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== Abstract ==
 
== Abstract ==
  
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<p>Metallized polypropylene film capacitors (MFCs) undergo dielectric aging under thermal stress, critically affecting operational reliability. To address the insufficient sensitivity of traditional loss-detection methods for early warning, this paper employs frequency-domain dielectric spectroscopy (FDS) to conduct accelerated aging tests on 100 &mu;F automotive-grade MFCs at 120&deg;C. The dielectric loss tangent (tan&delta;) and capacitance were measured over a wide frequency range (50 Hz&ndash;12 kHz). A characteristic frequency of 8100 Hz is identified as an early-warning indicator for thermal aging: while traditional methods detect only 0.7% and 2.5% changes after 360 and 720 h aging respectively, FDS captures 13.68% and 27.5% signal changes at 8100 Hz, reaching 55.5% at capacitor failure (1080 h)&mdash;3&ndash;8 times more sensitive than conventional approaches. Further analysis reveals frequency-dependent degradation patterns: the low-frequency band reflects increased conductive loss from electrode corrosion, the mid-frequency band shows the most sensitive relaxation loss changes, while high-frequency changes are slower, collectively reflecting progressive aging from interface to bulk. A health index (HI) model integrating multiple spectral features is developed using an improved weighted fusion algorithm, enabling aging state classification into four levels and remaining lifetime prediction with error within 5.6%. This FDSbased tan&delta; spectral analysis provides a novel approach for MFC lifetime prediction and early aging warning, offering practical significance for enhancing electric drive system reliability in new energy vehicles.OPEN ACCESS Received: 23/10/2025 Accepted: 19/12/2025 Published: 21/09/2026</p>
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<p>As global conventional oil and gas resources continue to deplete, exploration and development are increasingly targeting deep and ultra-deep
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reservoirs with high-temperature, high-pressure (HPHT) conditions.This
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paper presents a comprehensive numerical investigation based on a nonlinear finite element model that integrates impact–contact–fluid coupling. The computational framework employs the Cowper–Symonds ratedependent constitutive law, calibrated via Split Hopkinson Pressure Bar
 +
tests, and an Arbitrary Lagrangian–Eulerian (ALE) multiphysics algorithm to handle large-deformation fluid–structure interaction. A systematic parametric study is conducted to quantify the sensitivity of six
 +
key design parameters—tubing length, wall thickness, Young’s modulus,
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yield strength, load amplitude, and internal pressure—on the buckling
 +
response. The numerical results establish a clear sensitivity hierarchy: load
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amplitude > internal pressure > wall thickness > yield strength > length
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> Young’s modulus. The study further elucidates the underlying mechanisms of stress-wave propagation, energy dissipation, and buckling-mode
 +
evolution through a detailed analysis of simulation outputs. An integrated
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energy–stiffness–pressure mitigation strategy is proposed based on the
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numerical findings. This work demonstrates the capability of advanced
 +
computational modeling to provide both mechanistic understanding and
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practical design guidance for deep-well tubular systems, highlighting the
 +
value of numerical methods in addressing complex engineering challenges
 +
where experimental data are limited.</p>
  
 
== Document ==
 
== Document ==
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<pdf>Media:Draft_content_166032187-3835-document.pdf</pdf>
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<pdf>Media:Review_186758166598_6857_154. TSP_RIMNI_82948.pdf</pdf>

Latest revision as of 13:03, 25 September 2026

Abstract

As global conventional oil and gas resources continue to deplete, exploration and development are increasingly targeting deep and ultra-deep reservoirs with high-temperature, high-pressure (HPHT) conditions.This paper presents a comprehensive numerical investigation based on a nonlinear finite element model that integrates impact–contact–fluid coupling. The computational framework employs the Cowper–Symonds ratedependent constitutive law, calibrated via Split Hopkinson Pressure Bar tests, and an Arbitrary Lagrangian–Eulerian (ALE) multiphysics algorithm to handle large-deformation fluid–structure interaction. A systematic parametric study is conducted to quantify the sensitivity of six key design parameters—tubing length, wall thickness, Young’s modulus, yield strength, load amplitude, and internal pressure—on the buckling response. The numerical results establish a clear sensitivity hierarchy: load amplitude > internal pressure > wall thickness > yield strength > length > Young’s modulus. The study further elucidates the underlying mechanisms of stress-wave propagation, energy dissipation, and buckling-mode evolution through a detailed analysis of simulation outputs. An integrated energy–stiffness–pressure mitigation strategy is proposed based on the numerical findings. This work demonstrates the capability of advanced computational modeling to provide both mechanistic understanding and practical design guidance for deep-well tubular systems, highlighting the value of numerical methods in addressing complex engineering challenges where experimental data are limited.

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Document information

Published on 21/09/26
Accepted on 03/07/26
Submitted on 26/03/26

Volume 42, Issue 6, 2026
DOI: 10.23967/j.rimni.2026.10.82948
Licence: CC BY-NC-SA license

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