17 Apr 2026

Restoring the Flexible Pavement Test Track to Monitor Impact of Military Ground Vehicles

Abstract: Full-scale tests for pavement design, construction, evaluation, and maintenance benefit from designated facilities where pavement elements can be controlled and monitored. A loop test track at the US Army Engineer Research and Development Center (ERDC) Vicksburg campus was constructed between September 1986 and September 1988. This report describes activities to restore that pavement test track through reconstruction. ERDC constructed a road structure consisting of 4 in. of asphalt concrete over 6 in. of aggregate base course over native subgrade material on the site of the original test track. The pavement structure was instrumented with earth pressure cells and moisture probes at the subgrade, or base, course interface. Material testing and as-constructed properties are documented herein to allow future traffic studies that use the constructed test track to create numerical simulations and calibrate their embedded models with real-world data. This report details construction activities and material properties for future reference.

14 Apr 2026

Verification and Validation of Modeling of Fluid–Solid Interaction in Explosion-Resistant Designs Using Material Point Method

Abstract: Verifying and validating explosion-resistant design models are challenging tasks due to the difficulties in accurately capturing the failure evolution within a setup influenced by the combined effects of fluid–solid interactions, blast waves, fragmentation, and impact. Curtain wall system, as a key structural component, is widely used in various types of buildings for its aesthetic appeal and weather protection. Hence, optimizing the explosion-resistance of such systems is necessary to improve building safety. In this work, we develop computational procedures that can be used to enhance the design of blast-resistant structures. This paper focuses on studying a representative component from a typical curtain wall system, as well as a small-scale modeling of shock tube testing. For that, the material point method simulations are verified against the finite element method simulations, and the computational results are validated against shock tube testing. The work objective is to evaluate the simulation fidelity of explosion responses in several case studies. The first case study demonstrates how the MPM captures damage and fragmentation in a typical confined explosion event involving FSI, thus, providing an improved physical description compared to the FEM. The second case study qualitatively compares the MPM’s ability to simulate the shock tube response with experimental observations. Since the second study validates that the MPM solution is qualitatively consistent with the experimental data, the MPM model is then used in the third case study to establish an FEM model that could capture the same physics. This FEM model can be scaled up to model field experiments. The fourth case study involves the development of an FEM model for a representative curtain wall system component, which is validated against experimental results and then scaled down and employed to validate a corresponding MPM model. The proposed procedure provides a feasible approach to verifying and validating explosion-resistant designs for more general cases.

13 Apr 2026

Silica Particulate Dispersion During Additive Friction Deposition in a Metal Matrix Composite

Abstract: This work presents a study of a low-power, solid-state additive manufacturing process to simultaneously mix and build a metal matrix composite. Specifically, an Al 6061 powder was blended with 11 wt% silica (SiO2) after which the powders were solid-state consolidated through additive friction stir deposition (AFSD). The inclusion of the SiO2 resulted in an average hardness of 70 ± 1 HV as compared to a control (no SiO2) of 52 ± 1 Hv. However, for the SiO2 composite, the hardness varied in both the radial build and vertical build directions, with the highest hardness found in the centerline of the deposit. This inhomogeneity has been contributed to differences in how the SiO2 particulates evolve during the stirring and mixing processes of AFSD. Furthermore, this variation in particulate evolution was found to be a useful marker in understanding the microstructure evolution through AFSD.

18 Mar 2026

An Updated Irwin Sensor for Measurement of Surface Shear Velocity

Abstract: Accurate and efficient collection of field data related to aeolian processes is critical for improving wind erosion predictions and related management decisions. The Irwin sensor has been used in numerous wind tunnel and field studies to indicate surface shear velocity. However, the sensitivity of the sensor makes them difficult to maintain in a range of environmental conditions. This study presents a new generation of Irwin sensor incorporating updated electronics, battery operation, wireless data transmission, and streamlined field deployment and removal. A total of 20 sensors were manufactured and calibrated in a wind tunnel at the Engineer Research and Development Center. A subset of the sensors was calibrated using a PI-SWERL, which confirmed the two calibration methods converge on similar values for flat smooth test surfaces. The updated sensors were installed around a mesquite shrub at the Jornada Experimental Range, New Mexico, USA from February to July 2023. We found that initial data from the sensors accurately captured spatial patterns of surface shear velocity surrounding the shrub. The improvements to the sensor reduced workload for both deployment and maintenance, and reduced disturbance at the field site. We discuss potential opportunities to use the improved sensor network in a range of geomorphological research areas including quantifying aeolian sediment transport, building and parameterizing wind erosion models that incorporate spatial dependencies, and improving predictive tools for landform change.

18 Feb 2026

Modeling the Service Life of Temporary Airfield Operational Surfaces Under Multi-Pass Aircraft Trafficking

Abstract: Expeditionary Airfield (EAF) surfacing systems are designed to create temporary aircraft operating surfaces. Modeling the service life of EAF surfacing systems including the matting system, aircraft, and subgrade, has historically proven difficult, exacerbated by variability between systems and the multitude of mechanisms that can constitute failure. The study presented herein outlines the development and implementation of a performance modeling approach that includes a multi-scale scheme that accounts for local characteristics of the connection points of the EAF matting system, coupled to the global characteristics of the matting array to predict cyclic passes to failure. Finite element studies were conducted for an EAF surfacing system brickwork configuration subjected to aircraft strut loads over varying California Bearing Ratio (CBR) subgrades to calibrate a transfer function to full-scale trafficking experiments. The proposed framework is then used to predict the rate of subgrade deformation for additional lay patterns, which successfully ranked the performance of each relative to full-scale trafficking experiments. An approach is proposed to couple the rate of subgrade deformation with local finite element models to capture increasing joint damage as permanent deformation accumulates, and supplemented by a variable amplitude cycle counting and damage accumulation algorithm that yields reasonable agreement with full-scale experiments while capturing the transition in failure mechanisms at higher CBR values. The results of the study presented herein captures the propensity for end connector and subgrade failure over a range of subgrade CBRs and shows promise for a broader performance framework that can be extended to other EAF surfacing systems, aircraft types, and specific matting lay patterns.

13 Feb 2026

Morphology-Driven Electromagnetic Shielding Performance of Graphitic Nanoparticles in Segregated Polypropylene Nanocomposites via Electromagnetic Melt Processing

Abstract: Electromagnetic melt-processing has emerged as an innovative and energy-efficient strategy for the structuring of thermoplastic nanocomposites. In this study, polypropylene (PP)-based TPNCs were fabricated using different grades of graphitic carbon nanoparticles to yield electrical conductivity and electromagnetic interference shielding effectiveness. The applied structuring methodology consists of a multiscale processing strategy that combines high-energy ball milling of polymer micro-pellets and CNPs, formulated powder compaction into green bodies, and EM-driven localized heating to produce the TPNCs. This enables the formation of highly segregated, percolated conductive networks at ultra-low filler loadings. The percolation threshold values for green bodies were significantly dependent on CNP morphology, ranging from approximately 0.50 wt% for low-aspect-ratio graphene nanoplatelets to around 1.0 wt% for medium-aspect-ratio carbon nanotubes. Upon EM melt-processing, due to viscoelastic deformation of CNP networks, the resulting threshold values of the structured TPNCs were approximately 0.73 wt%, 0.50 wt%, and 0.74 wt% for low, medium, and high aspect ratios, respectively. High-aspect-ratio CNTs, despite exhibiting greater structural defects, achieved the highest EMI SE of 19.7 dB/mm at 10 wt%, demonstrating that morphology dominates over graphitic crystallinity in governing transport properties and electromagnetic performance. Statistical modeling via response surface methodology confirmed the predictive significance of the CNP morphology and the concentration responses. This work underscores the critical influence of filler architecture and EM-induced structuring in enabling a novel, scalable platform for multifunctional polymer nanocomposites with enhanced electromagnetic shielding capabilities, offering promise for next-generation aerospace, electronics, automotive, and defense applications.

12 Feb 2026

Mechanical Properties and Microstructure of Annealed Ni/CrC-NiCr Metal Matrix Composite Prepared by Cold Sprayed Deposition

Abstract: This study investigates the effects of low (700 ◦C) and high (1000 ◦C) temperature annealing on the micro-structure and mechanical properties of two metal matrix composites consisting of Ni and two separate compositions of CrC-NiCr cold-sprayed onto A-514 structure steel. The mechanical properties, including tensile strength, ductility, interface shear strength, and microhardness, were evaluated after heat treatments. Additionally, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize the microstructure of the annealed deposits. The results showed that annealing significantly enhanced the inter-splat bonding quality between the matrix (nickel) particles. However, higher temperature annealing led to an increase in voids surrounding the cermet particle due to enhanced elemental diffusion. Furthermore, the interparticle bonding between the nickel particles in the matrix and the cermet particle was also improved after annealing. Depending on the composition, the ultimate tensile strength increased by a minimum of 32 %, and the adhesion shear strength improved by over 77 % following annealing at 1000 ◦C. Recrystallization and reduction of the dislocation density in the nickel matrix occurred within the splats during annealing, resulting in increased ductility from less than 0.2 % in the as sprayed condition to more than 6.5 % after annealing. However, a general reduction in hardness was observed after annealing. The interplay between the annealing temperature, microstructural evolution, and mechanical performance demonstrates that the improved bonding directly influenced the mechanical properties, resulting in increased tensile strength, greater ductility, and a shift from brittle to ductile fracture behavior as the micro-structure evolved.

5 Feb 2026

Evaluating Snow Pavement Strength in Remote Cold Environments via California Bearing Ratio (CBR) and Russian Snow Penetrometer (RSP) Combined Testing

Abstract: Accurate assessment of compacted snow strength is critical for ensuring the safety and performance of snow runways in cold environments. The Russian Snow Penetrometer (RSP) is widely used in snow science and engineering due to its simplicity, portability, and capability for rapid field measurements under extreme conditions. Conversely, the California Bearing Ratio (CBR) test remains the benchmark for evaluating the load-bearing capacity of conventional granular materials but is seldom applied to snow because of logistical constraints and the material’s complex mechanical behavior. The relationship between these two pavement evaluation tools remains poorly defined. This work investigates how RSP strength indices relate to CBR measurements to determine whether the RSP can serve as a practical proxy for snow pavement load-bearing capacity. Side-by-side field measurements of snow pavement strength were collected over a 30 h period at two test section locations. Both methods captured temporal strength increases and spatial variability, with consistently higher values at the second site attributed to extended sintering. A moderate linear correlation (R2 = 0.44) between RSP and CBR results supports a quantifiable relationship between the two methods. These findings begin to bridge the gap between conventional pavement testing and snow-specific strength evaluation, demonstrating the potential of the RSP for rapid assessment of snow runways. Continued data collection and analysis will refine this relationship and strengthen its applicability for operational use.

30 Jan 2026

Well-Defined Glycopolymer Chitosan Mimics for Design of Chitosan Nanocomposites

Abstract: Chitosan, a naturally derived polysaccharide with intriguing antimicrobial and polycationic properties, is highly desirable as a biosourced and biodegradable material for biomedical, food packaging, and personal care applications. Its inherent high levels of variability in molecular weight, dispersity, and degree of deacetylation, however, make the establishment of structure− property−processing relationships difficult and limit materials development. In this study, a novel methacrylate-based glycomonomer with saccharide structure similar to that of chitosan was synthesized and copolymerized with methyl methacrylate via reversible addition−fragmentation chain-transfer (RAFT) polymerization to create a series of well-defined chitosan mimics with controlled molecular weights and low dispersity (<1.1). Evaluation of mammalian cytotoxicity and antibacterial activity against Escherichia coli and Staphylococcus aureus revealed performance similar to that of chitosan. The copolymers were used as models to evaluate difficult-to-probe interactions between chitosan and graphene oxide (GO) and elucidate mechanisms of mechanical property improvements observed in chitosan/GO nanocomposite films.

28 Jan 2026

Lightweight Deflectometer (LWD) Evaluation of Low Volume Road Structural Deterioration Under Military Traffic Loads

Abstract: In a combat zone, military vehicles may not have the benefit of traveling on well-constructed pavements, necessitating the use of low volume roads (LVR) to transport personnel and cargo. Military vehicles can cause rapid structural damage to LVRs that are not designed to withstand increased traffic loads. Currently, rapid pavement infrastructure assessment techniques for military personnel are based on qualitative visual inspections which do not provide estimates for structural capacity of the pavement. The objective of this project was to determine whether the lightweight deflectometer (LWD) can be used as a structural evaluation tool for LVRs in contingency operations. This study explored the capability of LWD equipment in evaluating factors that influence flexible pavement structural capacity: load-induced deterioration, soil moisture, and asphalt temperature. Falling-weight-deflectometer (FWD) and LWD tests were performed to measure pavement structural condition. The LWD was shown to be applicable for LVRs experiencing military traffic. The LWD is portable, simple to use, and more suitable than the FWD for LVRs when high rut depths are permitted. LWD data trended similarly to FWD data and therefore can be recommended as an alternate to the FWD in assessing the structural condition of LVRs for contingency planning.