Diagnostics of Polymer Composite Materials by Waveguide Method

This article considers the use of radio wave method for testing polymer composites used as structural material for manufacture of aircrafts. Measuring process, analysis and calculation by integral equation method are described.

Оn the experiment validity of the continuous medium motion detection by the waveguide method

Present work is devoted to the problem of validity increasing of an experiment to detect the motion of a continuous medium by the waveguide method. The study attempts to optimize the experiment to find the optimal scheme for its installation. The target effect, the magnitude of which should be maximum, is the generalized reflection coefficient, which is influenced by both the Fresnel electromagnetic drag coefficient and the polarization plane rotation due to motion of the medium. The main optimization task is to determine the output parameters for the experiment for stable and reliable motion detection of a continuous medium in a waveguide. In this work, a heuristic analysis algorithm is used. Optimization factors: frequency of the signal at microwave, physical dimensions of objects, shape of the waveguide cross-section, linear velocity of the medium. ECAD PathWave EM Design (EMPro) 2021 was used to the experiment designing stages. Distilled water is the moving medium, which is not subject to optimization. The motion of a continuous medium is considered through its refined refractive index. The maximum magnitude of the target effect is observed for the topology with a rectangular waveguide and with a tube oriented along a wide wall at f = [9.3 ÷ 9.5] GHz. These values coincide with a good degree of accuracy with the already conducted experiments.

Artificial Reflector for Setting up a Flaw Detector that Implements an Acoustic Waveguide Method for Monitoring Composite Reinforcement

Предложен способ нанесения искусственного отражателя на длинномерный объект без разрушения его тела, что позволяет разработать настроечный образец для волноводного метода контроля при упрощении способа нанесения искусственного отражателя. На основании существующих методик оценки спектральных свойств сигналов, отраженных и прошедших через участки с перепадом сечения, разработана расчетная модель. Модель позволяет оценить амплитуды эхосигналов в зависимости от высоты и длины искусственного отражателя. Приведены результаты моделирования и экспериментальных исследований влияния габаритных размеров искусственного отражателя на эхосигнал. Показано, что максимум эхосигнала достигается при длине искусственного отражателя на 19 % меньше значения, соответствующего критерию четверти волнового резонанса. Амплитуда от искусственного отражателя в 1,2…1,3 раза меньше процента прироста площади, и с увеличением площади в зоне отражателя различия растут в силу уменьшения коэффициента его прозрачности.Полученные зависимости позволяют по амплитуде эхосигнала и видимой длине дефекта оценить его внутренний размер. Предлагаемая методика характеризуется высокой точностью, оперативностью и позволяет повысить достоверность волноводного метода контроля длинномерных объектов из полимерных композитных материалов (пруток, труба, арматура).

A 2D Waveguide Method for Lithography Simulation of Thick SU-8 Photoresist

Due to the increasing complexity of microelectromechanical system (MEMS) devices, the accuracy and precision of two-dimensional microstructures of SU-8 negative thick photoresist have drawn more attention with the rapid development of UV lithography technology. This paper presents a high-precision lithography simulation model for thick SU-8 photoresist based on waveguide method to calculate light intensity in the photoresist and predict the profiles of developed SU-8 structures in two dimension. This method is based on rigorous electromagnetic field theory. The parameters that have significant influence on profile quality were studied. Using this model, the light intensity distribution was calculated, and the final resist morphology corresponding to the simulation results was examined. A series of simulations and experiments were conducted to verify the validity of the model. The simulation results were found to be in good agreement with the experimental results, and the simulation system demonstrated high accuracy and efficiency, with complex cases being efficiently handled.

Determination of dielectric permeability of substances by electromagnetic waveguide method

A method for determining the complex permittivity of substances by the electromagnetic (EM) waveguide method in the microwave range using electrodynamics and the theory of multilayer dielectric structures is considered. The expression for the complex reflection coefficient of an EM wave in a waveguide with a substance sample is studied. Calculations of the dielectric constant of substances are carried out by analytical and numerical methods using computers. To obtain the desired complex permittivity of a substance, we use the relationship between the expression for the reflection coefficient modulus and the value of the standing wave coefficient over voltage measured in advance in the frequency range. The method is suitable for automation and application in enterprises producing and using fuels, construction and agricultural products. From the found value of the dielectric constant, the quality of substances can be determined. For example, the results of determining the dielectric constant several coals and solid-state foam are given.