Structural and Impact Performance Analysis of a Tensegrity-Inspired Helmet Liner for Impact Mitigation

Lim, Chye Huat (2026) Structural and Impact Performance Analysis of a Tensegrity-Inspired Helmet Liner for Impact Mitigation. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Traumatic brain injuries (TBI) that occurred from falls, sports collisions, and especially automobile accidents continue to be a major concern today. The needs of wearing helmet for both motorcycle and bicycle users are necessary in order to reduce death rate and traumatic brain injury. Conventional helmet liners made of expanded polystyrene (EPS) foam provide only limited protection under complex impact conditions, especially oblique impacts that generate both linear and rotational accelerations. This restriction emphasises the need for alternatives liner designs that can enhance energy absorption efficiency and lower peak accelerations without sacrificing weight. The current study intends to solve this issue by examining the impact performance and structural integrity of a helmet liner inspired by tensegrity for impact mitigation. The objective of this study is to develop a parametric model of tensegrity-inspired helmet liner using Grasshopper tool in Rhino3D to integrate the tensegrity structure into standard geometries of helmet liner. The effect of different material, unit cell numbers and strut diameters of the tensegrity-inspired helmet liner will be investigated by the mechanical properties and energy absorption capabilities especially the specific energy absorption (SEA) using quasi-static compression simulation in ANSYS Static Structural. The impact performances will be assessed at linear and 45◦ oblique impacts on various impact velocities of 6m/s, 7.5m/s and 8m/s based on the head injury metrics of PLA, PRA, HIC, and BrIC using dynamic impact test simulation in ANSYS LS-DYNA. According to the results, a 9x9 unit cell numbers of tensegrity-inspired helmet liner with material of Polyamide 12 and strut diameter of 1.8mm improved the overall structural efficiency by 43.7% with safe initial peak load of 3221.8N, light mass of 94.74g and standard SEA value of 0.8945J/g compared to the parametric model developed. The impact performance of the optimized tensegrity-inspired helmet liner is superior at low-to-standard impact velocities of 6m/s and 7.5m/s which PLA is reduced by at least 28% and HIC by 40% which PLA is dropped from 269G to 193G and HIC values is reduced from 2399 to 1363 for impact velocity of 7.5ms. Early structural densification is occurred which tensegrity liner failed to perform at high impact velocity of 8m/s. Violent force spike up to 973G PLA is obtained from the high impact energy. The tensegrity liner also showed signs of being susceptible to rotational forces which it did not perform better than conventional helmet liner in oblique impacts due to the asymmetric loading and geometric friction of the liner design. In conclusion, the tensegrity-inspired helmet liner developed holds a great potential to improve the conventional helmet liner as several baselines set by the motorcycle and bicycle helmet standards such as ECE R22.06, ECE R22.05, CPSC and CEN 1078 are passed