https://northumbria-test.eprints-hosting.org/id/document/271378

The effects of tyre material and structure properties on relaxation length using finite element method

Tire safety is a pretty important performance for the vehicle. To overcome some disadvantages of the conventional pneumatic tire, a new non-pneumatic mechanical elastic wheel (ME-Wheel) is developed, and the camber performance of ME-Wheel is studied with numerical and experimental methods. A nonlinear three-dimensional finite element model of the ME-Wheel, which includes material nonlinearities, large deformation and the anisotropy of rubber–cord composites, is established. The rubber components of the ME-Wheel are analyzed by Moony–Rivlin model. With a vertical test rig, static loading tests are performed to validate the accuracy and reliability of the finite element model. Experiments and simulations under the static and rolling conditions are conducted to study the influence of different camber angles on the vertical stiffness, wheel deformation, contact pressure distribution and wheel force at the interface. The simulation results and the test results are compared and discussed in detail. The results show that the proposed method is useful for the investigation of mechanical characteristics of ME-Wheel and the later optimal design.

Numerical and experimental investigation on the camber performance of a non-pneumatic mechanical elastic wheel

Constitutive modelling of rubbers: Mullins effect, residual strain, time-temperature dependence

The rubber solid tire was built using three different compound layers. In order to develop solid tire, the finite element method (FEM) was employed to model and analyze its performance. The constitutive model was important to describe the simulated results of FEM; therefore, the hyperelastic material models were implemented for each compound of solid tire layers. The second order Ogden model was the most agreement with the compression test of the rubber compound specimens. The R2 of internal, middle and tread compound layer was 0.990, 0.988 and 0.989, respectively. The solid tire model was developed and tested with the compressive loads. Particularly, the compressive loads on the solid tire were performed with the experiment regarding to the simulation. The solid tire model which was complied with the Ogden model had good agreements with the experimental results. It had an average error less than 8.49%. The Ogden model which was implemented with the mechanical property of rubber compound of solid tire was found that it would be advantageous to design and develop the novel solid tire in the future work.

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A Suitable Constitutive Model for Solid Tire Analysis under Quasi-Static Loads using Finite Element Method

A combination of Finite Element Method (FEM) and Experiment Modal Analysis (EMA) have been employed here to characterize the structural dynamic response of mechanical elastic wheel (ME-Wheel) operating under a specific thermal environment. The influence of high thermal condition on the structural dynamic response of ME-Wheel is investigated. The obtained results indicate that the EMA results are in accordance with those obtained using the proposed Finite Element (FE) model, indicting the high reliability of this FE model applied in analyzing the modal of ME-Wheel working under practical thermal environment. It demonstrates that the structural dynamic response of ME-Wheel operating under a specific thermal condition can be predicted and evaluated using the proposed analysis method, which is beneficial for the dynamic optimization design of the wheel structure to avoid tire temperature related vibration failure and improve safety of tire.

Thermal modal analysis of novel non-pneumatic mechanical elastic wheel based on FEM and EMA

Determination of rolling tyre modal parameters using Finite Element techniques and Operational Modal Analysis

Viscoelastic properties of natural rubber with fatigue damage

Traditionally damage has been studied based on the Stored Energy approach by including an internal variable or independently to predict failure life as epitomised by Miner's rule. However, relating the property changes in rubber to fatigue life remains an open question. Hence, a systematic experimental procedure was implemented to study the fatigue-induced property variation in natural rubber compounds. The experiments were aimed at understanding damage induced mechanical property variations, and to explore whether they can be used for damage evolution law. As per the evolution law used in continuum damage mechanics, the constitutive equation includes an internal variable, which alters the stress-strain relationship. The experimental results do not indicate a monotonous decay of stiffness with fatigue life. Partial recovery of stiffness was observed at intermediate stages of fatigue life - a phenomenon that continuum damage mechanics cannot capture. When a failure based damage law was used to depict hyperelastic behaviour through finite element analysis, the simulation results were not in consonance with the experimental results. On the other hand, the variation in elongation at break and strain energy density at break demonstrated a unique correlation to the cyclic strain and fraction of life consumed. Unlike the conventional perception of damage strain energy arising from stored energy available for deformation, it is asserted that the damage accumulates at the cost of ultimate properties.

Damage evolution in natural rubber: An experimental study

Introduction
Indomethacin, a non-steroidal anti-inflammatory drug (NSAID), has been presented as a broad-spectrum antiviral agent. This randomised clinical trial in a hospital setting evaluated the efficacy and safety of this drug in RT-PCR-positive coronavirus disease 2019 (COVID-19) patients.
Materials & Methods
A total of 210 RT-PCR-positive COVID-19 patients, who provided consent were allotted, to control or case arm, based on block randomisation. The control arm received standard of care comprising paracetamol, ivermectin, and other adjuvant therapies. The patient in the case arm received indomethacin instead of paracetamol, with other medications retained. The primary endpoint was the development of hypoxia/desaturation with SpO2≤93, while time to become afebrile and time for cough and myalgia resolution were the secondary endpoints.
Results
The results of 210 patients were available, with 102 and 108 patients in the indomethacin and paracetamol arms, respectively. We monitored patient profiles along with everyday clinical parameters. Blood chemistry at the time of admission and discharge was assessed.
As no one in either of the arms required high-flow oxygen, desaturation with SpO2 level of 93 and below was an important goal. In the indomethacin group, none of the 102 patients developed desaturation. On the other hand, 20 of the 108 patients in the paracetamol arm developed desaturation. Patients who received indomethacin also experienced more rapid symptomatic relief than those in the paracetamol arm, with most symptoms disappearing in half the time. 56 patients out of 108 in the paracetamol arm had fever on the seventh day, while no patient in the indomethacin group had fever. Either arm did not report any adverse event. The fourteenth-day follow-up revealed that the paracetamol arm patients had faced several discomforts, including myalgia, joint pain, and tiredness; indomethacin arm patients mostly complained only of tiredness. 
Conclusion
Indomethacin is a safe and effective drug for treating patients with mild and moderate Covid-19.

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Krishna Kumar Ramarathnam

Papers

Determination of rolling tyre modal parameters using Finite Element techniques and Operational Modal Analysis

Viscoelastic properties of natural rubber with fatigue damage

Damage evolution in natural rubber: An experimental study

Use of Indomethacin for mild and moderate Covid -19 patients. A Randomized Control Trial

Development of a Scaled Prototype of a Single Unit Heavy Commercial Road Vehicle for Detection of Untripped Rollover