Journal of Science and Transport Technology

Elastic and failure properties of 2D primitive TPMS lattices with varying shape factor

2026-04-02T06:06:07+00:00

Architected materials based on Triply Periodic Minimal Surfaces (TPMS) have demonstrated outstanding mechanical performance; however, their two-dimensional (2D) counterparts remain insufficiently explored. This study presents a comprehensive numerical investigation of the elastic response and failure behavior of 2D Primitive TPMS lattice structures, with particular emphasis on the role of geometric parameters C₁ and C₂. A phase-field damage framework is employed to capture the full mechanical evolution, from initial elastic deformation to crack initiation and subsequent propagation leading to ultimate failure. The results reveal that mechanical performance is governed not only by relative density but also critically by geometric configuration. In particular, structures with nearly identical relative densities can exhibit strength variations of up to five times, underscoring the dominant influence of shape parameters. In addition, certain configurations display pronounced auxetic behavior, with a minimum Poisson’s ratio of −0.12 observed for C₁ = 1.2 and C₂ = 0.8. Failure consistently initiates at the specimen center, where stress concentration is most severe. Overall, this study provides both a high-quality numerical dataset and fundamental insights into the geometry–mechanical performance relationship of 2D TPMS lattices. The findings establish a foundation for the rational design and optimization of TPMS-based architected materials in advanced engineering applications.

Numerical study of punching shear behavior of flat slab with openings

2026-03-25T13:11:05+00:00

Punching shear is a critical failure mode in reinforced concrete flat slabs, particularly when openings are located near slab–column connections, where they disrupt load transfer and intensify stress concentration. This study develops a validated nonlinear finite element model to investigate the punching shear behaviour of flat slabs with openings. The model shows good agreement with experimental results in terms of load–deflection response and failure mode, with discrepancies in ultimate load below 4%. A systematic parametric study is conducted to quantify the effects of opening location, size, and shape. The results show that openings adjacent to the column reduce the ultimate load to 166.7 kN, while increasing the distance to 50 mm and 100 mm enhances capacity by 23.86% and 24.93%, respectively. Increasing opening size leads to strength reductions of up to 12.4%, whereas circular openings exhibit higher capacity than square ones due to reduced stress concentration. The study provides a validated numerical framework and a quantitative assessment of the combined influence of opening geometry and position on punching shear behaviour, offering new insight into the governing failure mechanisms.

Dynamic Response of a Viscoelastic FG Beam under Axial Compression and Moving Harmonic Loads

2026-03-07T08:07:57+00:00

This study investigates dynamic response of a viscoelastic FG beam under axial compression and moving harmonic loads. The Mori–Tanaka model is used to determine the thickness-wise power-law material properties of the beam. The Kelvin–Voigt model is used to represent viscoelastic damping in the beam. General motion equations are established using FEM. A parametric study is performed to investigate the effects of material distribution, damping, convoy velocity, axial compressive force, inter - load spacing, and excitation frequency on the dynamic response. Numerical simulations demonstrate that these parameters have a pronounced effect on the dynamic deflection response of FG beams.

Thermomechanical vibration of sandwich beams with FGP core based on a Timoshenko beam formulation

2026-03-09T10:25:14+00:00

This paper investigates the thermomechanical vibration of sandwich beams with isotropic homogeneous face layers and a core of porous material by using a Timoshenko finite element beam formulation. The material properties of the sandwich beams are dependent on the environmental temperature, and the porosity distribution in the core through the beam thickness follows a cosine function. Applying the finite element method, a beam element formulation is derived and used to construct the discretized motion equation. The present formulation employs the solution of the homogeneous equilibrium equations to approximate the rotation and deflection of the beams, which helps to improve the efficiency and to avoid the shear-locking problem. The finding emphasizes the significant impact of the environmental temperature and the porous parameter on the thermomechanical vibration responses. A detailed investigation is presented to illustrate the effects of the temperature variations, the porous coefficient, the specific beam configuration, and the ratio of span to height of the beam on the vibration of the sandwich beams.

A Meshfree Proportional Topology Optimization of Bi-Directional Functionally Graded Plates Based on Third-Order Shear Deformation Theory

2026-03-15T06:58:15+00:00

This work develops a meshfree topology optimization formulation for plates composed of bidirectional functionally graded materials (2D-FGM). The plate response is described using the third-order shear deformation theory, allowing transverse shear effects to be incorporated without shear correction factors. The radial point interpolation method (RPIM) is adopted to construct the approximation field, thereby reducing the reliance on conventional mesh-based discretization. The spatial variation of material properties in the two in-plane directions is defined through a power-law model. For topology optimization, a proportional topology optimization (PTO) strategy is employed to iteratively redistribute material according to the structural response without requiring sensitivity gradients. Several numerical studies are carried out to assess the performance of the proposed approach. The results indicate that the present formulation can produce stiff and smooth material layouts for 2D-FGM plates. The proposed RPIM-PTO framework therefore provides an effective computational tool for the lightweight design of advanced graded plate structures.

A Three-variable Isogeometric Model for Free Vibration Analysis of Triply Periodic Minimal Surface Plates

2026-03-26T07:46:26+00:00

Triply Periodic Minimal Surface (TPMS) architectures offer an optimal balance of minimal weight and superior mechanical resilience. Consequently, they have emerged as excellent candidates for advanced engineering applications, including aerospace and biomedical structures. To better understand their vibrational behavior, this study presents an effective framework dedicated to the free vibration analysis of TPMS-based plates. The computational model employs isogeometric analysis (IGA) in conjunction with a higher-order plate theory. This approach efficiently reduces the required independent variables to three while automatically satisfying stress-free boundary conditions. The reliability of this numerical approach is first confirmed through benchmark comparisons. Subsequently, the study investigates the vibrational characteristics of plates modeled with Gyroid, Primitive, and I-graph and Wrapped Package-graph (IWP) architectures. A key focus is placed on the impact of architectural variation. Therefore, uniform (Uni.), symmetric (Sym.), and asymmetric (Asym.) porosity distributions along the plate's thickness are systematically analyzed. The computational results indicate a profound sensitivity of the natural frequencies to both the selected porosity distribution functions and the underlying TPMS geometries. Ultimately, these findings demonstrate the critical role of these parameters in optimizing lightweight, high-performance structural designs.

Pseudo-Lower-Bound Limit Analysis of Structures Using an Enhanced Cell-Based Smoothed Finite Element Method

2026-03-11T20:30:41+00:00

Volumetric locking remains a major obstacle in pseudo-lower-bound limit analysis of near-incompressible structures. To overcome this difficulty, a bubble-enriched cell-based smoothed finite element approach is proposed, in which quadrilateral elements are supplemented with internal enrichment and the equilibrium constraints are imposed in a weak, spatially smoothed form over subcells. The resulting discrete problem is recast as a conic optimization model and solved efficiently using second-order cone programming (SOCP) techniques. Numerical examples confirm that the proposed approach effectively suppresses the locking behavior observed in the standard CS-FEM-Q4 formulation under near-incompressible plane-strain conditions. Computed solutions exhibit errors as low as 0.1% relative to analytical and reference results, while large-scale optimization problems can be solved within a few seconds. These results demonstrate that the proposed method provides an accurate, robust, and efficient computational tool for pseudo-lower-bound limit-state analysis, particularly for structures exhibiting near-incompressible behavior.

Reduced isogeometric model for vibration analysis of beams under damping based on a fifth-order generalized shear deformation theory

2026-03-28T13:05:26+00:00

This work aims to use the reduced isogeometric model for analyzing the vibration behavior of beams under damping based on a fifth-order generalized shear deformation theory (GSDT). This beam theory utilizes the fifth-order polynomial function to represent the displacements through the beam height. Whilst the isogeometric analysis (IGA) employs B-spline functions to approximate the displacements along the beam length. These basis functions can easily meet the requirement of high-order derivatives which come from the fifth-order shear deformation theory. In the reduced IGA, instead of establishing the finite element model with all degrees of freedom (DOFs), only a given number of DOFs are kept to derive the algebraic equation systems condensed in state space for damping vibration analysis. The vibration responses of beams with different boundary conditions, length-to-height ratios and damping intensities are studied. The reliability and the accuracy of the reduced-order IGA are verified by comparing the damping-free results with other existing publications. Meanwhile, the corresponding outcomes considering damping are reported and discussed in detail. Such solutions can be referred to by future research.

A Process-Based Framework for Early-Age Volumetric Stability in Foamed Controlled Low-Strength Material

2026-04-05T10:48:26+00:00

Early-age volumetric instability severely constrains the reliability of foamed controlled low-strength material (CLSM) when high foam fractions are required for lightweight backfilling. While prior studies emphasize compositional modification, this work demonstrates that geometric stability is primarily governed by shear history during mixing. A process-based framework was established to decouple process control from material stabilization in dredged-soil-based CLSM. Foam content (10–30%), mixing sequence (K, U1, U2), and rotational speed (30–120 rpm) were first evaluated to quantify shear-induced instability. As foam content increased from 10% to 30%, ΔV_Final increased from 1.47% to 19.82%, indicating a pronounced stability threshold beyond 25% foam. Under identical foam content, the staged-water method (U2) at 60 rpm reduced ΔV_Final to 5.91%, approximately 53–55% lower than the dry-mix condition, confirming the dominant role of mixing sequence and controlled shear. Material modifications acted as secondary stabilizers. Surfactant at 0.15% reduced ΔV_Final to 4.21% through interfacial reinforcement. FA replacement at 25% improved rheological cohesion, lowering ΔV_Final to 4.56%. Coconut fiber (0.20%) primarily enhanced structural integrity during setting (ΔV_Final = 4.89%). The integrated SFC configuration achieved ΔV_Final of 2.78% and 28-day compressive strength of 1.62 MPa, compared with 1.42 MPa for the baseline. The findings establish that early-age stability in foamed CLSM is process-dominant, with material strategies providing hierarchical reinforcement across interfacial, rheological, and structural scales. The proposed process–material integration framework establishes shear history as a governing design variable in foamed CLSM and provides a reproducible pathway for balancing lightweight performance with geometric stability in soft-ground backfilling applications.