Abstract
The combined effects of explosive shock waves and high-velocity fragments pose critical challenges to the structural integrity of protective systems. Traditional experimental approaches often oversimplify the problem, lacking systematic investigation into how fragment geometry and foam density gradients influence the synergistic damage mechanisms. To address this gap, this study proposes a novel composite projectile consisting of gradient aluminum foam embedded with rigid fragments of various contact-end shapes (cylindrical, hemispherical, and truncated conical). Finite element models were developed and validated against experimental data to analyze the effects of fragment shape, embedding depth, loading sequence, and foam density gradient on loading characteristics and target plate responses. Results reveal that fragment geometry significantly affects the stress distribution and failure modes of the target plate. Hemispherical fragments, due to their smaller initial contact areas, induce concentrated stress and early penetration, thereby weakening the combined loading effect. Additionally, gradient foam composition regulates the contact force profile, with higher front-end densities producing stronger initial forces but shorter interaction durations. These findings offer new insights into the design and optimization of gradient composite projectiles for simulating realistic explosive loading conditions and improving structural impact resistance.
Similar content being viewed by others
Data availability
The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.
References
Arnold, J. L. et al. Mass casualty terrorist bombings: a comparison of outcomes by bombing type[J]. Ann. Emerg. Med. 43, 263–273 (2004).
Kong, X. S. et al. Experimental and numerical investigation on a multi-layer protective structure under the synergistic effect of blast and fragment loadings[J]. Int. J. Impact Eng. 65, 146–162 (2014).
Zhou, N. et al. Study on the failure mode of a sandwich composite structure under the combined actions of explosion shock wave and fragments[J]. Mater. Des. 196, 109166 (2020).
Lim, J. Y. et al. Structural response of steel-concrete composite panels to near field simultaneous blast and fragmentation loading [J]. Int. J. Impact Eng. 195, 105142 (2025).
Wang, J. X. et al. Study on damage characteristics of sandwich plate under the combined action of explosion shock wave and randomly distributed fragments[J]. Ocean. Eng. 309, 118575 (2024).
Liang, M. Z. et al. Failure mode and blast resistance of polyurea coated metallic cylinders under internal multi-field coupled loading[J]. Thin Wall Struct. 184, 110522 (2023).
Li, W. et al. The deformation and failure mechanism of cylindrical shell and square plate with pre-formed holes under blast loading[J]. Def. Technol. 17 (4), 1143–1159 (2021).
Li, L. et al. Computational analysis of sandwich panels with graded foam cores subjected to combined blast and fragment impact loading[J]. Materials 16 (12), 4371 (2023).
Zhang, P. et al. Experimental investigation into the synergetic damage of foam-filled and unfilled corrugated core hybrid sandwich panels under combined blast and fragment loading[J]. Compos. Struct. 299, 116089 (2022).
Hu, W. & Chen, Z. Model-based simulation of the synergistic effects of blast and fragmentation on a concrete wall using the MPM[J]. Int. J. Impact Eng. 32, 2066–2096 (2006).
Nyström, U. & Gylltoft, K. Numerical studies of the combined effects of blast and fragment loading[J]. Int. J. Impact Eng. 36, 995–1005 (2009).
Ebrahimi, H. et al. Honeycomb sandwich plates subjected to combined shock and projectile impact[J]. Int. J. Impact Eng. 95, 1–11 (2016).
Zhang, C. et al. Numerical investigation of the response of I-core sandwich plates subjected to combined blast and fragment loading[J]. Eng. Struct. 115, 459–471 (2017).
Marx, J., Portanova, M. & Rabiei, A. A study on blast and fragment resistance of composite metal foams through experimental and modeling approaches[J]. Compos. Struct. 194, 652–661 (2018).
Wu, G. et al. Damage response of polyurea-coated steel plates under combined blast and fragments loading[J]. J. Constr. Steel Res. 190, 107126 (2022).
Atoui, O. et al. Dynamic Behavior of Aluminum Plates Subjected To Sequential Fragment Impact and Blast Loading: an Experimental Study[J]. Appl Sci-Basel. Vol. 13, 3542 (2023).
Ranwaha, N. & Yuen, S. C. K. The effects of blast-induced fragments on cellular materials[J]. Int. J. Impact Eng. 92, 50–65 (2016).
Li, J. et al. Numerical investigation of composite laminate subjected to combined loadings with blast and Fragments[J]. Compos. Struct. 214, 335–347 (2019).
Li, D. et al. Experimental study on the combined damage of multi-layered composite structures subjected to close-range explosion of simulated warheads[J]. Int. J. Impact Eng. 114, 133–146 (2018).
Zhang, C. et al. Numerical investigation of the response of I-core sandwich panels subjected to combined blast and fragment loading[J]. Eng. Struct. 151, 459–471 (2017).
Li, Y. et al. Experimental and numerical study on damage mode of RC slabs under combined blast and fragment loading[J]. Int. J. Impact Eng. 142, 103579 (2020).
Li, Y. et al. The influence of different pre-formed holes on the dynamic response of square plates under air-blast loading[J]. Eng. Fail. Anal. 78, 122–133 (2017).
Rakvåg, K. G. et al. Transient pressure loading of clamped metallic plates with pre-formed holes[J]. Int. J. Impact Eng. 53, 44–55 (2013).
Aune, V. et al. On the dynamic response of blast-loaded steel plates with and without pre-formed holes[J]. Int. J. Impact Eng. 108, 27–46 (2017).
Rathore, R. K. et al. Mechanical properties of lightweight aluminium hybrid composite foams (AHCFs) for structural applications[J]. Adv. Mater. Process. Technol. 8 (4), 4194–4208 (2022).
Singh, N. K. et al. Effect of Reinforcement on Micro Structural and Compressive Deformation Behavior on Closed Cell AA7075 Aluminium foam[J]. J. of Mine., Metal. & Fuel. Vol. 72(2) (2024).
Malviya, M. K. et al. A Review on aluminum metal matrix composites: processing and properties[J]. Computational Optimization, Modeling, and Simulation for Engineering Applications, pp: 73–80. (2024).
Singh, N. K. & Sethuraman, B. Development and characterization of aluminium AA7075 hybrid composite foams (AHCFs) using SiC and TiB2 reinforcement[J]. Int. J. Metalcast. 18 (1), 212–227 (2024).
Singh, N. K. & Balaguru, S. Fabrication and mechanical characterization of Al-Zn-Cu Alloy/SiC/TiB2 hybrid reinforced metal matrix composite using top loaded bottom pouring stir casting method[J]. Silicon 16 (1), 45–59 (2024).
Rathore, R. K., Singh, N. K. & Xavier, J. F. Characterization of AA7075 alloy foam using calcium and magnesium carbonate as foaming agent[M]//Processing and Characterization of Materials: Select Proceedings of CPCM 2020. Singapore: Springer Singapore, pp: 289–297. (2021).
Li, L. et al. A laboratory experimental technique for simulating combined blast and impact loading[J]. Int. J. Impact Eng. 134, 103382 (2019).
Yu, R. P. et al. Dynamic response of fully-clamped steel plate under laboratory-simulated sequential fragment impact and blast loading[J]. Thin Wall Struct. 182, 110144 (2023).
Radford, D. D., Deshpande, V. S. & Fleck, N. A. The use of metal foam projectiles to simulate shock loading on a structure[J]. Int. J. Impact Eng. 31, 1152–1171 (2005).
Rathbun, H. J. et al. Performance of metallic honeycomb-core sandwich beams under shock loading[J]. Int. J. Solids Struct. 43, 1746–1763 (2006).
Chang, B. X. et al. Crashworthiness design of graded cellular materials: an asymptotic solution considering loading rate sensitivity [J]. Int. J. Impact Eng. 143, 103611 (2020).
Chang, B. X. et al. Crashworthiness design of graded cellular materials: experimental verification of the backward design strategy[J]. Int. J. Impact Eng. 171, 104366 (2023).
Ashby, M. F. et al. Metal Foams: a Design guide[M]. Oxford: Butterworth – Heinemann (2002).
Frontán, J., Zhang, Y. & Ming, D. Ballistic performance of nanocrystalline and nanotwinned ultrafine crystal steel[J]. Acta Mater. 60, 1353–1367 (2012).
Børvik, T., Hopperstad, O. S. & Berstad, T. Numerical simulation of plugging failure in ballistic penetration[J]. Int. J. Solids Struct. 38, 6241–6264 (2001).
Li, L., Xue, P. & Luo, G. A numerical study on deformation mode and strength enhancement of metal foam under dynamic loading[J]. Mater. Des. 110, 72–79 (2016).
Acknowledgements
The authors are grateful for financial supports of Project funded by China Postdoctoral Science Foundation (2021M702537), Natural Science Foundation of Hubei Province of China (2021CFB029), Opening projects of Hubei Province Key Laboratory of Systems Science in Metallurgical Process (Wuhan University of Science and Technology, Y202408), and State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering (Jianghan University, PBSKL2023B11).
Author information
Authors and Affiliations
Contributions
P. Jiang and W. Zhang wrote the main manuscript text, C.X. Wu contributed to data collection and prepared all the figures, X.Y. Wang contributed to literature search, L.J. Cai, D.W. Zhong, and J.J. Ma provided resources.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Jiang, P., Wu, C., Wang, X. et al. Tailoring combined impact loading using gradient foam composite projectiles with variable fragment shapes. Sci Rep (2026). https://doi.org/10.1038/s41598-026-38606-4
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-38606-4
