowing realistic industrial models to be analyzed. For each of the systems studied, GMM is validated using a full-stage finite element model.

  PublisherDOI

• Capturing Mistuning Within Shrouded Integrally Bladed Disks With the Generalized Model of Mistuning

  2025-06-16

  articleSenior author

  Abstract Bladed disks and blisks are designed to be cyclic structures that ideally have identical sectors. There will, however, always be mistuning, which is blade to blade differences that break the cyclic symmetry of the system and can result in an increase in vibrational amplitudes. Many different methods for producing reduced order models (ROMs) have been developed with each generally designed to accurately capture a particular form of mistuning that is present. For high dimensional finite element models, ROMs are needed to perform many structural dynamic calculations quickly. These ROMs are also required to perform any statistical analysis to characterize random mistuning. Recently, a Generalized Model of Mistuning (GMM) method was developed that enables efficient construction of ROMs that can readily capture multiple forms of mistuning in bladed disks simultaneously. GMM has been demonstrated to be an effective way to model mistuning separately in the blade and disk where the mistuning can be any combination of damping, small or large stiffness, or geometric mistuning. This work extends GMM to capture systems that contain shrouds and dual flow path blisks with multiple sources of mistuning. GMM uses only single sector models and calculations in the construction of the ROM, allowing realistic industrial models to be analyzed. For each of the systems studied GMM is validated using a full stage finite element model.

  PublisherDOI

• A Broadband Piezoelectric Energy Harvester With Robust Control Using Piecewise Nonlinearity

  Journal of Computational and Nonlinear Dynamics · 2025-02-22 · 2 citations

  articleSenior author

  Abstract Research in the field of vibration energy harvesting has been increasing over the past decade. Researchers have developed various methods to collect unused or wasted energy from physical systems, such as bridges. This paper presents and tests a piecewise-linear (PWL) piezoelectric energy harvester design. Similar studies have been conducted for an electromagnetic energy harvester and have shown the benefit of implementing a PWL energy harvester for some potential applications. This work investigates the performance of the PWL energy harvester using a piezoelectric cantilever beam as the energy generator, which is more suitable for smaller-scale harvesting applications. The design of the piezoelectric cantilever beam system uses a simple control algorithm to maintain the optimal gap size in the system. This design actively adjusts the resonance frequency to maximize power generation over a larger frequency range to make self-powered sensors more viable. The resonance frequency is optimized by adjusting the gap size between the piezoelectric cantilever beam and an elastic stopper using a combination of linear actuators, circuits, and microprocessors. The design shows an increased performance in maintaining an optimized vibration amplitude in the precomputed frequency range. An experimental realization of the design is tested and compared with the computational prediction to validate the design’s effectiveness.

  PublisherDOI

• An Optimization Method for Stiffness and Damping Mistuning Identification From Blade Tip Timing Data

  Journal of Engineering for Gas Turbines and Power · 2024-08-06 · 6 citations

  articleSenior author

  Abstract System identification of dynamic properties is of large interest in the turbomachinery industry to create more accurate computational models and more effective designs. Previous identification techniques are able to accurately capture the blade variability, known as mistuning, in the stiffness as well as the average damping of all the blades. Mistuning is vital to accurately identify and study because the symmetry of the system is broken and can lead to vibration localization and high amplitudes. In this work, a new method is proposed to not only capture the stiffness mistuning values but also the blade-to-blade variability in damping. These damping mistuning values have been shown to have a significant effect on the dynamics of bladed disk systems. Incorporation of the damping mistuning into the computational model can be done utilizing an augmented component mode mistuning (CMM) method with either structural or proportional damping. The mistuning values for this new identification method were compared to a well-established direct method and a previously studied optimization method. Blade responses were then found using a harmonic analysis and the newly identified mistuning values. These blade responses were then compared to experimental tip timing data from full scale rotating experiments. These comparisons show that the new model is able to better reproduce experimental data using computational models that incorporate both stiffness and damping mistuning values.

  PublisherDOI