29 results found
Ghajari M, Hellyer PJ, Sharp DJ, 2017, Computational modelling of traumatic brain injury predicts the location of chronic traumatic encephalopathy pathology, BRAIN, Vol: 140, Pages: 333-343, ISSN: 0006-8950
Khosroshahi SF, Galvanetto U, Ghajari M, 2017, Optimization of the Chin Bar of a Composite-Shell Helmet to Mitigate the Upper Neck Force, APPLIED COMPOSITE MATERIALS, Vol: 24, Pages: 931-944, ISSN: 0929-189X
Wang H, Kow J, Raske N, et al., 2017, Robust and high-performance soft inductive tactile sensors based on the Eddy-current effect, Sensors and Actuators A: Physical, Vol: 271, Pages: 44-52, ISSN: 0924-4247
Tactile sensors are essential for robotic systems to interact safely and effectively with the external world, they also play a vital role in some smart healthcare systems. Despite advances in areas including materials/composites, electronics and fabrication techniques, it remains challenging to develop low cost, high performance, durable, robust, soft tactile sensors for real-world applications. This paper presents the first Soft Inductive Tactile Sensor (SITS) which exploits an inductance-transducer mechanism based on the eddy-current effect. SITSs measure the inductance variation caused by changes in AC magnetic field coupling between coils and conductive films. Design methodologies for SITSs are discussed by drawing on the underlying physics and computational models, which are used to develop a range of SITS prototypes. An exemplar prototype achieves a state-of-the-art resolution of 0.82 mN with a measurement range over 15 N. Further tests demonstrate that SITSs have low hysteresis, good repeatability, wide bandwidth, and an ability to operate in harsh environments. Moreover, they can be readily fabricated in a durable form and their design is inherently extensible as highlighted by a 4 × 4 SITS array prototype. These outcomes show the potential of SITS systems to further advance tactile sensing solutions for integration into demanding real-world applications.
de Boer G, Raske N, Wang H, et al., 2017, Design Optimisation of a Magnetic Field Based Soft Tactile Sensor, SENSORS, Vol: 17, ISSN: 1424-8220
Wang H, de Boer G, Kow J, et al., 2016, Design Methodology for Magnetic Field-Based Soft Tri-Axis Tactile Sensors, SENSORS, Vol: 16, ISSN: 1424-8220
Wang H, de Boer G, Kow J, et al., 2016, A Low-cost Soft Tactile Sensing Array using 3D Hall Sensors, PROCEEDINGS OF THE 30TH ANNIVERSARY EUROSENSORS CONFERENCE - EUROSENSORS 2016, Vol: 168, Pages: 650-653, ISSN: 1877-7058
de Boer G, Wang H, Ghajari M, et al., 2016, Force and Topography Reconstruction Using GP and MOR for the TACTIP Soft Sensor System, 17th Annual Conference on Towards Autonomous Robotic Systems (TAROS), Publisher: SPRINGER INT PUBLISHING AG, Pages: 65-74, ISSN: 0302-9743
Sharif-Khodaei Z, Ghajari M, Aliabadi MH, 2015, Impact Damage Detection in Composite Plates using a Self-diagnostic Electro-Mechanical Impedance-based Structural Health Monitoring System, JOURNAL OF MULTISCALE MODELING, Vol: 6, ISSN: 1756-9737
Ghajari M, Iannucci L, Curtis P, 2014, A peridynamic material model for the analysis of dynamic crack propagation in orthotropic media, COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, Vol: 276, Pages: 431-452, ISSN: 0045-7825
Psarras S, Ghajari M, Robinson P, et al., 2014, Performance of composite plates after multi-site impacts
Sequential multi-site low velocity impacts (LVI) were performed on CFRP composite plates with different thicknesses and the compression after impact (CAI) behaviour was then investigated. A modified CAI rig was designed and manufactured for testing thin composites. A Finite Element (FE) model of the laminate was developed using continuum shell elements. Layers of cohesive elements were inserted between sublaminates in order to model delamination initiation and growth during impacts. An energy-based damage model, developed at Imperial College and implemented into the Abaqus FE system as a user material subroutine, was employed to represent translaminar damage. Finally, the experimentally observed behaviour of the impacted specimens and the accuracy of the FE predictions are discussed.
Thiene M, Ghajari M, Galvanetto U, et al., 2014, Effects of the transfer function evaluation on the impact force reconstruction with application to composite panels, COMPOSITE STRUCTURES, Vol: 114, Pages: 1-9, ISSN: 0263-8223
Childs PRN, Bull AMJ, Ghajari M, 2013, Helmet Performance and Design, Publisher: DEG, ISBN: 978-0-9572298-3-9
Ghajari M, Caserta GD, Galvanetto U, 2013, The Impact Attenuation Test of Motorcycle Helmet Standards, First International Conference on Helmet Performance and Design
Ghajari M, Khodaei ZS, Aliabadi MH, 2013, Impact Identification in Composite Stiffened Panels, 11th International Conference on Fracture and Damage Mechanics, Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 565-568, ISSN: 1013-9826
Ghajari M, Peldschus S, Galvanetto U, et al., 2013, Effects of the presence of the body in helmet oblique impacts, ACCIDENT ANALYSIS AND PREVENTION, Vol: 50, Pages: 263-271, ISSN: 0001-4575
Ghajari M, Sharif-Khodaei Z, Aliabadi MH, et al., 2013, Identification of impact force for smart composite stiffened panels, SMART MATERIALS AND STRUCTURES, Vol: 22, ISSN: 0964-1726
Khodaei ZS, Ghajari M, Aliabadi MH, et al., 2013, SMART Platform for Structural Health Monitoring of Sensorised Stiffened Composite Panels, 11th International Conference on Fracture and Damage Mechanics, Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 581-+, ISSN: 1013-9826
Thiene M, Galvanetto U, Ghajari M, et al., 2013, A frequency analysis applied to force identification, Pages: 2193-2198
A continuous monitoring of aeronautical structures is essential to guarantee the safety of both airplanes and passengers. Impacts are one of the most important causes of damage in aeronautical structures. The possibility to reconstruct the energy and the force history of an impact on a structure can be a useful technique to determine if possible damage is present. In this paper a frequency domain method is applied to a composite plate in order to reconstruct the force caused by an impact. In the first step the position of the load is considered known its force history is identified. In the second step the impact is applied at hypothetical unknown position and both its location and force history are identified. Analyses considering the influence of noise are also conducted. The influence of energy of the impact, relative location between impact and sensors, and position of sensors is also investigated. © 2013 Taylor & Francis Group.
Ghajari M, Khodaei ZS, Aliabadi MH, 2012, Impact Detection using Artificial Neural Networks, 10th International Conference on Fracture and Damage Mechanics (FDM 2011), Publisher: TRANS TECH PUBLICATIONS LTD, Pages: 767-770, ISSN: 1013-9826
Sharif-Khodaei Z, Ghajari M, Aliabadi MH, 2012, Determination of impact location on composite stiffened panels, SMART MATERIALS AND STRUCTURES, Vol: 21, ISSN: 0964-1726
Ghajari M, Galvanetto U, Iannucci L, et al., 2011, Influence of the body on the response of the helmeted head during impact, INTERNATIONAL JOURNAL OF CRASHWORTHINESS, Vol: 16, Pages: 285-295, ISSN: 1358-8265
Ghajari M, Galvanetto U, Iannucci L, et al., 2011, Intracranial response in helmet oblique impacts, Pages: 90-94
The purpose of this work was to investigate the influence of the presence of the body in helmet oblique impacts on the tissue level response of the human head. The kinematic field of the head obtained from full-body and detached-head oblique impacts were used to drive a validated Finite Element model of the human head and evaluate predictors of the diffuse axonal injury (Von Mises stress in the brain) and subdural haematoma (internal energy of the Cerebro-Spinal Fluid (CSF)). It was found that the presence of the body considerably influences the intracranial response. To take into account this effect in detached-head impacts, inertial properties of the head were modified. When the head mass was increased, the Von Mises stress in the brain and the internal energy of the CSF decreased for impacts with relatively high tangential velocities. Modifying the head inertia matrix lowered the Von Mises stress in the brain and the internal energy of the CSF. The best correlation between the modified detached-head and full-body impact results was found when both the head mass and its inertia matrix were modified.
Ghajari M, Iannucci L, Robinson P, et al., 2011, Numerical solutions to fracture mechanics problems using the Peridynamic theory, Composite Structures
Ghajari M, Peldschus S, Galvanetto U, et al., 2011, Evaluation of the effective mass of the body for helmet impacts, INTERNATIONAL JOURNAL OF CRASHWORTHINESS, Vol: 16, Pages: 621-631, ISSN: 1358-8265
Ghajari M, Peldschus S, Galvanetto U, et al., 2010, Influence of the body on head rotational acceleration in motorcycle helmet oblique impact tests, Pages: 95-106
The Finite Element (FE) method has been used to study full-scale oblique impacts of a motorcycle helmet. For these impacts, an elaborate FE model of the human body was employed. The results were compared to the results of the same impacts but by using the detached head of the body. It has been found that the presence of the body influences the head rotational acceleration components (up to 40% for the simulated impact configuration). On the basis of the equations of general three-dimensional motion of a rigid body, it is shown that this influence can be taken into account in detached head impact tests through modifying the inertia matrix of the head. For a severe oblique impact, the modified inertia was calculated and applied to the head. The head rotational acceleration components predicted by using the modified detached head were in good agreement with those obtained from fullscale oblique impacts.
Toma M, Njilie FEA, Ghajari M, et al., 2010, ASSESSING MOTORCYCLE CRASH-RELATED HEAD INJURIES USING FINITE ELEMENT SIMULATIONS, INTERNATIONAL JOURNAL OF SIMULATION MODELLING, Vol: 9, Pages: 143-151, ISSN: 1726-4529
Ghajari M, Deck C, Galvanetto U, et al., 2009, Development of numerical models for the investigation of motorcyclists accidents, Ls-Dyna User’s conference
Ghajari M, Galvanetto U, Iannucci L, 2009, Influence of the body on kinematic and tissue level head injury predictors in motorcyclists accidents, IRCOBI
Shakeri M, Beiglou AA, Ghajari M, 2004, Numerical analysis of axisymmetric collapse of cylindrical tubes under axial loading, Computational Structures Technology
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