Ageing simulation of a hydraulic engine mount: a data informed finite element approach

Hydraulic engine mounts are key elements in an automotive vehicle suspension system that typically experience a change of their designed function during their working lifetime due to progressive material ageing, primarily from the elastomeric component. Ageing of the engine mount, resulting from severe and continuous mechanical and thermal loads, can have a detrimental impact on the ride and comfort and long-term customer satisfaction. This paper introduces a new practical methodology for simulating the ageing behaviour of engine mounts resulting from the change in properties of their elastomeric main spring component. To achieve this, a set of dynamic mechanical thermal analysis tests were conducted on elastomeric coupons taken from a set of engine mounts with different service and ageing conditions. These experimental results were used to characterise the change in mechanical response of the elastomer and to build up an empirical elastomer ageing model. Then a finite element model of the main spring was developed that used the elastomer ageing model so that the ageing behaviour of the engine mount could be simulated. The resulting ageing model was verified by using experimental results from a second batch of ex-service engine mounts. The results show an increasing trend of the vertical static stiffness of the engine mounts with distance travelled (or age) up to a certain distance (approximately 95,000 km). The trend is then reversed and a softening effect is observed. Moreover, the results reveal that both the maximum stiffness value and the distance travelled at the peak stiffness decrease as the temperature increases

Analysis of Cantilever Triple-Layer Piezoelectric Harvester (CTLPH): Non-Resonance Applications

In this research, a design guideline for a kinetic energy converter using a cantilever tri-ple-layer piezoelectric harvester (CTLPH) for low-frequency applications is presented. By combin-ing the constitutive and internal energy equations, the analytical equations for harvested voltage and power were developed. It was also found that frequency of motion, applied tip force, piezoe-lectric coefficients, geometrical dimensions, and mechanical properties of layers play significant roles in the performance of the harvester. Having characterised the voltage regulator module, LTC3588, the dependency of output voltage on both the storage and output capacitors of the LTC3588 was investigated. An experimental measurement using the optical method was carried out to determine the applied tip force. Furthermore, the performance of the CTLPH in low frequencies (< 3.3 Hz) for various resistive loads was investigated. It was found that both excitation frequency and external resistance load are effective on the maximum generated power. The developed CTLPH shows the optimum power of 17.3

Nutritional Aspects of Treatment in Epileptic Patients

How to Cite This Article: Soltani D, Ghaffar pour M, Tafakhori A, Sarraf P, Bitarafan S. Nutritional Aspects of Treatment in Epileptic Patients. Iran J Child Neurol. Summer 2016; 10(3): 1-12. Abstract Epilepsy is a neurological disorder characterized by interruption of normal neuronal functions that is manifested by behavioral disorders, changing of awareness level, and presence of some sensory, autonomic and motor symptoms or signs. It is resulted from many different causes. Many antiepileptic drugs (AEDs) are considered to manage epileptic attacks. Some of them  hange metabolism and absorption of many nutrients. Therefore, epileptic patients may be in higher risk of nutrient deficiency and its unwelcome effects. In the present paper, we intend to review the relationship between nutrition and epilepsy in two aspects. In one aspect we discuss the nutritional status in epileptic patients, the causes of nutritional deficiencies and the way of compensation of the nutrient deficiencies. It will guide these patients to have a healthy life. In another aspect we explain the role of some nutrients and specific diets in management of epileptic attacks. It can help to better control of epileptic attacks in these patients. References1. Gragnani A, Müller BR, Oliveira AF, Ferreira LM. Burns and epilepsy–review and case report. Burns 2014;41:e15–e18.2. Carlson C, Dugan P, Kirsch HE, Friedman D, Investigators E. Sex differences in seizure types and symptoms.EpilepsyBehav 2014; 41:103-8.3. Speed D, O’Brien TJ, Palotie A, Shkura K, Marson AG, Balding DJ, et al. Describing the genetic architecture of epilepsy through heritability analysis. Brain 2014; 137:2680-9.4. Poduri A, Sheidley BR, Shostak S, Ottman R. Genetic testing in the epilepsies developments and dilemmas. Nat Rev Neurol 2014; 10:293-9.5. Malkan A, Beran RG. An appraisal of the new operational definition of epilepsy-Then and now. Epilepsy Behav 2014; 41:217-20.6. Wong VC, Fung C, Kwong AK. 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Bochyńska A, Lipczyńska-Łojkowska W, Gugała-Iwaniuk M, Lechowicz W, Restel M, Graban A, et al. The effect of vitamin B supplementation on homocysteine metabolism and clinical state of patients withchronic epilepsy treated with carbamazepine and valproic acid. Seizure 2012; 21:276-81.65. Bailey LB. Folate in health and disease: in: Taylor and Francis group, editor. folate and neurological disease. 2nd ed. CRC Press; 2009; 325-355.66. Paknahad Z, Chitsaz A, Zadeh AH, Sheklabadi E. Effects of common anti-epileptic drugs on the serum levels of homocysteine and folic acid. Int J Prev Med 2012; 3:S186–S190.67. Jeeja MC, Jayakrishnan T, Narayanan PV, Kumar MSV, Thejus T, Anilakumari VP. Folic acid supplementation on homocysteine levels in children taking antiepileptic drugs: A randomized controlled trial. J PharmacolPharmacother 2014; 5:93-99.68. Coburn SP. Location and turnover of vitamin B6 pools and vitamin B6 requirements of Humansa. Ann N Y AcadSci 1990; 585:76–85.69. 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Effects of steps on the load bearing capacity of 3D-printed single lap joints

Damage in adhesively bonded joints typically initiates in the overlap area due to high level of bonding (peel) stress. Different approaches are being considered to decrease the peel stress and improve the overall strength of the joint. One possible approach is to shape the over lap area into a stepped form configuration and enhance the performance of the joint. In the current study, we investigate effects of stepped-shape overlap area on the load bearing capacity of additively manufactured single-lap joints. To this aim, stepped-lap adhesively bonded joints with different designs and geometries in the overlap (bonding) area are considered with 3D-printed polylactic acid (PLA) adherends using the fused deposition modeling (FDM) process. Three configurations with different step sizes are considered to manufactured a set of adhesively bonded single-lap joints and to investigate the optimum length of the steps. The results are compared with our previous experimental findings on 3D-printed conventional single-lap joints. The obtained outcomes reveal that creating steps in the overlap area has a significant influence on the structural integrity and fracture load of 3D-printed adhesive-bonded joints and the bonded structures with identical step size in boding area reveal a better performance in load carrying capacity and shows a higher fracture load. Parallel to the experimental practices, a finite element model also developed to simulate the load carrying performance of the adhesively bonded single-lap joints with equal step size and 3D-printed PLA adherends. The FE model confirms the experimental outcomes and reveals the details of the cohesive failure and damage evolution mechanism in this bonded structures with PLA printed adherends. The proposed technique has a great potential to be a competitive alternative to conventional single-lap joints made by 3D printing. The presented results can be used for further fabrication of 3D-printed joints with a better structural performance

A New Active Anti-Vibration System Using a Magnetostrictive Bimetal Actuator

This paper introduces a new vibration reduction system using a magnetostrictive (Fe-Ga alloy) bimetal actuator. The proposed method (i) uses a magnetostrictive bimetal actuator instead of prevalent single material ones that need an auxiliary temperature control system and (ii) utilises a novel disturbance rejection control scheme that eliminates an unknown disturbance, without needing knowledge of its dynamics. In experiments, the vibration source is demonstrated as an unbalanced motor attached to the tip of a cantilever beam, resembling a beam-like element subject to ambiance vibrations. In the first step, the fundamental of this anti-vibration system is introduced and described. Then, analytical and data-driven modelling for the combination of the beam, the motor, and the bimetal is reported. These follow by model validation and impulse response analysis. Then, the proposed control system is introduced in detail. Experimental results indicate that the control system results in 33.6% decrease in beam vibration amplitude. Furthermore, the presented method in this paper can be employed as a design guideline for future applications

Charge Estimation of Piezoelectric Actuators: A Comparative Study

This article first reviews the position control of piezoelectric actuators, particularly charge-based sensorless control systems, which often include a charge estimator as a key component. The rest of the paper is about charge estimators for piezoelectric actuators. Two of the most recent/effective types of these estimators utilise either a sensing capacitor (type I in this paper) or a sensing resistor (type II); the latter (and the newer) type is broadly known as a digital charge estimator. Some experimental results in the literature show that, with the same loss in excitation voltage, a considerably higher amount of charge can be estimated with a type II estimator in comparison with a type I estimator; therefore, the superiority of type II estimators was acknowledged. In order to re-assess this conclusion, this paper equitably compares type I and II estimators through analytical modelling and experimentation. The results indicate that type II estimators have only a slight advantage in estimating higher amounts of charge, if both type I and II estimators are designed appropriately. At the same time, type II estimators have disadvantages; e.g., the resistance of type II estimators has to be tuned to suit different excitation frequencies. This research concludes that capacitor-based (type I) charge estimators for piezoelectric actuators, with pertinent design and implementation, can be still the prime solution for many charge estimation problems despite claims in the literature in the last decade

Structural integrity of adhesively bonded 3D-printed joints

Fabrication of polymeric components with complex geometry has been increased in the recent years. As additive manufacturing (AM) showed its unique capabilities, it has been widely used in production of geometrically-complex parts. Although various types of bonding have been developed, utilizing adhesive joints is common in different polymeric structures. In the current study, influence of 3D printing parameters and adhesive thickness on the performance of adhesively bonded joints have been studied. To this aim, we have used fused deposition modeling (FDM) process and polylactic acid (PLA) material to fabricate single-lap joints. The specimens are fabricated under different printing conditions to determine influence of printing parameters on the mechanical behavior of the joints. Moreover, adhesive with three different thicknesses was used to investigate effect of adhesive thickness on the structural integrity of the 3D-printed joints. Additionally, a series of finite element analysis was performed and agreement between experimental observation and numerical results has been documented. As FDM process has garnered significant attention, the outcomes of this study can be used for further development