Innovative Mechanical Engineering

NUMERICAL ASSESSMENT OF STRUCTURAL INTEGRITY AND FATIGUE LIFE OF AUTOMOTIVE LPG TANK AND MOUNTING COMPONENTS UNDER REGULATORY LOADING CONDITIONS

Miroslav Mijajlović — 2026-02-10

A nonlinear finite element model was formulated to assess the structural integrity and fatigue life of an automotive LPG tank assembly comprising the cylindrical pressure vessel, clamping straps, holders, and telescopic supports. Experimentally characterized material properties and realistic frictional contacts were incorporated, while fluid–structure effects were approximated via mass–spring surrogates for sloshing and internal pressure. The assessment covered static and quasi‑static scenarios (bolt pretensioning, tank filling) and dynamic conditions consistent with regulatory impacts of 8g lateral and 20g longitudinal accelerations. Vibrodynamic fatigue evaluation employed a Power Spectral Density methodology based on Welch’s estimator to predict life under stochastic vehicle‑induced excitation. Results indicate no catastrophic failure across loading regimes; however, mounting straps exhibit pronounced plasticity during tightening and accumulate ~91% fatigue damage at ten years, aligning with mandated replacement intervals. The pressure vessel shows negligible fatigue degradation and an unrealistically extended predicted life, motivating future work that incorporates cyclic filling/emptying through transient drive–idle–refuel sequences and derived load spectra. The methodology provides a rigorous computational basis for durability assessment and compliance verification of LPG tank installations while reducing reliance on extensive physical testing.

DESIGN AND FABRICATION OF A BATTERY-POWERED TRICYCLE FOR SUSTAINABLE URBAN TRANSPORT IN SUB SAHARAN AFRICA

Stanley U. Idi — 2026-06-03

Rapid urbanization in Sub-Saharan Africa (SSA) has intensified pressure on existing transport systems, exposing persistent challenges related to accessibility, safety, affordability, and environmental sustainability. Informal mobility modes such as motorcycles and internal combustion engine (ICE) tricycles have expanded rapidly to meet transport demand, but they are associated with high emissions, noise pollution, safety risks, and increasing operational costs. In response to these challenges, this study presents the design, fabrication, analytical evaluation, and experimental testing of a battery-powered electric tricycle developed specifically for urban transport conditions in SSA.A structured engineering design methodology was adopted, encompassing material selection, component fabrication, system assembly, and performance validation. Mild steel was selected as the primary frame material based on a weighted decision matrix considering strength, cost, durability, and manufacturability using locally available fabrication techniques. Analytical design calculations were conducted to estimate power requirements, energy consumption, battery capacity, load distribution, frame bending moments, suspension characteristics, and stability-related parameters. A prototype electric tricycle powered by a 48 V lithium-ion battery and dual 500 W rear hub motors was fabricated and subjected to controlled load, endurance, speed, handling, and braking tests under realistic operating conditions. Experimental results demonstrated that the tricycle safely supported a 100 kg payload without structural deformation, achieved a maximum speed of 60 km/h, and operated continuously for approximately 80 minutes under full-load conditions, exceeding the initial design targets. The findings confirm that the proposed design meets essential performance, safety, and efficiency requirements for short-range urban mobility. This study contributes practical engineering evidence toward the development of affordable, locally manufacturable electric tricycles and supports their potential role in advancing sustainable intermediate transport solutions in Sub-Saharan Africa.

TWO NEW BASIC RHEOLOGICAL DISCRETE DYNAMIC SYSTEMS OF THE FRACTIONAL TYPE OF PIEZOELECTRIC PROPERTY: THE KELVIN-VOIGT-FARADAY OSCILLATOR, AND THE MAXWELL-FARADAY CRAWLERoscillator, and the Maxwell-Faraday crawler

Katica (Stevanovic) Hedrih — 2026-06-03

We introduce two new fundamental rheological elements: a fractional‑type Newtonian viscous element with a fractional‑order differential constitutive relation and inherent energy dissipation, and a Faraday ideally elastic piezoelectric element characterized by electrical polarization induced by mechanical deformation.
Using these elements, two new standard light rheological binder models are formulated: the standard light Kelvin-Voigt-Faraday fractional‑type model and the standard light Maxwell-Faraday fractional-type model. Fractional‑order differential constitutive relations are derived for both models. The former exhibits the property of delayed elasticity, while the latter demonstrates fractional stress relaxation.
Based on these models, two discrete rheological dynamical systems with fractional‑order behavior and piezoelectric properties are defined and their dynamics are investigated. According to their dynamic characteristics, the systems are termed the fractional Kelvin-Voigt-Faraday rheological oscillator and the fractional Maxwell-Faraday rheological crawler.
For the Kelvin-Voigt-Faraday oscillator, Laplace transforms and approximate analytical expressions for free and forced fractional‑order oscillatory modes with piezoelectric coupling are obtained. For the Maxwell-Faraday crawler, Laplace transforms the independent generalized coordinates-one external and two internal-are derived. The analytical results are illustrated by appropriate graphical representations. Two theorems are formulated and proved.
In the concluding remarks, several analogies between fractional‑type rheological mechanical systems and rheological electrical dynamical systems with piezoelectric properties are presented.

APPLICATION OF LOGISTIC REGRESSION WITH HOG FEATURES FOR GEOMETRIC SHAPE CLASSIFICATION

Aleksandar Petrović — 2026-06-03

This paper investigates the application of Histogram of Oriented Gradients (HOG) features, simple colour statistics, Principal Component Analysis (PCA), and Logistic Regression for the classification of simple geometric shapes, namely circles, squares, and triangles. The work is positioned as a controlled baseline study aimed at evaluating the suitability of lightweight feature-based classification methods for future railway signal recognition pipelines.
The main experiments were conducted on a balanced synthetic dataset containing 4500 images in total, with 1500 samples per class. A leakage-free evaluation protocol was applied by dividing the dataset into training, validation, and test subsets. Hyperparameters were selected exclusively on the validation subset, while final performance was evaluated once on a previously unseen test subset.
The best-performing configuration was obtained using a 128×128 input resolution, 12 HOG orientations, 8×8 pixels per cell, 2×2 cells per block, and 300 PCA components. This configuration achieved a validation accuracy of 0.8028 and a final test accuracy of 0.7978. The results show that increasing the image resolution from 64×64 to 128×128, together with combining HOG descriptors with colour-based features, improves classification performance, while further increasing the resolution to 200×200 does not provide additional benefits.
An additional verification experiment on 30,000 images confirmed the stability of the selected configuration, achieving a test accuracy of 0.8070. The study also discusses how such lightweight classifiers may be used as auxiliary verification modules in future railway signal detection systems.