---
title: "Design and testing of FFF-printed PLA honeycomb sandwich panels for flexural strength and mass eff"
id: "plos-one-1-experimental-investigation-and-multi-response-design-of-fff-printed-pla"
canonical_url: "https://medichelpline.com/clinical-feed/plos-one-1-experimental-investigation-and-multi-response-design-of-fff-printed-pla"
content_type: "clinical_feed_article"
specialty: "General"
source_name: "PLOS ONE (Medicine)"
source_url: "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0358969"
published_at: "2026-09-21T14:00:00.000Z"
evidence_level: "Journal Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Design and testing of FFF-printed PLA honeycomb sandwich panels for flexural strength and mass eff
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/plos-one-1-experimental-investigation-and-multi-response-design-of-fff-printed-pla
- **Specialty:** [General](https://medichelpline.com/clinical-feed/general.md)
- **Primary Source:** PLOS ONE (Medicine)
- **Source URL:** [Original Journal Publication](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0358969)
- **Published At:** 2026-09-21T14:00:00.000Z
- **Evidence Rating:** Journal Feed
## Executive GIST (TL;DR)
- This experimental study evaluated how four geometric parameters—**honeycomb cell size (HCS)**, **cell-wall thickness (HCT)**, top face-sheet thickness (TFS), and bottom face-sheet thickness (BFS)—affect the nominal flexural strength and mass of fused filament fabrication (FFF) printed polylactic acid (**PLA**) honeycomb sandwich panels. - Eighteen geometric configurations were fabricated using a mixed-level Taguchi L18 orthogonal array; one specimen per configuration was printed and tested, plus one confirmation specimen for the selected compromise design. - Fabrication used commercial PLA filament (1.75 mm, eSUN) on a PRATHAM 5.0 FFF machine with a 0.4 mm nozzle. Constant printing settings included 210 °C extrusion temperature, 100% nominal infill, 0.2 mm layer height, 30 mm/s print speed, 55 °C bed temperature, and cooling fan off. Some slicer toolpath settings (extrusion width, perimeter count) were not recorded. - Three-point bending tests followed ASTM D7249/D7249M-20 arrangement with a nominal span-to-height ratio ≈3:1; crosshead speed was 2 mm/min and loading nose diameter 30 mm. Maximum load was used to compute the reported nominal **flexural strength** for each specimen. The original maximum-load values and calculation sheet were not available in the accessible records. - ANOM identified factor levels favoured separately by maximum flexural strength and minimum mass. ANOVA quantified relative parameter contributions: for flexural strength, **HCS** contributed 45.9% and **HCT** 34.1%; for panel mass, **HCT** contributed 50.9% and **HCS** 34.0% of modelled variation. - Because the factor levels that maximize strength differ from those that minimize mass, the authors combined ANOM factor levels with normalized ANOVA contributions in a contribution-weighted multi-response selection procedure to choose a compromise configuration. - The selected compromise configuration (HCS = 6 mm, HCT = 1.08 mm, TFS = 1.18 mm, BFS = 1 mm) produced a measured flexural strength of 13.21 MPa and mass of 34.367 g in the validation experiment. This design retained 90.54% of strength of the highest-strength L18 configuration while reducing mass by 50.29% relative to that highest-strength configuration. - The study concludes that core-related variables (HCS, HCT) accounted for most modelled variation in both measured responses within the investigated design space, and that the contribution-weighted procedure provided a transparent, study-specific means to reconcile competing response-specific factor settings. - Limitations in the accessible record include missing slicer-perimeter/extrusion-width settings, absence of replicated specimens (one specimen per configuration), lack of original maximum-load calculation sheet, and no systematic failure-mode classification in the dataset provided.
## Clinical Analysis & Structured Key Points
Experimental investigation and multi-response design of FFF-printed PLA honeycomb sandwich panels for flexural performance and mass efficiency | PLOS One Browse Subject Areas ? Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Article Authors Metrics Comments Media Coverage Reader Comments Figures Figures Abstract Lightweight sandwich structures produced by fused filament fabrication (FFF) require geometric designs that provide adequate mechanical performance without excessive material usage. However, the geometric parameters governing flexural response and structural mass can favour different design configurations, making response-specific parameter selection unsuitable when both requirements must be considered simultaneously. This study experimentally investigates the effects of honeycomb cell size (HCS), honeycomb cell-wall thickness (HCT), top face-sheet thickness (TFS), and bottom face-sheet thickness (BFS) on the flexural strength and mass of FFF-printed polylactic acid (PLA) honeycomb sandwich panels. Eighteen geometric configurations were fabricated according to a mixed-level Taguchi L18 orthogonal array and evaluated by three-point bending and mass measurement. Analysis of means (ANOM) was used to identify response-specific factor levels, while analysis of variance (ANOVA) quantified the relative contributions of the geometric parameters. HCS and HCT accounted for 45.9% and 34.1% of the modelled variation in flexural strength, respectively, whereas HCT and HCS accounted for 50.9% and 34.0% of the modelled variation in panel mass. Because the parameter settings favoured by maximum flexural strength differed from those favoured by minimum mass, the ANOM factor levels were combined with normalized ANOVA contributions in a contribution-weighted multi-response selection procedure. The resulting configuration, HCS = 6 mm, HCT = 1.08 mm, TFS = 1.18 mm, and BFS = 1 mm, produced a flexural strength of 13.21 MPa and a mass of 34.367 g in the validation experiment. Compared with the highest-strength L18 configuration, the selected design retained 90.54% of the measured flexural strength while reducing panel mass by 50.29%. The results indicate that the core-related variables accounted for most of the modelled variation in the two measured responses. Within the investigated design space, the contribution-weighted procedure was used as a study-specific means of reconciling the response-specific factor settings and selecting a candidate strength–mass compromise for experimental evaluation. Citation: Yelamasetti B, Agarwal A, Thotakuri M, Sushma ISP, Choden J, Kumar P N, et al. (2026) Experimental investigation and multi-response design of FFF-printed PLA honeycomb sandwich panels for flexural performance and mass efficiency. PLoS One 21(9): e0358969. https://doi.org/10.1371/journal.pone.0358969 Editor: Miran Merhar, University of Ljubljana Biotechnical faculty: Univerza v Ljubljani Biotehniska fakulteta, SLOVENIA Received: July 15, 2026; Accepted: September 8, 2026; Published: September 21, 2026 Copyright: © 2026 Yelamasetti et al. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability: All data underlying the findings reported in this study are provided in the Supporting Information files S1 accompanying this article. The dataset contains the experimental results for all 18 L18 configurations and the confirmation configuration, together with the parameter settings and response values used for the analyses reported in the manuscript. Funding: The author(s) received no specific funding for this work. Competing interests: The authors have declared that no competing interests exist. Introduction Fused filament fabrication (FFF) is widely used for producing polymer components with complex geometries, comparatively low material waste, and flexible control over internal architecture [ 1 – 5 ]. Its layer-wise manufacturing principle is particularly suitable for lightweight structural design because material distribution can be controlled through geometric modelling and process parameters. Polylactic acid (PLA) is among the most commonly used thermoplastics in FFF because of its processability, availability, and favourable specific mechanical properties [ 6 , 7 ]. However, the mechanical response of FFF-printed PLA components depends on both manufacturing conditions and structural geometry, including material distribution and build-related parameters [ 6 , 7 ]. When the printing conditions are held constant, structural geometry provides a direct means of modifying load-bearing behaviour and material usage. This makes geometric design particularly important when mechanical performance must be improved without an excessive increase in structural mass. Cellular architectures provide an effective means of controlling the mechanical performance and mass of additively manufactured components. Among these architectures, hexagonal honeycomb structures are widely investigated because their response can be tailored through cell size, wall thickness, and face-sheet geometry [ 8 , 9 ]. In a sandwich panel subjected to bending, the face sheets primarily resist normal stresses, whereas the cellular core transfers shear loads and maintains separation between the faces. Consequently, modifications to the core and face-sheet dimensions can alter both the load-bearing behaviour and material requirement of the complete structure. Understanding these coupled effects is essential for the design of lightweight FFF-printed sandwich panels. Previous investigations have established that the mechanical behaviour of additively manufactured cellular structures is sensitive to core topology, geometric dimensions, material distribution, and loading conditions. Montazeri et al. [ 10 ] examined conventional and auxetic 3D-printed honeycombs under three-point bending and demonstrated the influence of structural configuration and internal reinforcement on flexural response. Gajdoš et al. [ 11 ] reported differences in the flexural behaviour of FFF components produced with honeycomb and sparse internal structures, while Bharath et al. [ 12 ] demonstrated the potential of additively manufactured cellular sandwich composites under bending loads. These studies confirm the importance of internal architecture but also show that the mechanical response of cellular structures cannot be considered independently of their geometric design. The utility of honeycomb architectures has also been demonstrated in protective applications, where incorporation of a honeycomb lattice reduced the simulated impact response of an electric-vehicle battery-pack configuration [ 13 ]. Studies focused specifically on polymeric honeycomb sandwich structures have further demonstrated the influence of core and face-sheet parameters. Brischetto and Torre [ 14 ] experimentally examined FFF-printed PLA honeycomb sandwich specimens and reported the dependence of structural response on material and core configuration. Hashemi and Galehdari [ 15 ] investigated functionally graded PLA honeycombs and showed that variations in cellular geometry considerably influence mechanical response and energy absorption. Cojocaru et al. [ 16 ] compared hexagonal, grid, and triangular PLA structures under bending, demonstrating the effects of topology and loading orientation. Antony et al. [ 17 ] examined hemp fibre/PLA honeycomb sandwich panels and demonstrated the potential of reinforced FFF structures for lightweight applications. Experimental design and statistical analysis provide a practical means of separating the effects of multiple design variables without requiring exhaustive testing of every possible parameter combination. Taguchi methods have been applied to cellular and additively manufactured structures to evaluate geometric and manufacturing variables using reduced experimental programmes [ 18 , 19 ]. More recent investigations have addressed the structural optimization and mechanical performance of additively manufactured sandwich systems [ 20 – 22 ]. Recent work has also demonstrated the potential of biomimetic honeycomb architectures for balancing lightweight construction with structural and functional performance, further illustrating the versatility of honeycomb-based designs [ 23 ]. Geramizadeh et al. [ 24 ] specifically examined face-sheet thickness in polymeric honeycomb sandwich beams, demonstrating that face-sheet design can influence bending behaviour and should be considered together with core geometry. Despite these developments, an important design issue remains when flexural performance and structural mass must be considered simultaneously in FFF-printed honeycomb sandwich structures. Previous studies have shown that manufacturing parameters influence the mechanical response of additively manufactured polymers [ 25 – 27 ], while investigations of additively manufactured honeycomb and sandwich structures have demonstrated the importance of core architecture, cellular geometry, and face-sheet configuration [ 28 ]. Optimization studies have further shown the potential of systematic parameter-selection approaches for improving the performance of additively manufactured structures [ 29 , 30 ]. However, the combined effects of honeycomb cell size, cell-wall thickness, and the two face-sheet thicknesses on both flexural strength and total panel mass have received comparatively limited experimental attention within a single design framework. In particular, the factor levels that favour maximum flexural strength need not coincide with those that minimize mass, creating a need for a transparent procedure for selecting a practical compromise configuration. The present study addresses this design requirement by experimentally evaluating four geometric variables-honeycomb cell size (HCS), honeycomb cell-wall thickness (HCT), top face-sheet thickness (TFS), and bottom face-sheet thickness (BFS)-within a mixed-level Taguchi L18 design. ANOM is used to identify the factor levels favoured independently by maximum flexural strength and minimum mass, while ANOVA is used to quantify the relative contribution of each parameter to the two responses. The response-specific factor settings are subsequently combined with the normalized ANOVA contributions to obtain a contribution-weighted compromise configuration, which is then fabricated and experimentally evaluated. The study is therefore intended to answer three design questions: which geometric parameters predominantly control flexural strength and mass; whether the same parameter settings can satisfy the two competing responses; and whether contribution-weighted combination of the response-specific settings can produce a practically useful lightweight configuration. Accordingly, the objectives are to (i) quantify the effects of HCS, HCT, TFS, and BFS on measured flexural strength and panel mass; (ii) determine the statistical contribution and significance of each parameter; (iii) identify and reconcile the conflicting factor settings associated with the two responses; and (iv) experimentally evaluate the resulting compromise configuration. The principal contribution of this work is not the use of Taguchi analysis or ANOVA individually, but the integration of experimentally obtained factor-level trends and response-specific contribution ratios in the selection of a single strength–mass compromise design. This provides a transparent link between experimental sensitivity analysis and subsequent parameter selection while avoiding the assumption that the configuration favoured by either response alone represents a suitable lightweight design. Materials and methods Material and fabrication conditions Commercial polylactic acid (PLA) filament with a nominal diameter of 1.75 mm was used to fabricate all specimens. The PLA filament was manufactured by eSUN. The filament was received directly from the supplier and used as received for printing the honeycomb structures, without any additional drying or reheating treatment. The extrusion temperature, nominal infill density, layer thickness, printing speed, and bed temperature were 210 °C, 100%, 0.2 mm, 30 mm/s, and 55 °C, respectively. The cooling fan was switched off during printing. The wall/perimeter count and extrusion width were not recorded. All panels were printed in a flat orientation, with the bottom face placed directly on the build plate. The longitudinal direction of the panel was aligned with the X-axis of the build platform, while the honeycomb cell walls were built vertically along the Z-axis. This orientation was maintained for all configurations to ensure a common build direction and consistent layer arrangement during comparative evaluation; alternative build orientations were not investigated in the present study. These fabrication conditions were kept unchanged throughout the experimental programme so that the analysis focused on the selected geometric variables. The available records therefore do not permit reconstruction of the complete slicer toolpath settings, although the recorded printing conditions were kept unchanged for all experimental configurations. Specimen geometry and experimental design The honeycomb sandwich panels were modelled using Autodesk Fusion 360 (2024) and exported in stereolithography (STL) format. The models were processed using Simplify3D (Version 5.1) to generate the G-code and were fabricated using a PRATHAM 5.0 FFF machine (MAKE3D.IN) equipped with a 0.4 mm nozzle. Four geometric parameters were investigated: HCS, HCT, TFS, and BFS. HCS and HCT control the geometry and material distribution of the cellular core, whereas TFS and BFS control the material distribution in the face sheets. The 1, 2, and 3 mm TFS and BFS levels represent the nominal face-sheet thicknesses specified in the CAD models rather than prescribed numbers of perimeter lines. The available records do not contain the extrusion-width or perimeter-count settings used during slicing to realize these nominal dimensions. Likewise, the intermediate HCT and TFS dimensions used for the validation configuration are reported as nominal CAD dimensions; no claim is made that the corresponding as-built dimensions were identical to the nominal values. These variables were selected because changes in their dimensions can simultaneously affect load transfer, resistance to deformation, and the quantity of material required for fabrication [ 4 , 10 , 20 – 22 ]. A conventional hexagonal topology was retained for all specimens so that the experimental analysis focused on the selected dimensional variables rather than changes in cellular topology. The investigated parameter levels are given in Table 1 . Download: PNG larger image TIFF original image Table 1. Geometric design parameters and factor levels used in the experimental design. https://doi.org/10.1371/journal.pone.0358969.t001 HCS was investigated at two levels, whereas HCT, TFS, and BFS were each investigated at three levels. A mixed-level L18 Taguchi orthogonal array was therefore selected to organize the experimental programme [ 18 , 19 ]. The design comprised 18 geometric configurations and enabled the effects of the four parameters on flexural strength and mass to be systematically evaluated with a reduced experimental set. One specimen was tested for each of the 18 L18 configurations, and one specimen was tested for the confirmation configuration. The values reported in Table 2 therefore represent individual experimental measurements rather than replicated mean values. The factor combinations and measured responses are presented in Table 2 . Download: PNG larger image TIFF original image Table 2. Taguchi L18 experimental design, specimen dimensions, measured responses, and flexural-strength-to-mass ratio. https://doi.org/10.1371/journal.pone.0358969.t002 Each specimen consisted of a conventional hexagonal honeycomb core integrated with top and bottom face sheets. The overall specimen dimensions resulting from the investigated geometric configurations are reported in Table 2 . The cellular count and topology were kept consistent while HCS was varied; consequently, changing HCS also changed the overall specimen length and, through the fixed nominal span-to-height condition, the support span. Therefore, the HCS contribution should be interpreted as the response of the complete geometric configuration rather than as an isolated cell-size effect. This design feature was considered when interpreting the ANOVA contribution of HCS. As illustrated in Fig 1 , the overall specimen length, width, and height are denoted by TL, TW, and TH, respectively, while HCS and HCT represent the cell size and cell-wall thickness. Download: PNG larger image TIFF original image Fig 1. Geometry and principal dimensions of the honeycomb sandwich panel and hexagonal unit cell. https://doi.org/10.1371/journal.pone.0358969.g001 Measurement of responses Three-point bending tests were conducted with reference to the test arrangement described in ASTM D7249/D7249M-20 using a universal testing machine equipped with a 10 kN load cell [ 31 ]. The approximately 3:1 span-to-height ratio used in the present study was a study-specific comparative condition and was not adopted as a material-level requirement of the standard. The same nominal ratio was maintained across the L18 configurations to provide a common comparative test condition despite differences in specimen height. The specimens were positioned on two supports and loaded centrally, as illustrated in Fig 2 . Because the geometric configurations produced different specimen heights, the support span was adjusted to maintain a nominal span-to-height ratio of approximately 3, as reported in Table 2 . Loading was applied at a constant crosshead displacement rate of 2 mm/min using a cylindrical loading nose with a diameter of 30 mm. The support span was selected to maintain a consistent nominal span-to-height ratio across the different specimen heights. The approximately 3:1 ratio was retained as a common comparative test condition across the different specimen heights rather than being used to establish a material-level flexural property. Because the resulting span-to-height ratio was approximately 3, the measured response may include contributions from core shear and local deformation near the loading and support regions in addition to face-sheet bending. The post-test photographs were used to document the visible deformation of the fabricated panels. Because the available experimental record does not contain a systematic failure-mode classification or close-up measurements of the damaged regions, individual specimens were not assigned to specific failure mechanisms. The mechanical response is therefore discussed in terms of the overall sandwich behaviour and the possible contributions of core deformation and local loading-region effects. Accordingly, the reported value is interpreted as the nominal flexural response of the complete sandwich configuration under the specified three-point bending arrangement rather than as a pure material property. The selected span-to-height ratio was applied consistently across the experimental configurations for comparative evaluation and was not intended to establish a material-level flexural property. The load–displacement response was recorded during each test, and the maximum load was used to obtain the reported nominal flexural-strength response. The original calculation sheet containing the individual maximum-load values and the exact flexural-strength calculation expression was not available among the experimental records accessible for this revision. Consequently, the individual maximum-load values and the original calculation e
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