DETAILED ACTION
Response to Amendment
Applicant's amendment filed January 30th, 2026 has been entered. Claims 1 and 17 have been amended.
The Section 103 rejections made in the Office action mailed November 3rd, 2025 have been reapplied due to Applicant’s amendments.
Response to Arguments
Applicant's arguments filed January 30th, 2026 have been fully considered but they are not persuasive.
Applicant argues that no reference teaches the use of tow value in relation to a diameter of the apertures such that the volume fraction is greater than about 50 vol%. The Examiner disagrees.
Each of the main references Stanley, Wu, and especially Roth teach the desire for increased volume fraction:
Stanley teaches two types of panels comprising NASA panels that are not pre-punched and Utah panels that are pre-punched [pg. 9], wherein the NASA process is specifically criticized for increasing the diameter of the hole in relation to the thread due to the increased resin occupying the hole [pg. 13].
While Wu (now only an optional reference) only demonstrates examples comprising 6 vol% fiber content in the holes, this is merely because this aspect was not being tested, but Wu also teaches that a higher fiber volume fraction also facilitates the resin infusion process, and is desirable.
Roth (now not an optional reference) explicitly teaches that column diameter is improved when it is corresponding to rather than dependent on the cross-sectional area of the fiber thread, wherein the hole is pre-punched so as to not be expanded in relation to the fiber diameter/cross-sectional area, due to expansion during needle insertion during any multiple insertion/insertion-removal process that extends through the entire thickness of the composite [0006, 0010-0014], wherein the multiplicity of fibers/filaments in the bundles/threads provides diameters of the reinforcing structure from 0.1 mm to 2.0 mm, which is a result effective variable with the tow value (number of fibers/filaments in the thread) which is set to substantially match the hole diameter such that the fiber volume content in the holes is greater than 50% [0014, 0038, 0040]. Roth also teaches the core thickness is 1 to 150 mm and the outer layers are 0.1 to 5.0 mm, giving an overall thickness range of 1.2 to 160 mm, which is prima facie obvious overlapping with the claimed range, wherein Wu motivates increased thickness to increase the strength of the composite.
While Applicant is technically correct in that no explicit relative diameter and tow value selection is made, one of ordinary skill in the art at the time of invention understanding these techniques could have selected a thread tow value/diameter/denier in relation to the hole diameter in order to optimize the already desired high fiber volume fraction. As related to the method claims, “selected” is not an active step and could be met inherently by one of ordinary skill in the art looking to optimize fiber volume fraction within the holes.
Claim Objections
Regarding claims 3, 9, and 13, the terms “a thickness” of claim 3 and “a diameter” of claim 9, and “a tow value” of claim 13 have already been set forth in claim 1 and should be identified with “the”.
Claim Rejections - 35 USC § 103
Claims 1-12 & 15-20 are rejected under 35 U.S.C. 103 as being unpatentable over Stanley et al. (Development and Evaluation of Stitched Sandwich Panels) (hereinafter “Stanley”), as evidenced by or in view of Potluri et al. (Novel stitch-bonded sandwich composite structures), and (further) in view of Roth (U.S. Pub. No. 2010/0209658 A1) (hereinafter “Roth”) and optionally Wu et al. (Flexural performance of integrated 3D composite sandwich structures) (hereinafter “Wu”).
Regarding claims 1-3, 6-8, 10, 12, 15-19, Stanley teaches a composite sandwich structure comprising upper and lower facesheets sandwiching a lightweight core layer, generally a carbon fiber facesheet and a foam stitched together by Kevlar yarns infiltrated with epoxy resin by vacuum assisted resin transfer molding [pgs. 2-3], with experimental examples comprising a polyurethane closed-cell foam and carbon fiber woven twill performs [pgs. 8-10] infiltrated with epoxy, wherein the core and facesheets comprise through holes punched therein using the threading needle for NASA panels and by needle and/or CNC-milling machine for Utah panels to achieve straight accurately placed stitches followed by stitching at periodic intervals using a modified lock stitching process, wherein a continuous reinforcing upper thread is passed twice through the preformed holes forming a loop at the lower surface which is then intersected (interlocked) by/with a lower/bobbin thread [pgs. 9-11], wherein Potluri evidences/teaches that a modified lock stitch process for a composite sandwich structure on a commercial machine comprises the upper continuous looping/stitching thread and the lower bobbin/locking thread is inserted by a pneumatically operated (back and forth) rapier that behaves as a continuous weft yarn [pg. 253-254, 3.-3.2], wherein it would have been obvious to and motivated for one of ordinary skill in the art at the time of invention that if the bobbin thread were not already treated as a continuous weft yarn to provide a continuous weft yarn similar/identical to or as adapted for a commercialized process, which is the followed by the resin infiltration process that creates resin columns extending through the holes, wherein Stanley further teaches that when forming the NASA panels using the process of needle punching to form the stitch holes, it has been found that extra resin in the columns surrounding the stitch is undesirable since it increases the weight of the panel without providing significant additional reinforcement to the foam core [pg. 13], such that using the Utah process to optimize a volume fraction of continuous reinforcing stitching thread providing the reinforcing thread with a majority of the volumetric capacity of the hole would be desirable. Also, Stanley teaches the Kevlar thread used for upper stitch yarns is 1600 denier [pg. 10], which is approximately 0.4 to 0.45 mm diameter, and it is indicated that 0.05 in (1.27 mm) diameter needles are preferably used to form holes, but it is unclear if the formed hole diameter is related to the pre-punched Utah panels.
Regarding claims 1-2, the fiber volume fraction within each hole being greater than 50 vol% due to the selected tow value of the stitching yarn/thread relation to the diameter of the hole is not taught.
Roth teaches a fiber reinforced sandwich structure comprising a core layer of felt or foam, and a first and second opposing outer layers comprising a textile layer such as nylon, polyester, metal, aramid, carbon, or glass fibers and other reinforcing materials [0036], wherein the sandwich structure is perforated in any pattern or angular position prior to the insertion of a lock-stitched sewing thread [0016, 0034], which is improved over perforation during any stitching that requires multiple insertions/insertion-removal [0005-0006, 0013-0014], wherein the stitching thread comprises a multifilament bundle/twist (having an inherent tow value) of reinforcing fibers comprising a typical diameter of 0.1 mm to about 2.0 mm with the through-hole diameter corresponding to but not reliant upon such that the fiber volume content is above 50% [0014-0015, 0034, 0038, 0040].
It would have been obvious to one of ordinary skill in the art at the time of invention to provide core with a plurality of apertures prior to providing a continuous reinforcing yarn. One of ordinary skill in the art would have been motivated to prevent the enlarging of a core thread hole such that it increases the fiber volume content therein to acceptable/optimized levels, already desired by Stanley, and also provides good (hole) alignment, already desired by Stanley, and no sandwich buckling [0006, 0010-0011, 0013-0015, 0034, 0040].
Further regarding claims 1 and 3 and regarding claim 4, a core thickness is provided in experimental examples to be 0.5 or 1.0 inch (about 13 mm and about 25 mm), but an overall thickness and/or facesheet thickness within the claimed ranges is not taught.
Roth teaches that a core material comprises a thickness of 1 to 150 mm and facesheets comprising a thickness of 0.1 to 5.0 mm, giving an overall thickness of 1.2 mm to 160 mm, wherein when the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05 I.
In the event that a total composite panel thickness of greater than 30 mm is not properly motivated: Wu teaches a composite sandwich structure, wherein structural parameters have a significant influence on flexural properties, especially the thickness of the facesheet(s) and the core [Abstract], wherein facesheet thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm are used with increasing flexural stiffness corresponding to increasing facesheet thickness and foam core thickness of 29 mm, 30 mm, 31 mm, 32 mm, and 33 mm are used with increasing flexural stiffness corresponding to increasing foam core thickness (pg. 1504), for possible total thicknesses ranging from 31 mm to 39 mm.
It would have been obvious to one of ordinary skill in the art at the time of invention to provide a total sandwich thickness, facesheet thickness, and core thickness optimizably near or within one of the claimed values. One of ordinary skill in the art would have been motivated to provide known exemplary values [Roth], wherein a sandwich composite with increased facesheet, core, and total thicknesses to increase flexural stiffness [Wu], wherein one of ordinary skill would have understood how to properly balance increased flexural strength with other factors such as desired use, cost of materials, and added weight.
Regarding claim 9, Stanley teaches that the holes punched in the composite are formed at 0.09 inch (about 2 mm) and preferably 0.05 inch (about 1 mm) [pg. 13]. Furthermore, Roth teaches/makes obvious a typical diameter of a pre-punched reinforcing structure to be about 0.1 mm to 2.0 mm [0038]. Also, Wu teaches/makes obvious that while higher column diameters might increase flexural stiffness, they also increase column crack likelihood and thus decreases peak load (pg. 1504). Therefore, one of ordinary skill in the art would have been motivated to use a hole diameter as one of the claimed values to minimize excess resin within the columns [Stanley], using a typical value [Roth], that minimizes column cracking [Wu], each reference further teaching that increased fiber volume fraction increases strength.
Regarding claim 11, the stitch holes were placed at half-inch intervals between stitches and half-inch spacing between stitch rows [pg. 9], such that an estimated areal density, depending on how one counts the stitches (1 to 4 per unit area), is about 0.6 to about 2 per square density
Regarding claim 20, Stanley teaches the vacuum assisted resin transfer molding process comprises degassing the (epoxy) resin, infiltrating/infusing the resin in a sealed vacuum bag, and curing the resin (pg. 23), wherein the sealed vacuum bag also comprises a breather cloth to absorb excess resin and to allow gasses to exit (degas) (pg. 14).
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Stanley in view of Roth and optionally Potluri and/or Wu, as applied to claim 1 above, (even) further in view of Maheshwari (U.S. Pub. No. 2010/0196654 A1) (hereinafter “Maheshwari”) OR Weber et al. (U.S. Pub. No. 2009/0252917 A1) (hereinafter “Weber”).
Regarding claim 13, Maheshwari teaches a closed cell core between resin-impregnated fabric layers that are stitched together by a roving [Abstract] that can be formed of graphite (carbon), glass, or polymer such Kevlar, wherein the roving can comprise any number of continuous fibers, preferably at least 3000 (3K) filaments and as many as 12,000 (12K) filaments such as in the case of a graphite roving [0025].
OR
Weber teaches reinforcing a cellular-core sandwich construction for aircraft structures, wherein the reinforcing fiber bundle comprises a loopable reinforcing bundle, which may be made of aramid (Kevlar), carbon, nylon, polyester, metal, or glass fibers, frequently consisting of 12K rovings, wherein it is possible to use rovings with more or less filaments, such as 24K rovings [0016, 0044].
It would have been obvious to one of ordinary skill in the art at the time of invention to provide a reinforcing thread for a sandwich construction as comprising a tow value within the claimed range. One of ordinary skill in the art would have been motivated to provide a preferable [Maheshwari] or consistently used [Weber] tow value for the same feature of a stitching yarn for forming stitched sandwich composites.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the Examiner should be directed to JEFFREY A VONCH whose telephone number is (571)270-1134. The Examiner can normally be reached M-F 9:30-6:00.
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If attempts to reach the Examiner by telephone are unsuccessful, the Examiner’s supervisor, Frank J Vineis can be reached at (571)270-1547. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/JEFFREY A VONCH/Primary Examiner, Art Unit 1781 February 20th, 2026