Laser powder bed fusion (L-PBF) of thermosetting polymers remains challenging due to competing requirements of powder flowability, controlled melt coalescence, and in-situ crosslinking. This study systematically investigated a thermoplastic polyurethane (TPU) modified epoxy (EP) thermosetting powder system processed via selective laser polymerization (SLP) approach within the L-PBF framework at low temperatures (60-65 degrees C). An optimized formulation containing 30 wt% TPU (30TPU/EP) enables simultaneous TPU softening and epoxy-amine crosslinking during laser exposures, forming a partially crosslinked semi-interpenetrating polymer network. Powder flowability, optical absorptivity, and thermal behavior are systematically correlated with SLP processability, while a Taguchi design of experiments employed to optimize processing parameters for achieving low porosity, high dimensionally accuracy, and stable multilayer consolidation. Comprehensive characterizations using FTIR, DSC, and FE-SEM confirmed in-situ and post-curing reactions, degree of cure and uniform phase dispersion. Thermo-mechanical performance evaluated using DMA, TMA, tensile testing (across build orientations), digital image correlation, and impact testing demonstrated glass transition temperature above 113.5 +/- 2 degrees C, reduced thermal expansion (66.44 mu m/mK below Tg), pronounced anisotropy in tensile strength (8.86-17.99 MPa), along with enhanced impact resistance (10.06 +/- 0.89 kJ/m2). Powder reuse over five cycles revealed minimal aging without chemical degradation, confirming good reusability. Overall, the 30TPU/EP system demonstrated a potential thermosetting feedstock for low-temperature L-PBF, enabling the fabrication of mechanically robust and geometrically complex structures for high-performance applications in aerospace, automotive and biomedical.

Conventional additively manufactured cellular structures primarily dissipate energy through irreversible crushing, whereas recoverable cellular structures absorb energy through controlled deformation, enabling repeated use. This study presents a novel mechanical metamaterial as spring-inspired corrugated closed cell cellular lattice structure that is fabricated via FFF using thermoplastic polyurethane (TPU) material, in which groove number serves as a geometric tuning parameter for mechanical performance without altering material, external global dimensions, or any manufacturing complexity. Quasi-static cyclic compression experiments were performed across multiple groove configurations, wall thicknesses and displacement rates. The experimental results revealed that groove number is the dominant parameter governing stiffness, plateau characteristics and hysteresis-based energy dissipation for repeated loading cycles. A functionally graded configuration achieved graded inclined plateau response through sequential layer engagement of variable stiffness cells, demonstrating a multistage dissipation advantage. A new phenomenological mathematical model simultaneously capturing loading and unloading hysteresis loop, is developed using physical representation of nonlinear elasticity, plateau, and densification regions, based on equivalent Maxwell element with nonlinear spring-damper elements. The model incorporates the rate effects through the inclusion of displacement rate term, which enabled representation of viscoelastic behavior at different loading conditions. It clearly demonstrates its geometric configuration dependence, supporting its relevance beyond empirical fitting. It establishes its significance as a computationally efficient, reduced-order approach for indicating the nonlinear mechanical response of recoverable spring-inspired cellular lattice structures.

This study reports a hybrid additive-manufacturing and material-processing workflow for the fabrication of an advanced, lightweight energy-absorbing composite. A mathematically defined spherical waveform shell geometry optimized for progressive buckling was fabricated using polycarbonate (PC) material via the Fused Filament Fabrication (FFF) process. These shells are filled sequentially with engineered UV-curable foam resin containing microwave expandable microspheres, followed by in-situ UV curing. Upon microwave exposure, the filled core, having excellent dielectric properties, absorbs the microwave energy, foaming volumetrically, while the PC shell with low dielectric properties remains structurally intact. The compression behavior at different deformation rates were systematically investigated and compared to unfilled and equivalent-weight unfilled shells. Experimental results show that the filled shell and core architecture fundamentally transforms the failure mode from unstable global buckling to stable progressive crushing. Furthermore, the filled composite shell exhibited substantial enhancement in crashworthiness metrics, with specific energy absorption SEA of 5.19 J/g, a 69% and 138% improvement over unfilled and equivalent weight designs, respectively. Similarly exceptional crushing force efficiency CFE of 1.04 was achieved for filled specimens at a deformation rate of 50 mm/min. This integrated methodology, combining tailored geometry, material formulation, and sequential hybrid processing, establishes a digitally controllable and scalable route for next-generation high-performance composite structures for a diverse range of applications.

Passive damping systems that combine high dissipation capacity with rate-adaptive response and structural reusability remain challenging to realize using conventional single architected materials, which are typically governed by purely structural damping mechanisms, while conventional fluid dampers require complex assembly. Here, a novel viscous fluid-encapsulating cellular mechanical system (CMS) is realized as a complete damping device, in which energy dissipation is enhanced through orifice-governed viscous dissipation, activated by the coupling of compliant cellular deformation rather than material damage, while generating velocity-dependent hydraulic resistance. The architected CMS was fabricated as a single monolithic unit via single-step additive manufacturing without post-processing. The fluid-filled CMS was systematically investigated for quasi-static and dynamic testing, delivering substantially enhanced ED for filled CMS, 183.7% more at 1000 mm/min than empty, while both configurations exhibited near-identical values at quasi-static rates (328 vs 379 mJ at 10mm/min), confirming negligible hydraulic contribution below the threshold speed. Similarly, an exceptional improvement of 194% in loss factor was observed, while SED increased from 0.17 to 0.39 at maximum speed. Under dynamic loading conditions, the filled CMS exhibited pronounced optimal operating frequency-dependent behavior, with ED 162.8% higher than the empty one at 1Hz and moderating to 138.7% at 2.5 Hz. The design strategy opens a new avenue for additively manufactured lightweight adaptive cellular hydraulic damping devices, enabling proportional scaling with lattice size, for a diverse range of energy dissipation applications.

Passive damping systems combining high dissipation capacity, rate-adaptivity and cyclic durability remain unrealised in conventional architected materials (purely structural damping mechanism), while conventional fluid dampers require complex assembly. Here, we present a novel cellular mechanical system (CMS), in which orifice-governed viscous dissipation is activated by the coupling of compliant cellular deformation, while the encapsulated fluid generates velocity-dependent hydraulic resistance in parallel with structural viscoelasticity. Unlike conventional fluid dampers, the CMS is fabricated monolithically via single-step additive manufacturing without post-processing or assembly. Flow regime analysis confirms viscous flow conditions for the silicone oil configurations (Re < 1), establishing the applicability of linear viscous orifice resistance across the full tested parameter space. Under quasi-static compression (10-1000 mm min(-1)), the fluid filled CMS achieves a specific energy dissipation of 68.5 J kg(-1) at 1000 mm min(-1), 116% higher than that of the empty configuration, while both give nearly identical dissipation at 10 mm min(-1), confirming a speed threshold for hydraulic contribution. The loss factor reaches 0.062 at 1000 mm min(-1), 121% above the empty structure. A parametric study shows that raising viscosity from 0.1 Pa s to 1.0 Pa s increases specific energy dissipation by 92% and reducing orifice diameter from 3.0 to 1.5 mm increases it by 62%. Under dynamic cycling testing at 1.0-2.5 Hz over 400 cycles, the filled CMS sustains a loss factor that is 85-107% higher than that of the empty configuration, with a cyclic stability index of 88-91% and no leakage or structural failure. This design establishes a cyclically stable, rate-adaptive, and geometrically tunable platform for additively manufactured cellular hydraulic dampers.

Barium titanate (BaTiO3)is a lead-free piezoelectric ceramic material that exhibits superior electromechanical and dielectric properties. However, achieving dense, defect-free structures via vat photopolymerization remains a challenge due to viscosity limitations and light scattering at high-solid-loading. To overcome these challenges, this study presents a water-washable BaTiO3 slurry optimized for Digital Light Processing (DLP) through a combined materials and process design. The interplay between the particle size, rheology, and curing behavior is investigated, showing that finer particles enhance slurry yield stress and particle packing density but increase optical attenuation, while coarser particles improve curing depth. To overcome flow-induced defects at high viscosity, a multi-point slurry injection strategy is introduced in the custom-made DLP system that reduces flow distance and enables uniform layer formation. The system achieves dense ceramics with a maximum relative density of 96.34 %. Microstructural analysis confirms tetragonal phase formation with controlled grain evolution, where an optimal sintering temperature of 1350 degrees C yields the highest flexural strength for 0.2 mu m particle size (38.24 MPa), and the highest hardness (389.3 HV) was achieved at 1400 degrees C. This work establishes a process-structure-property relationship for fabricating dense BaTiO3 ceramic components with improved printability and structural integrity.

Post-print thermal foaming of additively manufactured expandable resins offers a useful route for producing lightweight cellular structures, but the role of printed architecture in the activation process is not yet well understood. This study examines topology-controlled convective foaming of vat photopolymerization (VPP)-printed composite resin structures containing expandable microspheres and fumed silica. Four lattice architectures, Gyroid, Honeycomb, Diamond, and Schwarz-P, were compared with a Solid reference in terms of activation time, volumetric expansion, pore morphology, and compressive response. A geometry-accessibility framework was introduced using total surface area, characteristic heat-transfer length, projected open-area ratio, and openness continuity. A coupled transient thermal–static structural finite element model was also used to examine topology-dependent heating and equivalent macroscopic expansion. Gyroid showed the shortest mean activation time of 365s, followed by Honeycomb (390s), Diamond (406s), and Schwarz-P (566s), although the differences among Gyroid, Honeycomb, and Diamond were relatively small. The non-mass-matched Solid reference required 1800 s. Honeycomb showed the highest volumetric expansion ratio of 8.5 and the largest mean equivalent pore diameter of 98.8 ± 22.2µm. Exploratory regression showed that activation time was associated with surface area (R2 = 0.776, p = 0.048), characteristic heat-transfer length (R2 = 0.992, p < 0.001), and projected open-area ratio (R2 = 0.971, p = 0.002). However, no single descriptor reproduced the complete activation sequence among the investigated structures. The FE model captured the general macroscopic expansion trends, with relative errors of 2.6-20.0% across the five configurations. Under low-rate compression, Honeycomb provided the highest SEA among the lattice structures at 3.97 ± 0.20J/g and the lowest apparent density of 66.1kg/m3. These results show that printed architecture affects heat accessibility, geometric restraint, foam expansion, and the resulting mechanical response during post-print thermal foaming.

This study presents a novel auxetic mechanical structure (AMS) designed to reduce recoil in stents application. Building upon a peanut-shaped auxetic lattice with a negative Poisson’s ratio, various single- and double-layer AMS configurations were developed by integrating friction-based (clamp, tubular, elliptical interlocking) and locking-based (locking, ratchet) mechanisms. Finite element analysis (FEA) and additive-manufactured prototypes were employed to evaluate mechanical performance, focusing on recoil mitigation, expansion uniformity, and structural integrity. Results demonstrated that locking-based mechanisms significantly improve recoil resistance, reducing recoil to 3.9% in the single-layer locking design and 5.4% in the double-layer ratchet design, compared to 100% recoil in unmodified structures. Friction-based mechanisms provide moderate improvements but require optimization of clamping force and contact area. Despite minor increases in relative density, AMS designs maintain the auxetic response and expand effective surface area, advantageous for drug delivery. Overall, the AMS approach provides a robust and adaptable design strategy for reducing recoil on auxetic structure. However, further optimization and validation across different auxetic geometries and materials are required to enhance clinical applicability.

Post-traumatic knee replacement (PTKR) is frequently complicated by the presence of retained metallic hardware around the joint, which limits the use of intramedullary alignment guides. Consequently, extramedullary jigs are often required, although they may increase radiation exposure and reduce alignment precision. Patient-specific guides (PSGs), generated from medical imaging and produced via 3D printing, offer a potential alternative for improving accuracy in complex surgical scenarios. This study aimed to assess the accuracy of PSGs in PTKR using in-vitro knee models with and without retained hardware. CT images of arthritic knees were used to generate 3D-printed anatomical models. Metallic plates and screws were subsequently mounted to replicate typical post-traumatic hardware configurations. These phantoms underwent CT scanning for virtual surgical planning, and patient-specific guides (PSGs) were designed based on the reconstructed preoperative models. In-vitro distal femoral and proximal tibial resections were then performed by a surgeon using the corresponding PSGs. After the simulated procedures, all phantoms were re-scanned to quantify PSG positioning accuracy and resection angles. Knee phantoms with hardware exhibited shape deviations 17–18.5 times greater than those without hardware (p < 0.05). PSG positioning errors averaged 0.68 mm and 2.83° in hardware models, compared to 0.55 mm and 1.32° in non-hardware models. Resection angle errors in hardware phantoms ranged from 2.4° to 3.1°, significantly higher than in the non-hardware group. Based on the in-vitro experimental findings, PSGs allow PTKR to be performed without the removal of retained hardware while achieving accuracy that exceeds that of traditional extramedullary alignment techniques. Although hardware presence results in a quantifiable reduction in accuracy, PSGs continue to demonstrate improved alignment precision and contribute to enhanced workflow efficiency in the context of complex PTKR.

Innovative material design is crucial to the advancement of additive manufacturing (AM) technologies, particularly for producing lightweight high-performance components. This work presents a novel epoxy–polyurethane hybrid material system engineered for laser powder bed fusion (L-PBF) to fabricate and evaluate complex triply periodic minimal surface (TPMS) lattice structures. By integrating high stiffness and thermal resistance of epoxies with toughness and elasticity of polyurethanes, the hybrid material system achieves an optimal balance of rigidity, energy absorption, and durability, critical for lightweight structural applications with tunable mechanical properties. In this study, three type of TPMS lattice architectures, including gyroid, diamond, and Schwarz-P, were fabricated using novel duroplastic formulations of Epoxy-amine (EP) modified with varied weight proportions of thermoplastic polyurethane (TPU) (20 to 60 wt%) and their mechanical performances such as strength, stiffness, and energy absorption capability were experimentally characterized under quasi-static compression. Results highlight the strong dependence of mechanical performance on both, material composition and lattice architectures. Diamond lattices exhibited the highest compressive strength, stiffness, and energy absorption fabricated with 30/70 TPU/EP formulation. All the fabricated duroplastic TPMS lattices achieved more than 60% weight reduction while retaining high compressive strength and recoverability, surpassing the performance of conventional thermoplastics with comparable designs. These findings underscore the potential of TPU/EP hybrid systems in driving the next generation of lightweight structurally efficient and sustainable lattice architectures for high-performance aerospace, automotive, biomedical, and advanced engineering applications.

Epoxy-based thermosetting polymers, valued for superior thermal stability and mechanical performance, remain underutilized in Laser-based powder bed fusion (PBF/LB) due to limited melt-flow and premature gelation during laser irradiation, impede interlayer bonding and brittle structures. To address, this study investigates thermoplastic polyurethane (TPU)-modified epoxy (EP) thermosetting powder system designed to enhance processability through controlled formation of semi-interpenetrating polymer networks during selective laser polymerization. A synergistic coupling of TPU improves laser-energy absorption, melt coalescence, and diffusion-assisted epoxy crosslinking, thereby suppressing premature vitrification. The EP powder was dry blended with varied TPU content (20–60 wt%) and characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) to evaluate morphology, thermal transitions, and curing mechanisms. Non-isothermal cure kinetics reveal enhanced network evolution via multistage curing pathway with delayed gelation. The influence of key process parameters on consolidation behaviour was systematically investigated, and optimized conditions were established through morphological and density analyses of fabricated specimens. A kinetic-driven multistage postcuring further promotes diffusion-controlled network development, increasing the degree of cure from ∼45% to near-complete conversion without significant warpage. The optimized 30/70 TPU/EP composition exhibited high thermal stability (Tg > 130 °C, degradation onset >285 °C) and improved mechanical performance. Successful fabrication of complex lattice geometries confirms processability and structural integrity. This work establishes a process-structure-property framework and demonstrated that TPU-modified epoxy thermosets enable low-power PBF/LB, providing a scalable route for manufacturing high-performance thermoset components for advanced engineering applications.

Interpenetrating phase composite (IPC) is a unique type of material that may exhibit tunable mechanical and functional properties. This study introduces a novel hybrid material extrusion (MEX) technique to fabricate lattice-based IPC metamaterials. This approach aims to functionally tune mechanical properties by incorporating diverse material phases within the lattice voids. Two different designs—sea urchin (SU) and hybrid (H) lattice were 3D printed using thermoplastic polyurethane (TPU) as the outer material. The lattice voids were filled with combinations of polyamide (PA)-12 powder, 316L stainless steel-based slurry, and polyurethane (PU) foam, resulting in three IPC configurations (IPC- type I: foam-powder-powder, IPC- type II: foam-slurry-powder, and IPC- type III: foam-slurry-slurry). Comprehensive static and dynamic compression tests were conducted to evaluate the mechanical properties of the resulting IPC metamaterials. Hybrid lattice-based IPC metamaterials demonstrated superior mechanical properties compared to their SU counterparts. IPC-type I demonstrated a substantial improvement in mechanical performance, exhibiting a compressive strength up to 5 times higher and an energy absorption per unit volume up to 2.5 times greater than empty or single-phase metamaterials. Under dynamic conditions, both designs showed distinct properties in hysteresis work, tan δ, and dynamic elastic recovery (DER). The study also explores the effects of varying loading rates and frequencies on the IPC metamaterials' mechanical behavior. Overall, this study presents an innovative fabrication technique for IPC metamaterials, revealing how the strategic placement and stacking sequence of secondary materials within the primary structure significantly influences their mechanical properties.

Medial open-wedge high tibial osteotomy (MOWHTO) is effective for treating medial-compartment knee osteoarthritis but carries a risk of lateral hinge fractures (LHF), compromising stability and outcomes. Hinge holes and protective K-wires reduce LHF by lowering stress and enhancing lateral support. However, their combined effect has not been evaluated. This study investigates whether using both techniques together can more effectively reduce lateral cortical bone stress and prevent LHF during MOWHTO. This study combined finite element analysis (FEA) and in-vitro compression testing to evaluate stress distribution and fracture behavior during MOWHTO. Three-dimensional models reconstructed from osteoarthritic CT images were used, with consistent definitions of wedge, hinge, and protective K-wire placement. Compression testing models were 3D-printed for cost efficiency and repeatability. FEA simulated stress during wedge opening, while compression testing measured load-gap curves, fracture load, and fracture patterns. Hinge holes alone reduced hinge stress by 14.4

Liquid crystal display (LCD) vat photopolymerization (VPP) is gaining popularity in both industry and research due to its cost-effectiveness compared to other polymer-based 3D printing methods. However, surface quality remains a critical limitation, primarily due to the black matrix present between the active pixels of the LCD panel. Pixelation and staircase effects significantly degrade the surface finish and functional performance of printed parts. In this study, a voltage-tunable polymer-dispersed liquid crystal (LC) film is introduced as a secondary optical interface between the LCD panel and the resin vat. By varying the input voltage, the LC film enables tunable light scattering, diffuses sharp pixel boundaries, and smooths the projected mask image. This results in up to 95% reduction in surface roughness compared to the standard No LC condition. Improved surface smoothness enhances interlayer bonding, reduces stress concentration zones, and leads to substantial gains in tensile and flexural strength, including energy absorption. Additionally, the light transmittance of printed parts improves without post-processing. A resolution study confirms that features down to 2-pixel width remain resolvable, satisfying the Rayleigh criterion. This scalable and hardware-compatible strategy effectively enhances surface quality and mechanical performance in LCD VPP without compromising resolution.

Additive manufacturing has progressed beyond a single material processing technique through the integration of advanced material sciences and artificial intelligence technologies. The present study introduces the concept of digital metallurgy in AM, a novel methodology that combines multi-material, computational alloying, tessellation, and secondary material-filled closed cell lattices. Utilizing these technologies in AM digital metallurgy allows the creation of compositionally graded, functionally graded, and geometrically complex parts tailored to specific applications. The multi-material AM, particularly metals, allows the integration of computational tools and combines different alloys to achieve tailored mechanical properties. This includes the use of advanced machine learning algorithms for in-situ monitoring to address interface issues, cracking, and porosities between dissimilar materials. The extrusion-based metal and ceramic additive manufacturing processes are also reviewed. The concept of digital metallurgy through low-cost, multi-material metal and ceramic AM processes is presented, which can be further extended to high-entropy alloys and advanced ceramics. The tessellated design framework draws inspiration from a variety of metallurgical phases, which results in versatility in the design, optimized material usage, and structural integrity of the components. Secondary material-filled closed-cell lattice further leverages AM by incorporating non-printable materials to enhance mechanical and functional properties that are not achievable with open-cell lattice structure. An in-depth discussion of the challenges and future applications of digital metallurgy in AM emphasizes its significance for industries such as automotive, aerospace, and biomedical engineering. The combined approach of digital metallurgy in AM addresses all the critical bottlenecks of material compatibility, properties prediction, and process optimization. This systematic review offers new horizons for the sustainable development of AM within the framework of industry 4.0.

A stress-field-driven transfemoral prosthetic socket design was developed using functionally graded lattice structures and fabricated through a multi-material extrusion-based additive manufacturing process. Polyethylene terephthalate glycol (PETG) and thermoplastic polyurethane (TPU) were strategically assigned to the outer and inner regions of the socket, respectively, to achieve an optimal balance of structural rigidity and localized flexibility. Material and mechanical characterization of the individual polymers and their interface demonstrated intermediate mechanical behaviour at the PETG-TPU boundary. Spectral analysis revealed shifts in the carbonyl (−C=O) and urethane (−N−H) peaks, indicating intermolecular interactions and partial miscibility at the interface. Lattice configurations, including body-centered cubic (BCC) and gyroid structures, were evaluated with and without graded density variations. A radially graded gyroid lattice was selected based on its superior deformation response, with a 25 mm cell size exhibiting approximately 1 mm compression under a 950 N load. The final socket demonstrated a maximum deformation of 6 mm under a 400 N mechanical load. These results demonstrate the effectiveness of integrating finite element-based stress mapping with digital design and multi-material fabrication in producing lightweight, anatomically conforming, and patient-specific prosthetic sockets.

Additive Manufacturing (AM) has revolutionized the production of intricate geometries tailored to customized functional mechanical properties, making it widely adopted across various industries, including aerospace, automotive, and biomedical sectors. However, the fabrication of mechanical springs has remained largely constrained by conventional manufacturing techniques, which limit their cross-sectional geometries to regular shapes, thereby restricting their mechanical performance and energy absorption capabilities. This limitation poses a significant challenge in applications where enhanced load-bearing capacity, energy absorption, and tailored stiffness characteristics are required. To address this issue, this study investigates the influence of coil shape on the mechanical properties of wave springs, specifically focusing on load-bearing capacity, energy absorption, stiffness, and compression behavior during cyclic loading and unloading. Nine contact-type wave springs with distinct coil shapes—square, rectangular, pentagonal, hexagonal, heptagonal, octagonal, quadro, circular (4 waves per coil), and circular (6 waves per coil)—were designed and fabricated using MultiJet Fusion (MJF) technology. Uni-axial compression testing was conducted over ten loading–unloading cycles to evaluate their mechanical performance and deformation characteristics. The results indicate that wave springs with square and rectangular coil shapes exhibit the highest energy absorption while maintaining the lowest stiffness and minimal energy loss during the first ten loading–unloading cycles. Furthermore, experimental findings were validated using finite element analysis (FEA) under identical boundary conditions, demonstrating close agreement with a deviation of only 2.3% compared with the experimental results. These results highlight AM’s potential for customizing wave springs with optimized mechanical performance.

Among all polymer-based 3D printing technologies, liquid crystal display (LCD)-based vat photopolymerization (VPP) has emerged as a promising method, offering high resolution and cost-effectiveness through large-area LCD panels. However, its adoption is hindered by two key challenges: surface roughness caused by the LCD's black matrix and interface adhesion with the LCD panel. This study introduces a non-sticky display (NSD) approach using sub-micron structured polydimethylsiloxane (PDMS) film laminated onto the LCD panel to address both issues simultaneously. The optimized NSD 2000 configuration achieves an 82.5% reduction in surface roughness while preserving print resolution through controlled light diffusion. Its sub-micron structured surface creates a stable Cassie state by trapping air, imparting hydrophobic properties and low work of adhesion. Additionally, the PDMS layer eliminates electrostatic adhesion between oppositely charged surfaces, such as Teflon (interface) and the LCD panel, effectively resolving the interface adhesion issue. This reduces separation energy by up to 52% for high-viscosity foam resin and an 8-fold reduction of separation force for acrylate-based fast-curing resin. The successful printing of large-scale, complex geometries with challenging materials and the improved mechanical and optical properties of the printed parts demonstrate the NSD approach's potential for advancing LCD VPP to develop functional parts.

This study presents a novel 3D printing process for combining two different phases of material: liquid and solid. A closed-cell lattice structure designed for support-free printing, allowing the entrapment of liquid in its empty spaces, thus forming a liquid-entrapped architected structure. The structures are additively manufactured using a simultaneous printing and filling process without any post-processing operation. This is achieved using a hybrid material extrusion (MEX) setup, which has a modified secondary nozzle that dispenses the liquid on demand after the primary nozzle finishes its layer printing process. This simultaneous printing and filling process requires no post-processing operations and greatly reduces fabrication time. These structures are made using thermoplastic polyurethane (TPU) and subsequently filled partially (60%) and fully (100%) with silicone oil. Experimental and numerical quasi-static compression tests are conducted on partially and fully filled global architected structures, and are compared with unfilled structures. A substantial enhancement in effective stiffness and energy absorption (EA) is observed in the post-transition phase. By varying the quantity of liquid, effective stiffness and EA can be passively controlled with precision, to achieve tunable mechanical properties. The ability to tune the mechanical and functional properties holds great potential for a wide range of energy-absorbing applications.