Search Results (139)

Flexible polyurethane (PUR) foams and latex rubber foams are widely used in furniture and mattress cushioning, yet conventional standardized mechanical tests only partially capture comfort-relevant behavior, particularly in layered constructions where material interactions and sequencing can alter elastic response. This study aimed to compare the mechanical (elastic) properties of selected three-layer composites of approximately 60 mm thickness (composed of conventional PUR, high-resilience PUR, low-resilience PUR, and latex foam) and to preliminarily assess whether combining foam types improves support of such setup and whether changing layer order modifies elasticity and support. Indentation hardness testing of multilayer cushions was conducted by ISO 2439:2008 Method E. Six three-layer systems (Alpha–Zeta) were assembled in two groups. Group X showed nearly identical support factors (2.6–2.7), high recovery (64.3–66.2%), low hysteresis loss (24.3–24.5%), and overlapping force–indentation (IFD) curves, indicating minimal effect of layer order and dominance of the PUR layers. Group Y exhibited higher but more sequence-dependent support (3.1–3.7), markedly reduced, wider range recovery (30.0–45.9%), increased hysteresis (33.0–34.7%), and more dispersed IFD curves. Placing high-resilience foam at the top partially improve recovery, whereas locating low-resilience foam at the surface increase energy loss. The research contributes in part to the body of knowledge about the behavior of the tested materials according to standardized rules. These preliminary results can be compared with other research findings and used in the preparation of testing models for multilayer foam composites, thereby generating new knowledge to improve the design of future experiments, which will result in increased sitting and lying comfort. Full article

The design of cushioning packaging for flat-screen television (TV) products relies heavily on repeated simulations, resulting in high development costs and low design efficiency. In this study, we propose a hybrid framework integrating finite element (FE) simulation, data augmentation and interpretable machine learning (ML) for rapid peak acceleration prediction and optimization of TV cushioning packaging. First, a total of 216 FE drop-impact simulation samples of TV cushioning packaging systems were generated using ANSYS Workbench, covering TV dimensions, liner type, liner density, liner thickness, drop height and peak acceleration. Mixup-based data augmentation and Bayesian optimization were then employed to develop and tune six ML models. All ML models trained on the original dataset achieved coefficients of determination (R²) ranging from 0.797 to 0.990. The Mixup-augmented XGBoost model achieved the best prediction performance, yielding R² values of 0.998 and 0.983 for the training and testing datasets, respectively. SHAP analysis revealed that liner material type, liner density and liner thickness were the dominant factors affecting the protective performance of TV cushioning packaging. In addition, a web-based platform was developed based on the proposed FE–ML strategy to support the design exploration of feasible schemes for new TV products. The predictive capability of the proposed FE-ML framework was further evaluated using 22 independent cushioning packaging schemes, achieving an R² of 0.926 and an average prediction error of 4.490 g. These results suggest that the proposed workflow can support the performance evaluation and optimization of TV cushioning packaging. Full article

To mitigate impact damage to airdropped supplies during landing, this study proposes a cushioning pad design method based on the C − σm (cushioning coefficient–maximum stress) curve, aiming to balance energy absorption efficiency with lightweight requirements. A medium-sized airdrop impact simulation model is established and validated via drop impact tests, and systematic dynamic impact analyses are performed on three representative cushioning materials: honeycomb paperboard, polyurethane foam, and aluminum foam. Their cushioning characteristic curves are compared, revealing that all three materials exhibit a concave C − σm profile (first decreasing, then increasing) with distinct optimal stress ranges for airdrop cushioning applications: aluminum foam for high stress (≥500 kPa), polyurethane foam for medium stress (350–450 kPa), and honeycomb paperboard for low stress (≤200 kPa). The energy absorption potential decreases with the optimal stress threshold, while cushion thickness positively correlates with the airdrop load range. In the low-stress stage, the maximum stress shows a strong functional dependence on energy density, rendering thickness effects negligible for energy absorption. Under the material fragility constraint, the C − σm curve-based graphical method can accurately determine the cushion pad’s optimal thickness and bearing area. In design Case 3, optimizing the bearing area reduced the required cushion thickness from 100.5 cm to 25.0 cm, substantially decreasing the cushion volume. The findings provide reliable material-level insights and theoretical support for impact protection design in airdrop cargo, with clear guidance on selecting cushioning materials based on their intrinsic mechanical response. Full article

As a widely used sponge facility, the permeable pavement system (PPS) frequently exhibited a decline in pollutant removal after long-term operation. However, the long-term impacts of different cushion fillers on pollutant removal and ecological risk remain unclear. This study modified a conventional sand-based PPS (S1) by replacing the cushion layer with five materials: construction waste bricks (S2), coal gangue (S3), activated carbon (S4), carbon nanotubes (S5), and graphene (S6). A 5-year laboratory experiment evaluated the removal efficiency, fraction distribution, and ecological risk of heavy metals (HMs: Mn, Pb, Zn, Cu, Cd, Ni) from rainfall. The key findings demonstrated significant variations among fillers. S2 showed the poorest performance with a removal efficiency of 83.26% ± 13.02 across all HMs, whereas carbonaceous-modified systems (S4–S6) exhibited high removal efficiencies, exceeding 97.00% ± 1.89. Residual and Fe/Mn oxide states were predominant among the HMs, exceeding 43.69%, indicating enhanced metal immobilization. The ecological risks of carbon nanotubes and graphene were the highest, with risk indices of 1123.02 and 1129.63, respectively. These findings demonstrated that carbonaceous fillers achieved superior HM sequestration, leading to an overall reduction in ecological risk in the effluent of PPS after long-term operation. Overall, this study provided new perspectives on elucidating long-term removal efficiency and the ecological risk mitigation of PPS, and supported future application of carbonaceous fillers in sustainable PPS design and construction. Full article

Silicone rubber foam is widely used in multi-field engineering protection due to its excellent cushioning and thermal insulation properties. However, its performance degradation caused by long-term service aging seriously affects equipment reliability. Establishing a constitutive model that can accurately characterize the mechanical response during aging is crucial for studying performance degradation and finite element simulation. Traditional multi-parameter aging constitutive models suffer from problems such as easy convergence to local optimal solutions and poor physical interpretability of parameters. To address these issues, this study systematically characterizes the evolution laws of the stress–strain response, compression set, and stress relaxation of silicone rubber foam over an aging period of 0–768 h through accelerated thermal aging and uniaxial compression tests and proposes a second-order Ogden aging constitutive model with a single time-varying parameter. This model fixes α₁, α₂, and μ₂ as constants and only sets μ₁ as the time-varying parameter, reducing the number of parameters to be fitted from four to one. The coefficient of determination (R²) of the full-cycle stress–strain curve fitting is ≥0.9966. Meanwhile, a quantitative physical correlation between μ₁ and macroscopic aging performance indicators is established, enabling the direct prediction of the mechanical response of aged materials using measurable macroscopic indicators. This work provides an efficient and reliable modeling method for the aging performance evaluation and structural simulation of silicone rubber foam. Full article

This paper develops a shock-absorbing asphalt mixture for pedestrian pavements that mitigates the impact of normal walking on pedestrians’ bodies by incorporating crumb rubber from recycled tires to produce a soft mixture. This aims to reduce injuries to vulnerable road users, enable the rethinking of urban pavement designs, and address the major challenges facing societies, ultimately achieving more sustainable, resilient, and safer cities. To promote land sustainability, the designed asphalt mixture should be pervious, allowing water to infiltrate into the underlying soil. The development of the asphalt mixture followed an experimental methodology that involved formulating asphalt mixtures with conventional bitumen, polymer-modified bitumen, and bituminous emulsion. The shock-absorbing capability was evaluated by measuring the deformation of the asphalt mixture over time in response to a falling weight from a Light Falling Weight Deflectometer. Permeability capabilities were assessed through the permeability test. Subsequently, the asphalt mixture was characterized according to its macrotexture, friction, air void content, rutting resistance, and stiffness to assess its suitability as a walking surface material. Results indicate that increasing rubber content enhances deformation capacity and improves cushioning but reduces stiffness. Among the solutions, mixtures with polymer-modified bitumen and intermediate rubber content achieved the balance between impact attenuation and mechanical performance. Full article

Background: A novel titanium scleral buckle implant (TSBI) was developed for the treatment of posterior pole retinal detachments, analytically modeled and structurally tested as part of preclinical approval studies. The strength and stiffness requirements to apply pressure for retinal reattachment also suggested potential benefits for correcting high myopia greater than 8 diopters. Methods: Laboratory load testing and analytical calculations were complemented by nonlinear finite element modeling (FEM), applied for the first time to capture the interaction between the highly deformed myopic eye and the TSBI. Simulations were used to visualize posterior pole indentation and force distribution across anatomical regions. Seven TSBI units were tested in the transverse direction and six in the longitudinal direction. Results: The simulations confirmed that stable indentation is maintained even in areas distant from the sutures. The TSBI’s minimum midspan bending capacity was 40 N at yield and 60 N at ultimate. These values, together with FEM predictions, demonstrated a very large safety margin and showed that the implant deforms insignificantly under high intraocular pressure changes. Conclusions: The TSBI withstands ocular forces, cushions the sclera safely, and retains its geometry, a behavior that may differ from softer buckle materials, which can exhibit time-dependent deformation under sustained loading. Early controlled clinical applications outside the USA, followed for over three years, further validate its safety and potential effectiveness. Full article

Airborne electromagnetic (AEM) surveys map subsurface electrical structures by deploying transmitter and receiver coils on an airborne platform. However, platform-induced vibrations are transmitted to the sensors, generating strong motion-induced noise that severely degrades signal quality. To mitigate such noise, this study proposed the use of granular materials as a cushioning medium. An impact model based on the Discrete Element Method (DEM) was developed and validated against drop-weight experiments. Both granular material properties and impactor characteristics were investigated. The study examined the cushioning effects on both the base plate and the impactor under impact loading, and the sensitivity of key parameters was evaluated. The results showed that granular properties had minimal influence on the impactor peak force. Increasing particle Young’s modulus, density, or friction coefficient led to higher peak forces on the base plate, with Young’s modulus and density having significantly stronger effects than friction coefficient. Additionally, both the impactor size and velocity correlate positively with the peak forces transmitted to the base plate and experienced by the impactor. Under thin layer conditions, the impactor force was more sensitive to impact parameters, while in thick layers it was mainly determined by particle rearrangement and energy dissipation mechanisms. These findings reveal the mechanisms governing granular cushioning and provide a theoretical basis for vibration isolation design in AEM systems to preserve high-fidelity signals. Full article

The paw pad is an outstanding cushioning structure, which demonstrates nonlinear mechanical characteristics when subjected to pressure. Nonlinear mechanical characteristics are generally considered to be related to the viscoelastic properties of the material. However, the relationship between its nonlinear mechanical properties and the morphological characteristics of the paw pad remains unknown. In this study, morphological data, mechanical data, and finite element simulation methods were integrated to explore how the unique shape of the paw pads enables them to exhibit excellent cushioning performance. The research findings indicate that the paw pad exhibits an irregular morphology. Nevertheless, its cross-sectional area increases in proportion to the increase in the paw pad height, presenting a linear gradient relationship (R² = 0.99). Two comparison models with the same volume and height but different morphologies as the paw pad model, were designed for finite element simulation. The finite element static analysis shows that the influence of morphology is mainly reflected in the early deformation process, while the influence of viscoelastic material properties is reflected in the later load-bearing capacity. The finite element dynamic analysis shows that compared with the comparison models, the paw pad model has a more stable force during the impact process, without an instantaneous impact force at the initial contact moment. Moreover, the peak normal ground reaction force (GRF) component under different impact speeds is lower than that of the comparison models, demonstrating better buffering effects. The research results can provide inspiration and a biomechanical basis for the morphological design of buffering units. Full article

The proliferation of single-use petroleum-based foams in protective packaging has become a major source of persistent plastic waste, posing significant challenges to environmental sustainability. To address this issue, we developed a fully biodegradable cushioning foam from bamboo, a rapidly renewable biomass, using an environmentally benign deep eutectic solvent (DES) process that avoids harsh chemical bleaching. The resulting lignin-containing cellulose nanofibril (LCNF)/sodium alginate (SA) foam exhibits low density (0.23 g/cm³), high compressive strength (0.24 MPa at 70% strain), and excellent elasticity (90% recovery at 50% strain), enabled by a dual-network structure of Ca²⁺-crosslinked SA and entangled LCNFs. Critically, the material is fully compostable and leaves no microplastic residues, offering a circular end-of-life pathway. In real-world banana drop tests, it matched the performance of commercial expanded polyethylene (EPE) while outperforming polyethylene bubble wrap. This work demonstrates a practical, scalable route to replace fossil-derived cushioning materials with a bio-based alternative that aligns with the principles of cleaner production and circular economy. Full article

In response to the high stiffness and hardness levels of alumina ceramic materials, the traditional SHPB (split Hopkinson pressure bar) experimental setup has been modified. This study analyzes the propagation patterns of stress waves in the SHPB system after adding cushion blocks. Experiments demonstrated that the modified SHPB apparatus can effectively perform dynamic mechanical property tests on alumina ceramics. The JH-2 constitutive damage model parameters for alumina ceramics were determined based on theoretical analysis and static/dynamic experimental data. An LS-DYNA numerical model for the impact compression simulation of alumina ceramics was established to investigate the effects of stress waves with three wavelengths (300 mm, 400 mm, and 600 mm) at the same impact velocity, along with the dynamic fragmentation process. The results indicate that alumina ceramics exhibit strain rate hardening effects in compressive strength, failure strain, and elastic modulus under high strain rates; compressive strength and failure strain show positive correlations with stress wave wavelength under high strain rates; and microcracks initially nucleate preferentially along grain boundaries on the end surfaces, forming annular damage zones symmetrically about the central axis. This study presents a modified SHPB setup that improves test capability for high-hardness ceramics, rather than overturning classical methodologies. The absence of a direct comparison with unmodified setups stems from the known limitations of conventional systems in handling small-diameter alumina specimens without bar damage—a challenge addressed proactively in this work through impedance-matched cushion blocks and refined data processing. Full article

In transient high-pressure gas rock breaking, resilient sealing materials can reduce energy loss during rock breaking and ensure the effectiveness and safety of the operation. This study, utilizing experimental data and finite element analysis, investigates the impact of transient high-pressure gas on sealing methods. It compares the traditional single-layer concrete sealing with a novel three-stage concrete sealing method, highlighting its advantages. Furthermore, a three-stage approach is used to analyze the mechanical evolution of different sealing layers, and the sealing mechanism is revealed through energy-absorption analysis. Research findings indicate that the traditional single-layer concrete sealing method experiences severe damage, with a maximum damage value of 0.26. In contrast, the three-stage sealing method exhibits significantly less damage (mostly < 0.2), effectively improving sealing efficiency. The three-stage sealing method generally demonstrates lower stress levels compared to the single-layer concrete sealing method. After passing through the gravel and soil layers, the impact-induced stress becomes relatively stable, with stress levels at the center gradually approaching those at the hole’s walls. The central portion of the gravel layer shows a greater energy absorption effect than the two boundary areas, while the soil layer exhibits a linear relationship between deformation and energy absorption. The three-stage sealing method weakens the impact through a structural approach of “pressure-absorption-pressure”, where the gravel layer primarily disperses pressure, while the soil layer provides energy absorption and cushioning. The research findings have significant implications for the safe application of transient high-pressure gas rock breaking technology. Full article

The bioinspired superhydrophobic surfaces have demonstrated many fascinating performances in fields such as self-cleaning, anti-corrosion, anti-icing, energy-harvesting devices, and antibacterial coatings. However, developing a low-cost, feasible, and scalable production approach to fabricate robust superhydrophobic surfaces has remained one of the main challenges in the past decades. In this paper, we propose an uncommon method for the fabrication of a durable superhydrophobic coating on the surface of the glass slide (GS). By utilizing the screen printing method and high-temperature curing, the epoxy resin grid (ERG) coating was uniformly and densely loaded on the surface of GS (ERG@GS). Subsequently, the hydrophobic silica (H-SiO₂) was deposited on the surface of ERG@GS by the impregnation method, thereby obtaining a superhydrophobic surface (H-SiO₂@ERG@GS). It is demonstrated that the micro-grooves in ERG can provide a large specific surface area for the deposition of low surface energy materials, while the micro-columns can offer excellent protection for the superhydrophobic coating when it is subjected to mechanical wear. It is important to note that micro-columns, micro-grooves, and nano H-SiO₂ jointly form the micro–nano structure, providing a uniform and robust rough structure for the superhydrophobic surface. Therefore, the combination of a micro–nano rough structure, low surface energy material, and air cushion effect endow the material with excellent durability and superhydrophobic property. The results show that H-SiO₂@ERG@GS possesses excellent self-cleaning property, mechanical durability, and chemical stability, indicating that this preparation method of the robust superhydrophobic coating has significant practical application value. Full article

Spacer fabrics are a breathable material option for wearable cushioning, but the cushioning performance is still not comparable to that of traditional elastomeric cushioning materials. The polymer-based connective structure of spacer fabrics largely affects fabric properties, compression, and mechanical performance, and this is a research gap that calls for the development of spacer fabrics with enhanced cushioning functions. This study develops a new square-wave inlay pattern and investigates the effects of the inlay structure and spatial frequency of the spacer course, as well as the effects of the silicone inlay on compression, impact force absorption, and vibration isolation of the spacer fabric. Twelve samples are designed and evaluated. The results show that the square-wave inlaid spacer fabric has higher energy absorption during compression. The square-wave pattern with a shorter transition distance between the front and back tuck stitches could increase the inclination angle close to a right angle, and extra tuck stitches on the surface float could secure the square-wave structure to enhance the impact force absorption ability. The increment in the spatial frequency of spacer courses provides a less stiff fabric with lower impact force absorption but higher vibration isolation ability. This study shows the innovative development of spacer fabric for enhancing cushioning properties. Full article

Mechanical damage and microbial contamination are major challenges in the postharvest logistics of perishable fruit. In this study, two types of functionally modified chitosan-based aerogel pads were developed to enhance cushioning and preservation of wax apples. A chitosan/polyvinyl alcohol (CP) aerogel was first optimized by adjusting solid content, CS:PVA ratio, and crosslinker concentration. The optimal formulation (2% solids, 1:1 CS: PVA, 3% glutaraldehyde) exhibited a uniform porous structure and improved compressive strength. A chitosan/montmorillonite (CM) aerogel with 5% montmorillonite (MMT) showed high porosity, low density, and excellent cyclic stability. Incorporating 10% copper nanoparticle-loaded antibacterial fibers (CuNPs-TNF) into CM aerogels yielded CM-Cu aerogels with enhanced cushioning and antimicrobial properties. Under simulated transport and cold storage conditions, all aerogel-packaged groups reduced mechanical damage and decay of wax apples. Compared to the control, the CM-Cu group showed 66% lower decay, 5% less weight loss, 6 N greater firmness, 7% less juice yield, and a 13% reduction in relative electrical conductivity. Additionally, it better preserved fruit color and total soluble solids, extending shelf life by 4 d at 20 °C. These results demonstrate the potential of chitosan-based aerogels as multifunctional packaging materials that combine mechanical protection with antimicrobial activity for perishable fruit preservation. Full article