Daniel Inman

• PhD ME; MAT Physics; BS Physics
• Professor at University of Michigan

A conventional galloping-based wind energy harvester is typically restricted to capturing energy from a single wind direction, making it inefficient in the unpredictable conditions of natural environments. This research presents comprehensive theoretical modeling of a novel galloping-based piezoelectric energy harvester featuring a tri-section beam...

The nonlinear energy sink (NES) is one representative nonlinear vibration absorber. Despite the existence of excitation threshold, it has been proven to be superior in terms of working frequency range and/or amplitude of vibration suppression, compared to the linear vibration absorber. In recent years, for single-degree-of-freedom NESs, multistable...

It was recently discovered that higher-order dynamics are intrinsically variational, in the sense that higher-derivative versions of the classical equations of motion can always be derived from a minimum-action principle similar to Hamilton’s principle, even when the physical system is non-conservative. This discovery has already led to several app...

Bird flight is often characterized by outstanding aerodynamic efficiency, agility and adaptivity in dynamic conditions. Feathers play an integral role in facilitating these aspects of performance, and the benefits feathers provide largely derive from their intricate and hierarchical structures. Although research has been attempted on developing mem...

In the field of rail transport and aerospace field, vibration energy harvesting is inevitably subjected to coupled excitations, including train wheel-track interaction induced friction heat and forced vibration, periodic thermal radiation, and vibration excitation. This paper investigates a coupled thermo-electric-elastic piezoelectric vibration en...

This study employs a high-fidelity numerical approach to simulate fluid–structure interaction phenomena for the dynamic response of flexible hyperelastic morphing wing structures under low aerodynamic loads. The computations are performed using the open-source solids4Foam toolbox, employing a partitioned two-way fluid–structure interaction approach...

Uncrewed aerial vehicles are integral to a smart city framework, but the dynamic environments above and within urban settings are dangerous for autonomous flight. Wind gusts caused by the uneven landscape jeopardize safe and effective aircraft operation. Birds rapidly reject gusts by changing their wing shape, but current gust alleviation methods f...

Expectations for uncrewed aerial vehicles (UAV) are expanding into new environments with dynamic challenges that negatively affect flight performance, such as gusts. Through wing morphing, fixed wing UAVs can rapidly adjust their lifting surfaces in response to perturbations. Here, we developed autonomous gust rejection controllers for a spanwise c...

This book provides a practical guide to understanding and designing dynamic vibration absorbers. Most of the material has been developed based on the authors' years of solving vibration problems using dynamic vibration absorbers and years of educating practicing engineers on the basic principles and techniques of dynamic vibration absorber design....

This paper reports the development of a hybrid piezohydraulic actuator. Piezoelectric stacks provide quick and precise response, when used as actuators. However, their small stroke limits their use to micro- and nano-actuation systems. Mechanical levers are most commonly used to amplify the displacement of a piezo stack, but they sacrifice a signif...

The interactions between ultrasonic waves and damage provide crucial information for developing effective damage detection techniques in various fields, including non-destructive testing and structural health monitoring, and they can be investigated through wave propagation. Then, this article presents an approach to investigate the longitudinal wa...

In this paper an ℋ∞ control algorithm is applied to design a feedback system for active wing/store flutter suppression. A two degree-of-freedom model of a typical section of an airfoil with an external store in incompressible flow is used for analysis. A state space representation is obtained by using a second order rational approximation of the co...

Some bird species fly inverted, or whiffle, to lose altitude. Inverted flight twists the primary flight feathers, creating gaps along the wing’s trailing edge and decreasing lift. It is speculated that feather rotation-inspired gaps could be used as control surfaces on uncrewed aerial vehicles (UAVs). When implemented on one semi-span of a UAV wing...

Despite its prevalence in neurosensory systems for pattern recognition, event detection, and learning, the effects of sensory adaptation (SA) are not explored in reservoir computing (RC). Monazomycin-based biomolecular synapse (MzBS) devices that exhibit volatile memristance and short-term plasticity with two strength-dependent modes of response ar...

There is a growing need for uncrewed aerial vehicles (UAVs) to operate in cities. However, the uneven urban landscape and complex street systems cause large-scale wind gusts that challenge the safe and effective operation of UAVs. Current gust alleviation methods rely on traditional control surfaces and computationally expensive modeling to select...

The design of structural health monitoring (SHM) systems usually involves the selection of actuators and sensors, defining their positions on the structure, and post-processing output signals. The definition of the characteristics of the excitation signals before investigating the structural condition is also an important task to be considered to e...

Structural Health Monitoring (SHM) techniques have an important role in the performance of mechanical structures. In particular, piezoelectric transducers (PZT) have been employed for establishing damage detection processes in SHM systems. However, despite their wide use, there is limited information in the literature regarding important characteri...

Many oscillatory systems of engineering and scientific interest (e.g., mechanical metastructures) exhibit non-proportional damping, wherein the mass-normalized damping and stiffness matrices do not commute. A new modal analysis technique for non-proportionally damped systems, referred to as the “dual-oscillator approach to complex-stiffness damping...

In the present work, we investigate dynamic interaction and response of flexible bio-inspired morphing wing structure to a low Reynolds aerodynamic load. The aspects of inspiration are as follows. First, the segmentation of the wing into rigid and flexible segments. Considering a leading edge constitution of bone and muscle. In addition to a flexib...

In the present work, we investigate dynamic interaction and response of flexible bio-inspired morphing wing structure to a low Reynolds aerodynamic load. The aspects of inspiration are as follows. First, the segmentation of the wing into rigid and flexible segments. Considering a leading edge constitution of bone and muscle. In addition to a flexib...

Metastructures, a metamaterial-type structure designed with distributed vibration absorbers, are a growing development in the area of passive vibration suppression. Previous research has shown that it is possible for vibration absorbers to be introduced into a structure for broadband vibration suppression without introducing additional mass. The pr...

Macro fiber composites (MFC) have proven useful as multifunctional material actuators for implementation in intelligent aerospace structures; however, due to nonlinear behaviors such as hysteresis and creep, incorporating sensor feedback is necessary to achieve sufficient control. In our work we use an antagonistic MFC unimorph system to produce a...

Several species of birds have been known to invert in flight to lose altitude — a behavior known as whiffling. When the bird flies inverted, the flight feathers twist open to create gaps in the trailing edge of the wing, decreasing the lift produced by the wing. Gaps along the trailing edge of an aircraft wing were inspired by the feather rotation...

Structural Health Monitoring (SHM) techniques have an important role in insuring the safe performance of mechanical structures and increasing their useable service time. However, despite the many advances in SHM, few results address the monitoring of interfaces connections. Thus, this article presents an approach to study longitudinal and flexural...

Smooth camber morphing aircraft offer increased control authority and improved aerodynamic efficiency. Smart material actuators have become a popular driving force for shape changes, capable of adhering to weight and size constraints and allowing for simplicity in mechanical design. As a step towards creating uncrewed aerial vehicles (UAVs) capable...

Smooth camber morphing aircraft offer increased control authority and improved aerodynamic efficiency. Smart material actuators have become a popular driving force for shape changes, capable of adhering to weight and size constraints and allowing for simplicity in mechanical design. As a step towards creating uncrewed aerial vehicles (UAVs) capable...

An integrated sensing system is presented for flight state awareness of fixed-wing aircraft. The hardware of the system consists of a lightweight and nonobtrusive sensor network that houses a multitude of piezoelectric and strain transducers in a distributed, large areal coverage setting. The sensor network is embedded onto the surface of a model m...

Unlike artificial intelligent systems based on computers, which must be programmed for specific tasks, the human brain can learn in real-time to create new tactics and adapt to complex, unpredictable environments. Computers embedded in artificial intelligent systems can execute arbitrary inference algorithms capable of outperforming humans at speci...

Birds perform astounding aerial maneuvers by actuating their shoulder, elbow, and wrist joints to morph their wing shape. This maneuverability is desirable for similar-sized uncrewed aerial vehicles (UAVs) and can be analyzed through the lens of dynamic flight stability. Quantifying avian dynamic stability is challenging as it is dictated by aerody...

The emergence of the use of mechanical metamaterials for vibration suppression and the creation of frequency gaps in structures requires an understanding of the fundament underlying dynamics partial differential equations coupled to ordinary differential equations. Essentially periodic structures consist of a distributed parameter structure connect...

Some bird species exhibit a flight behavior known as whiffling, in which the bird flies upside-down during landing, predator evasion, or courtship displays. Flying inverted causes the flight feathers to twist, creating gaps in the wing’s trailing edge. It has been suggested that these gaps decrease lift at a potentially lower energy cost, enabling...

The impressive maneuverability demonstrated by birds has so far eluded comparably sized uncrewed aerial vehicles (UAVs). Modern studies have shown that birds' ability to change the shape of their wings and tail in flight, known as morphing, allows birds to actively control their longitudinal and lateral flight characteristics. These advances in our...

Birds morph their wing shape to accomplish extraordinary manoeuvres 1–4 , which are governed by avian-specific equations of motion. Solving these equations requires information about a bird’s aerodynamic and inertial characteristics ⁵ . Avian flight research to date has focused on resolving aerodynamic features, whereas inertial properties includin...

Detecting incipient damage in structures is an important challenge for the engineering community. The design of structural health monitoring (SHM) systems usually involves selection of actuators and sensors, defining their positions on the structure and post-processing output signals. Another important task is to define the characteristics of the e...

Forpractical considerations reinforcement learning has proven to be a difficult task outside of simulation when applied to a physical experiment. Here we derive an optional approach to model free reinforcement learning, achieved entirely online, through careful experimental design and algorithmic decision making. We design a reinforcement learning...

Acoustic Black Hole (ABH) structures allowing for wave manipulation and energy focalization have potential applications in broadband structural vibration suppression. In this work, the vibration transmission characteristics of a plate strip embedded with multiple two-dimensional (2D) ABH without additional damping material were investigated. Both t...

SICB presentation about the now published work: https://www.nature.com/articles/s41586-022-04477-8

View Video Presentation: https://doi.org/10.2514/6.2022-1473.vid We present an integrated sensing system for flight state awareness of fixed-wing aircraft. Hardware of our system consists of a lightweight and non-obtrusive sensor network that houses a multitude of piezoelectric and strain transducers in a distributed, large areal coverage setting....

Detecting incipient damage in structures is an important challenge for the engineering community. The design of structural health monitoring (SHM) systems usually involves selection of actuators and sensors, defining their positions on the structure and post-processing output signals. This article presents an approach to determine the optimal frequ...

Monitoring the structural performance of engineering structures has always been pertinent for maintaining structural health and assessing the life cycle of structures. Structural Health Monitoring (SHM) and Structural Damage Detection (SDD) fields have been topics of ongoing research over the years to explore and verify different monitoring techniq...

Limited by the structure, the high-efficiency vibration energy harvesting and vibration suppression have always been a theoretical bottleneck and technical challenge in this field. The nonlinear design of the new vibration structure is an indispensable link in the development of vibration energy harvesting and vibration suppression technologies. No...

The continuous monitoring of strain in fiber-reinforced composites while in service typically requires bonding a network of sensors to the surface of the composite structure. To eliminate such needs, and to reduce bulk and limit additional weight, this work utilizes the transfer printing of laser induced graphene (LIG) strain gauges onto the surfac...

Structural health monitoring of fiber reinforced composites is an extensive field of research that aims to reduce maintenance costs through in-situ damage detection. However, the need for externally bonded sensor systems and complicated fabrication processes limit the widespread application of most current structural health monitoring techniques. T...

Birds dynamically adapt to disparate flight behaviours and unpredictable environments by actively manipulating their skeletal joints to change their wing shape. This in-flight adaptability has inspired many unmanned aerial vehicle (UAV) wings, which predominately morph within a single geometric plane. By contrast, avian joint-driven wing morphing p...

Unlike artificial intelligent systems based on computers which have to be programmed for specific tasks, the human brain “self‐programs” in real time to create new tactics and adapt to arbitrary environments. Computers embedded in artificial intelligent systems execute arbitrary signal‐processing algorithms to outperform humans at specific tasks, b...

Here, we reviewed published aerodynamic efficiencies of gliding birds and similar sized unmanned aerial vehicles (UAVs) motivated by a fundamental question: are gliding birds more efficient than comparable UAVs? Despite a multitude of studies that have quantified the aerodynamic efficiency of gliding birds, there is no comprehensive summary of thes...

During the last decade, Convolutional Neural Networks (CNNs) have become the de facto standard for various Computer Vision and Machine Learning operations. CNNs are feed-forward Artificial Neural Networks (ANNs) with alternating convolutional and subsampling layers. Deep 2D CNNs with many hidden layers and millions of parameters have the ability to...

Fiberglass-reinforced composite materials are commonly used in engineering structures subjected to dynamic loading, such as wind turbine blades, automobiles, and aircraft, where they experience a wide range of unpredictable operating conditions. The ability to monitor these structures while in operation and predict their remaining structural life w...

Current in situ piezoresistive damage detection techniques for fiberglass-reinforced composites are limited in widespread application as they require complex processing techniques which inhibit the scalability of the methods. To eradicate such challenges and expand the use of piezoresistive monitoring of fiberglass composites, this work utilizes a...

Temperature effects are predominantly ignored when computing the dynamic response of structures. Yet, in applications where large changes in temperature occur, the dynamic response can drastically change. This is particularly true for polymers. While the temperature effects on modulus and loss factor are often available for most polymers, this chan...

Monitoring structural damage is extremely important for sustaining and preserving the service life of civil structures. While successful monitoring provides resolute and staunch information on the health, serviceability, integrity and safety of structures; maintaining continuous performance of a structure depends highly on monitoring the occurrence...

An investigation of lateral effects experienced by a rigid gull wing shapes. Oral presentation only. Details will be published in future work.

In situ monitoring of strain and damage in fiber-reinforced composites provides critical information regarding the state of the material without requiring the structure to be removed from operation. In order to avoid the use of complex, heavy, and bulky sensor networks to track the state of the structure, recent focus has turned to multifunctional...

Recent work concerned with passive vibration suppression in structural systems has focused on the development of metastructures. Metastructures (also called architected materials) are a type of mechanical metamaterial: an object arranged or constructed in such a manner that it has traits unachievable by its constituent material. Metastructures ofte...

Train movements generate oscillations that are transmitted as waves through the track support system into its surroundings. The waves reaching nearby structures may cause distractions for humans and/or result in equipment malfunctions. Dynamic characteristics of surrounding media affect the level of vibrations experienced in nearby buildings. In th...

Birds morph their wing shape to adjust to changing environments through muscle-activated morphing of the skeletal structure and passive morphing of the flexible skin and feathers. The role of feather morphing has not been well studied and its impact on aerodynamics is largely unknown. Here we investigate the aero-structural response of a flexible a...

Waste energy harvesting is a method of generating small amounts of energy, usually through vibrations or thermal energy. Macro-fiber Composites (MFCs) have been employed in energy harvesting applications utilizing the piezoelectric effect, however, energy harvesting using the pyroelectric effect in MFCs has not been thoroughly explored. This paper...

Structural health monitoring of fiber-reinforced composite materials is of critical importance due to their use in challenging structural applications where low density is required and the designs typically use a low factor of safety. In order to reduce the need for external sensors to monitor composite structures, recent attention has turned to mu...

Sensors that provide critical information about jet engine performance are widely installed on static components but are rarely found on rotors because of their inaccessibility and extremely high rotation speeds. We present a new monitoring method, integrating energy harvesting technology with wireless sensors to achieve real-time self-powered engi...

Monitoring structural damage is extremely important for sustaining and preserving the service life of civil structures. While successful monitoring provides resolute and staunch information on the health, serviceability, integrity and safety of structures; maintaining continuous performance of a structure depends highly on monitoring the occurrence...

This article presents a novel morphing unit cell concept which relies on the combination of shape memory alloy wires for actuation and permanent magnets to enable multistability. Two distinct applications are investigated experimentally, consisting in a morphing beam metastructure made with three unit cells and a variable camber airfoil metastructu...

Although there have been numerous efforts into harnessing the snap through dynamics of bistable structures with piezoelectric transducers to achieve large energy conversion, these same dynamics are undesirable under morphing applications where stationary control of the structure's configuration is paramount. To suppress cross-well vibrations that p...

Birds morph their wings in gliding flight to dynamically adjust to variable flight conditions. The adaptibility afforded by morphing wings is desirable for future unmanned aerial vehicles (UAVs). Since birds and UAVs fly at a similar Reynolds number, birds are a great source of inspiration for morphing wing design. Birds’ wings are made of a skelet...

The current state-of-the-art for aircraft aerodynamic alleviation or unloading typically uses control surfaces to mitigate unwanted effects and retain stability. However, this requires a series of sensors, controllers, and actuators to monitor and adapt to these changes and as a result, may not warrant an instantaneous response. Here, we use biolog...

Control surfaces such as an elevator, rudder and flaps allow a pilot to effectively control an aircraft’s flight path. In contrast, birds do not have discrete control surfaces, but can morph the shape of their wings to provide flight control. Avian wings morph passively, through the deflection of feathers and skin, or actively, by adjusting skeleta...

This paper presents a method for active vibration control of smart thin cantilever plates. For model formulation needed for controller design and simulations, finite difference technique is used on the cantilever plate response calculations. Piezoelectric patches are used on the plate, for which a neural network based control algorithm is formed an...

The use of self-organizing maps and artificial neural networks for structural health monitoring is presented in this paper. The authors recently developed a nonparametric structural damage detection algorithm for extracting damage indices from the ambient vibration response of a structure. The algorithm is based on self-organizing maps with a multi...

Structural damage detection methods available for structural health monitoring applications are based on data preprocessing, feature extraction, and feature classification. The feature classification task requires considerable computational power which makes the utilization of centralized techniques relatively infeasible for wireless sensor network...

Here, both piezoelectric and non-piezoelectric nanostructures are used within fiber reinforced composites to improve the damping capabilities of the host material. This work investigates and isolates the role of both piezoelectricity and the mechanical redistribution of strain on the damping properties of fiber reinforced composites through the int...

Train movements generate oscillations that are transmitted as waves through the track support system into its surroundings. The vibration waves propagate through the soil layers and reach to nearby buildings creating distractions for human activities and causing equipment malfunctioning. Not only the train components and the rails, but also the sur...

Throughout the history of aviation, birds have provided continued inspiration for aircraft design. This is in part because birds exhibit impressive maneuverability and control when compared to current aircraft. This skill is often attributed to a bird’s ability to dynamically change the shape of their wings, which allows them to modulate performanc...

This paper presents an experimental analysis of the dynamic response of bistable composite laminates that are harmonically excited. Bistable composite laminates are unsymmetric thin laminates that possess two self-equilibrated positions at room temperature. The resonant frequencies of bending under small harmonic excitations have been identified to...

Materials like the Macro-fiber Composite (MFC) are employed in energy harvesting applications utilizing the piezoelectric effect. However, energy harvesting using the pyroelectric effect in MFCs is an unexplored topic. This paper takes strides in understanding the thermal micromechanical interactions that MFCs experience due to this effect and lead...

The Spanwise Morphing Trailing Edge (SMTE) concept seeks to improve aerodynamic performance for small UAVs by creating a smooth control surface that can achieve complex spanwise variation in camber while eliminating gaps and discontinuities. This work represents the first force and deformation analysis of a morphing wing with a smooth surface and i...

During the last decade, Convolutional Neural Networks (CNNs) have become the de facto standard for various Computer Vision and Machine Learning operations. CNNs are feed-forward Artificial Neural Networks (ANNs) with alternating convolutional and subsampling layers. Deep 2D CNNs with many hidden layers and millions of parameters have the ability to...

An experimental study of the single-well and twin-well, also referred to as intra-well and inter-well, respectively, nonlinear dynamics of a bistable composite laminate is presented. An asymmetric four-ply [0/90/0/90] carbon fiber laminate with two cylindrical stable equilibria supported at its center and free at all boundaries is used for the expe...