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<p>3D printed wheelchair cushions made from flexible thermoplastic polyurethane gyroid structures enable highly customized shape and stiffness, offering superior pressure offloading for those at risk of pressure injuries. However, there is currently a limited understanding of how non-uniform stiffnesses can be leveraged in design to realize this potential, highlighting a need for improved numerical methods. To this end, this work presents the first finite element model representative of the seated buttocks on a 3D printed cushion using a novel non-linear homogenization approach. Next, a gradient-free lattice optimization approach for optimising the 3-dimensional stiffness distribution across the cushion for reducing maximum contact stress is also presented. Using our approach, the optimized 3D printed cushion had a 42% reduction in maximum contact stress compared with a uniform stiffness cushion and a 31% reduction compared with a traditional contoured foam polyurethane cushion design. The deep soft tissue stress under the ischial tuberosities (sit-bones) also decreased by 39% following optimization. This model suggests that 3D printed cushions can offer significant advantages in pressure offloading, which could translate to improved health outcomes and highlights a promising avenue for future work. The homogenization approach for representing variable stiffness gyroid structures may be used in future work to inform the design of 3D printed wheelchair cushions for clinical applications.</p>

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Design of a 3D printed wheelchair cushion for offloading using functionally graded materials and novel FEM topology optimization

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月5日

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  • Rachel Tilley,
  • Edmund Pickering,
  • Maria Woodruff,
  • David Holmes

摘要

3D printed wheelchair cushions made from flexible thermoplastic polyurethane gyroid structures enable highly customized shape and stiffness, offering superior pressure offloading for those at risk of pressure injuries. However, there is currently a limited understanding of how non-uniform stiffnesses can be leveraged in design to realize this potential, highlighting a need for improved numerical methods. To this end, this work presents the first finite element model representative of the seated buttocks on a 3D printed cushion using a novel non-linear homogenization approach. Next, a gradient-free lattice optimization approach for optimising the 3-dimensional stiffness distribution across the cushion for reducing maximum contact stress is also presented. Using our approach, the optimized 3D printed cushion had a 42% reduction in maximum contact stress compared with a uniform stiffness cushion and a 31% reduction compared with a traditional contoured foam polyurethane cushion design. The deep soft tissue stress under the ischial tuberosities (sit-bones) also decreased by 39% following optimization. This model suggests that 3D printed cushions can offer significant advantages in pressure offloading, which could translate to improved health outcomes and highlights a promising avenue for future work. The homogenization approach for representing variable stiffness gyroid structures may be used in future work to inform the design of 3D printed wheelchair cushions for clinical applications.