Researchers at San Diego State College’s (SDSU) Experimental Mechanics Laboratory and Superior Manufacturing Hub have developed 3D printed steady carbon fiber “meta-skins” designed to enhance influence mitigation in composite foam-core buildings. Printed in Additive Manufacturing Letters, the examine by Sean Eckstein, Sophia Benkirane, and George Youssef evaluates pseudo-woven composite skins fabricated utilizing automated tow placement (ATP) and compares monocoque and sandwich configurations below low- and moderate-velocity influence. The outcomes present that optimum efficiency relies on influence regime, with single-skin buildings performing higher at decrease speeds and two-skin sandwich designs offering improved mitigation at greater velocities.
Pseudo-woven structure through automated tow placement
The examine stories the fabrication of steady carbon fiber composite skins utilizing a robotic ATP system. Somewhat than producing a traditional cross-ply laminate, the researchers created a pseudo-woven construction composed of alternating 0° and 90° tow sublayers. The interlaced structure goals to enhance load distribution and delamination resistance in comparison with conventional cross-ply laminates. Every successive sublayer was shifted laterally by 6 mm, forming an interwoven sample by way of the laminate thickness.
As much as 40 sublayers had been stacked to provide 2 mm-thick meta-skins. These skins had been bonded to cylindrical polyurea foam pucks in two configurations. Within the monocoque design, a single meta-skin capped the froth core. Within the sandwich configuration, the froth was enclosed between two meta-skins. The target was to guage how structural configuration and pores and skin structure affect dynamic influence response.
Low-velocity testing favors monocoque design
Low-velocity influence experiments had been carried out with a drop tower system. A 2.7 kg hemispherical impactor hit the specimens at 4.43 m/s. Excessive-speed imaging and digital picture correlation (DIC) tracked full-field pressure and deformation throughout influence.
Beneath these situations, the monocoque configuration exhibited decrease peak drive and longer influence period than the sandwich construction. The one-skin design produced a decrease peak drive and an extended influence period, suggesting extra spread-out vitality absorption. The researchers hyperlink this to larger foam involvement, which lets the fabric deform inside its hyper-viscoelastic plateau area. The monocoque samples absorbed almost 100% of the influence vitality and outperformed cross-ply benchmarks by roughly 15%, regardless of having a decrease fiber quantity fraction (29 vol.% versus 48 vol.%).
Power–time histories, pressure distributions, and quantitative metrics together with impulse and absorbed vitality confirmed that the absence of a backside pores and skin enabled larger foam compression and vitality dissipation at decrease influence speeds.
Sandwich configuration performs higher at greater velocity
To evaluate greater strain-rate conduct, the staff carried out moderate-velocity influence exams at 15 m/s utilizing a small-scale shock tube to speed up a projectile.
At this velocity, the efficiency pattern reversed. The sandwich configuration lowered peak drive by roughly 26% in comparison with the monocoque construction. Velocity–time information revealed a number of contact occasions throughout influence, suggesting altered stress-wave interactions inside the confined foam core. Digital picture correlation and post-impact floor reconstructions indicated that the second pores and skin promoted extra uniform compression and lowered shear at elevated influence charges. The researchers conclude that structural confinement supplied by the underside pores and skin turns into advantageous below sooner influence situations.
Structure-dependent dynamic efficiency
Throughout each influence regimes, the outcomes reveal that mitigation efficiency relies upon strongly on structural configuration and loading fee. The monocoque design gives improved efficiency at decrease velocities, whereas the sandwich construction presents enhanced safety below moderate-velocity influence.
By leveraging automated tow placement to manufacture pseudo-woven steady fiber architectures, the examine demonstrates how 3D printed composite skins may be engineered to tailor stress distribution, injury evolution, and vitality absorption in foam-core programs.
Steady fiber composites and architected supplies in additive manufacturing
Steady fiber reinforcement has turn out to be a central focus in additive manufacturing because the sector shifts from prototyping towards structural, load-bearing purposes. Current developments in steady fiber deposition programs, together with defense-backed efforts to advance course of simulation and mechanical predictability, spotlight the rising demand for performance-driven composite AM options. These initiatives underscore the significance of understanding how printed fiber architectures behave below advanced and dynamic loading situations.
On the similar time, additive manufacturing has enabled the rise of architected and metamaterial-inspired buildings designed to tailor mechanical response by way of geometry. Analysis into additively manufactured acoustic metamaterials has demonstrated how inner structure can be utilized to control wave propagation and stress distribution in methods not doable with standard fabrication. Although targeted on acoustics, such work illustrates the rising emphasis on architected supplies, the place structural geometry dictates efficiency, an method mirrored within the SDSU examine.
Composite materials innovation has additionally expanded in parallel, with high-performance strengthened polymer programs being positioned for aerospace and industrial environments. Nevertheless, a lot of that development has centered on materials chemistry and reinforcement content material. The current examine shifts consideration towards fiber topology and structural configuration, exhibiting how additively manufactured steady fiber architectures can affect influence mitigation throughout completely different velocity regimes. In doing so, it reinforces the rising function of architected composite design in next-generation structural purposes.
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Featured picture exhibits schematic of the pseudo-woven steady carbon fiber meta-skin fabricated utilizing automated tow placement (ATP), together with experimental setups for low-velocity drop tower and moderate-velocity shock tube influence testing. Picture through Eckstein et al., Additive Manufacturing Letters.