Interlocking Pattern Research Articles

The Pucok Reubong Motif as an Inspiration for Leather Bag Design

The pucok reubong motif has been stylised from the form of young bamboo shoots. These bamboo shoots are transformed into a unique decorative pattern. The artist's interest in exploring the pucok reubong motif stems from its distinct shape, surrounded by triangular leaves with pointed ends resembling swords, and its interlocking patterns. This inspired the artist to incorporate the pucok reubong motif into leather bag designs. The creative process follows the Hendriyana method, which consists of four main stages: (1) pre-design, which involves the development of imagination; (2) design, where alternative designs are visually conceptualized; (3) realization, in which selected sketches are transformed into final works; and (4) presentation, involving exhibitions to establish communication between the artist and art enthusiasts. The concept applied is a symbolic expression, representing modern art that utilizes traditional idioms as its foundation. In the final project titled “Pucok Reubong Motif as an Idea for Leather Bag Creation”, the artist applied the pucok reubong motif as a decorative element on leather bags. This work aims to enhance aesthetic appeal while introducing the pucok reubong motif to a wider audience unfamiliar with it. The bags were created using embossing techniques combined with weaving, resulting in works that are both artistic and meaningful.

Mechanical properties and failure mechanisms of 3D layer‐to‐layer interlock woven composites

AbstractThree‐dimensional layer‐to‐layer interlock woven composites (3D LTLIWCs) have been widely used in various aero‐engine blade models because of their excellent near‐net forming capabilities for complex components, as well as significant advantages in structural design flexibility and high damage tolerance. In this paper, a typical and two new 3D LTLIWCs, specifically including 1/3 twill (S‐I), modified satin (S‐II), and stuffer twill (S‐III), were manufactured by two design methods: varying interweaving frequency and introducing stuffer yarns. Three‐point bending and uniaxial tensile tests were conducted along the 0° (warp) and 90° (weft) directions. The damage morphology and failure mechanism of the specimens were revealed by nondestructive testing technology and topological structure analysis. The results showed that the fabric structure significantly influenced the mechanical properties and failure mechanisms of the 3D LTLIWCs. Compared with S‐I and S‐II, S‐III demonstrated a 17.9%–80.2% increase in bending strength and a 35.3%–162.8% increase in tensile strength in the 0° direction, while the bending strength and tensile strength in the 90° direction increased by 1.1%–73.3% and 9.3%–50.4%, respectively. Notably, S‐III exhibited lower bending and tensile damage in the 0° direction than S‐I and S‐II, with a smaller propagation range of resin and interface cracks and less severe shear fracture of the load‐bearing yarns. This study can provide a useful reference for the optimal design of fabric structure for 3D woven composite blades.Highlights Two design schemes for optimizing 3D LTLI fabric structure were compared. Introducing stuffer yarns improved the mechanical properties of 3D LTLIWCs. S‐III composites exhibited the highest failure strength in all test directions. Full‐field strain distribution was closely related to the interlocking patterns. Fabric structures had a great influence on the failure modes of 3D LTLIWCs.

Paper 51: A Radiostereometric Analysis of Tendon Migration following Arthroscopic and Mini-Open Biceps Tenodesis: Interference Screw confers Greater Construct Stability than All-Suture Suture Anchor Fixation, with No Difference in Patient-Reported Outcomes

Objectives: To quantify the postoperative migration of the BT construct between arthroscopic suprapectoral (ASPBT) and open subpectoral (OSPBT) techniques via interference screw (IS) or all-suture anchor with a single suture (SSSA) fixation with radiostereometric analysis (RSA). Methods: Distal migration of the biceps tendon following OSPBT with a Polyetheretherketone (PEEK) IS, OSPBT with one SSSA, ASPBT with PEEK IS, and ASPBT with two SSSAs was measured prospectively. Patients with symptomatic biceps tendinopathy and preoperative Patient-Reported Outcome Measures (PROMs) including CMS, SANE, or PROMIS-UE scores were included. A tantalum bead was sutured on the proximal end of the long head biceps tendon before fixation. AP radiographs were performed immediately postoperatively, 1 week, and 3 months. Bead migration was measured, and PROMs were compared. Results: Of 115 patients, 94 were available for final follow-up (82%). Average age was 52.1±10.5 years, and BMI was 30.8±5.4 kg/m2. There was no difference in tendon migration between OSPBT and ASPBT performed with an IS (P=0.70). OSPBT performed with one SSSA (21.70 mm) demonstrated significantly greater migration than ASPBT with IS (4.31mm, P<0.001) and OSPBT with IS (5.04 mm, P<0.001). Three patients (9.4%) who had OSPBT with one SSSA and one who had ASPBT with two SSSAs (3.8%), developed a Popeye deformity; none occurred in the IS groups. Mean 12-week bead migration in patients with versus without Popeye deformity was 60.8 mm and 11.2 mm, respectively (P<0.0001). PROMs did not differ at final follow-up. Conclusions: ASPBT and OSPBT with IS fixation demonstrated the least tendon migration, while OSPBT with one SSSA yielded the most. Compared to IS, fixation with one, but not two, SSSAs resulted in significantly greater migration. Average bead migration following a Popeye deformity was 6.1cm. To minimize migration when using SSSAs, at least 2 sutures should be used with an interlocking pattern within the tendon. [Table: see text]

Bowl: Anyam Technique on Ceramic

Adding value to works of art is the subject of many discussions, and finding a new aesthetic can be accomplished by innovation and experimenting with the medium and techniques employed. This research attempts to make ceramics utilizing various embodied approaches similar to other manufactured materials. Specifically, bowl-shaped ceramics are formed using a woven technique similar to bamboo and then arranged in an interlocking pattern to resemble woven bamboo. The final result of this application technique is in the form of artistic bowls that have afresh aesthetic value for the development of ceramic art. These bowls are hollow due to the woven fabric and contain many values built-in to ceramic form, including material efficiency, organic form, and artistic form, which was previously unexpected. This serves as an accelerator for future application development of various shaping approaches. This confirms that the creative possibilities for plastic clay are virtually endless.

Additively Manufactured Dual-Faced Structured Fabric for Shape-Adaptive Protection.

Fabric-based materials have demonstrated promise for high-performance wearable applications but are currently restricted by their deficient mechanical properties. Here, this work leverages the design freedom offered by additive manufacturing and a novel interlocking pattern to for the first time fabricate a dual-faced chain mail structure consisting of 3D re-entrant unit cells. The flexible structured fabric demonstrates high specific energy absorption and specific strength of up to 1530 Jkg-1 and 5900 Nmkg-1 , respectively, together with an excellent recovery ratio of ≈80%, thereby overcoming the strength-recoverability trade-off. The designed dual-faced structured fabric compares favorably against a wide range of materials proposed for wearable applications, attributed to the synergetic strengthening of the energy-absorbing re-entrant unit cells and their unique topological interlocking. This work advocates the combined design of energy-absorbing unit cells and their interlocking to extend the application prospects of fabric-based materials to shape-adaptive protection.

Exploring the Binding Capacity of Mycelium and Wood-Based Composites for Use in Construction.

Existing research on mycelium-based materials recognizes the binding capacity of fungal hyphae. Fungal hyphae digest and bond to the surface of the substrate, form entangled networks, and enhance the mechanical strength of mycelium-based composites. This investigation was driven by the results of an ongoing project, where we attempt to provide basic concepts for a broad application of a mycelium and chipped wood composite for building components. Simultaneously, we further explore the binding capacity of mycelium and chipped wood composites with a series of experiments involving different mechanical interlocking patterns. Although the matrix material was analyzed on a micro-scale, the samples were developed on a meso-scale to enhance the bonding surface. The meso-scale allows exploring the potential of the bio-based material for use in novel construction systems. The outcome of this study provides a better understanding of the material and geometrical features of mycelium-based building elements.

Placed Riprap Deformation Related to Axial Load at Toe Support: Physical Modelling

Rockfill dams are hydraulic structures of major importance. They can be exposed to extreme flood events, in turn leading to overtopping. These phenomena erode and affect structural and geotechnical integrity, which in turn can cause dam breach. Ripraps are broadly used for rockfill dam protection against such erosion processes. For steep slopes, as the one considered in this study (S = 1:1.5, vertical: horizontal), understanding the riprap behavior during overtopping is an important issue to improve dam design and reinforcement techniques. In this work, datasets are obtained from five experimental models of placed riprap built on a rock filter layer in a flume, at the hydraulic laboratory of the Norwegian University of Science and Technology, Trondheim. The riprap stones were placed in an interlocking pattern with a metallic support at the toe. The models were subjected to successive and incremental overtopping discharges until their complete failure. A laser traverse system was used to measure the coordinates (3D) of individual marked riprap stones between each discharge increase. Six load cells located at the toe measured the imposed loads during the entire procedure. From the total load values, two different types of load contributions could be distinguished: the self-weight of the stones and the hydraulic load depending on the discharge level of the overflow. This article highlights the strong relation in each of the five tests between riprap stone displacements, axial reaction load values measured at the toe and overtopping discharges. Moreover, as demonstrated in previous works, a buckling deformation of the riprap layer was observed and described. The results demonstrate that as the hydraulic load induces 2D deformations of the riprap, a larger part of the riprap weight is supported at the toe. Thus, the measured axial load during overtopping arises both from the hydraulic load and from the load imparted due to the compaction of the riprap layer. This compaction effect induces an even greater load than the one imposed due to the hydraulic contribution. The results from this study are finally put into perspective with the Norwegian Water Resources and Energy Directorate recommendations for full scale dams and suggest the great resistance of supported riprap at the toe.

Impact Performance of Three-dimensional Woven Composites with Novel Binding Yarn Patterns

ABSTRACT This research offered an experimental examination of the effect of binder yarns, and 3D woven patterns on impact (Charpy and drop weight impact), and compression after impact (CAI) performance of seven (07) different kinds of 3D woven jute/green epoxy composites. Along with four (04) typical classifications of 3D woven reinforcements i.e., OLL, OTT, ALL, ATT, and three (03) novel (hybrid) 3D reinforcements i.e., H1 (OTT and ATT interlocking pattern), H2 (OTT and ALL interlocking pattern), H3 (OLL warp and weft interlocks “bidirectional”) were also developed on dobby weaving machine. OTT composite displayed the highest amount of impact strength during Charpy impact in both in-plane directions i.e., warp and weft in comparison with others due to the existence of the truly vertical binder yarns which is comparable with H1. While ALL sample exhibited the highest value of maximum load, work done, and energy absorbed during the 3 J and 6 J drop weight impact energies which is nearest comparable with hybrid 3 (H3) composite. H3 composite sample revealed the highest value of compression after impact (CAI) stress and modulus in both energy levels due to the presence of both warp and weft binder yarns in a single 3D structure.

Flutter performance of shape memory alloy-embedded 3D woven flexible composite plate under subsonic flow

Recently, 3D composites have gained prominence over 2D composites due to their remarkable through-the-thickness reinforcement that enhanced performances of structures subject to multi-directional stress conditions. However, it is at the expense of reduced in-plane properties. 3D composites also increased damage tolerance due to their high impact and delamination resistance properties, which are susceptible in 2D composites. In aeronautics, both are major concerns in primary structures such as lifting and control surfaces due to high vibrational loads from the airflow. Advancements in the aeroelasticity of aircraft structures show an increasing trend in using smart materials with composite structures for improved aeroelastic performance. An example is combining shape memory alloys (SMAs) with composites for improving damping, stiffness, and vibrational characteristics by utilizing stress generation and strain accommodation properties of SMAs in response to temperature and load, respectively. Published works are mostly numerical in nature, and experimental research is noticeably lacking as aeroelasticity is multidisciplinary and involves both structural and aerodynamic methodology. In this work, 3D composites with embedded SMA wires (for improved in-plane properties) are evaluated in terms of flutter performance in wind tunnel flutter testing under low airspeed conditions. Three 3D orthogonal interlock configurations with a different interlocking pattern of yarns with SMA wire were considered. These 3D configurations are layer-to-layer (L2L), through-the-thickness (TT), and a modified interlock (MF) structure that provides the strongest grip to SMA wire than L2L and TT. The effect of SMA positioning, at mid and near to trailing and leading edges of the cantilevered composite plate, on the aeroelastic flutter properties is also investigated. Results showed that activating SMA wires embedded in 3D structures have significantly improved post-flutter properties while there is a decrement in flutter speed and flutter frequency due to increased flexibility of deflected plate in the airflow by SMA-induced stresses. Among 3D structures, L2L with SMA near to trailing edge showed significant improvement in post-flutter properties by decreasing 22.2% in twist limit cycle oscillation (LCO) amplitude while L2L with SMA at mid showed a decrement of 9.5% for bending LCO amplitude. Hence, this work showed that embedding SMA is beneficial for mitigating the post-flutter vibrations but at the consequence of reduced flutter speed and frequency of flexible composite plate.

Improving single-lap joint load bearing by bioinspired interlocking patterns on substrates

This study aims to evaluate the effect of adding a pattern of conical holes on the substrate surface to improve mechanical interlocking of the bonded joint. The holes allowed the formation of micro pillars in the adhesive layer, promoting mechanical interlocking and considerably increasing the resistance of the joints. The single-lap shear tests were performed according to the ASTM D1002 standard. The results showed that the proposed solution presents a viable alternative to improve the resistance of bonded joints, promoting an increase of up to 99.84% in the final displacement and final resistance of the tested specimens. The finite element analysis also showed a reduction up to 18.11% in the stress peaks in the singularity point of the adhesive layer. Significant changes in the stress distribution around the micro pillars also was observed. Failures also have changed from an almost entirely adhesive condition to extremely fragmented cohesive failures.

Study on the Viability of Canine Nose Pattern as a Unique Biometric Marker.

Simple SummaryThis paper shows that the canine nose pattern, which is an interlocking pattern of beads and grooves on a dog’s nose, is unique to each individual dog. For this purpose, the nose images of 60 dogs were collected at three separate times, each roughly three to four months apart. This longitudinal cohort study was designed to ensure the diversity of data, wherein dogs of diverse age, gender, and breed are well represented in the dataset. In this study, the nose patterns of these dogs were examined visually and by a biometric algorithm to determine the uniqueness of the canine nose pattern. It was found that the canine nose pattern remains invariant through the passage of time during the observation period; and that the canine nose pattern is indeed unique to each dog. Our finding confirms and enhances the claims of earlier works by others that the canine nose pattern is unique to each animal and serves as a unique biometric marker. For further study, this dataset was augmented by adding to it the nose images of 10 beagle dogs taken once every month in a ten-month period to create an enlarged dataset of 278 images of 70 dogs of 19 breeds. The study with this enlarged dataset also leads to the same conclusion.The uniqueness of the canine nose pattern was studied. A total of 180 nose images of 60 dogs of diverse age, gender, and breed were collected. The canine nose patterns in these images were examined visually and by a biometric algorithm. It was found that the canine nose pattern remains invariant regardless of when the image is taken; and that the canine nose pattern is indeed unique to each dog. The same study was also performed on an enlarged dataset of 278 nose images of 70 dogs of 19 breeds. The study of the enlarged dataset also leads to the same conclusion. The result of this paper confirms and enhances the claims of earlier works by others that the canine nose pattern is indeed unique to each animal and serves as a unique biometric marker.

Establishing the ground squirrel as a superb model for retinal ganglion cell disorders and optic neuropathies

Retinal ganglion cell (RGC) death occurs after optic nerve injury due to acute trauma or chronic degenerative conditions such as optic neuropathies (e.g., glaucoma). Currently, there are no effective therapies to prevent permanent vision loss resulting from RGC death, underlining the need for research on the pathogenesis of RGC disorders. Modeling human RGC/optic nerve diseases in non-human primates is ideal because of their similarity to humans, but has practical limitations including high cost and ethical considerations. In addition, many retinal degenerative disorders are age-related making the study in primate models prohibitively slow. For these reasons, mice and rats are commonly used to model RGC injuries. However, as nocturnal mammals, these rodents have retinal structures that differ from primates - possessing less than one-tenth of the RGCs found in the primate retina. Here we report the diurnal thirteen-lined ground squirrel (TLGS) as an alternative model. Compared to other rodent models, the number and distribution of RGCs in the TLGS retina are closer to primates. The TLGS retina possesses ~600,000 RGCs with the highest density along the equatorial retina matching the location of the highest cone density (visual streak). TLGS and primate retinas also share a similar interlocking pattern between RGC axons and astrocyte processes in the retina nerve fiber layer (RNFL). In addition, using TLGS we establish a new partial optic nerve injury model that precisely controls the extent of injury while sparing a portion of the retina as an ideal internal control for investigating the pathophysiology of axon degeneration and RGC death. Moreover, in vivo optical coherence tomography (OCT) imaging and ex vivo microscopic examinations of the retina in optic nerve injured TLGS confirm RGC loss precedes proximal axon degeneration, recapitulating human pathology. Thus, the TLGS retina is an excellent model, for translational research in neurodegeneration and therapeutic neuroprotection.This study characterizes the composition of the retinal ganglion cell (RGC) layer and the distribution of RGCs in the cone-dominant ground squirrel retina. The RGC density and the anatomical features of axon-astrocyte interaction in the ground squirrel resemble primates, rendering it an excellent alternative model for RGC neurodegeneration and neuroprotection.

Mechanical performance of 3D woven jute/green epoxy composites with novel weaving patterns

Green composites have ecofriendly features that are technically and economically feasible while minimizing the pollution. It refers to the combination of degradable fibers mostly cellulosic materials and natural resins to develop green composites. Since mechanical performance of such structures is a concern for industry, by playing with the position and pattern of yarns in woven fabric, these properties can be optimized. This research focuses on the development and characterization of novel 3D woven jute/green epoxy composites having hybrid interlocking patterns. Four conventional derivatives of 3D woven fabrics i.e. orthogonal layer to layer (OLL), orthogonal through thickness (OTT), angle interlock layer to layer (ALL), angle interlock through thickness (ATT) and three novel 3D woven fabrics i.e. H1 (combination of OTT and ATT binder yarns), H2 (combination of OTT and ALL binder yarns), H3 (combination of orthogonal layer to layer warp and weft interlock called as bi-directional interlock) were developed using different binding patterns on dobby loom. Tensile, flexural, and short beam shear tests were performed to check the mechanical performance of the developed composites. OTT composite structure showed the highest values of tensile strength, modulus, and maximum force both in warp and weft directions as compared to the other 3D interlock structures, due to least interlacement/crimp of binder yarn. While ATT composite exhibited the highest value of flexural strength and modulus both in warp and weft directions due to through thickness angle binder yarns. H3 composite showed the highest values of force and short beam shear strength in warp direction.

Mechanical and Electrical Properties of Elastic-Porous Composite with Cu-Steel Bimetallic Wire Mesh

An elastic-porous composite with Cu-steel bimetallic wire mesh was proposed to meet the requirements of damping, vibration reduction, and electrical conductivity of aerospace hardware equipment. Firstly, the samples with different weight ratios (Cu/steel) were prepared through special manufacturing processes: composite wire preparing, helical coil encircling, stretching with equal pitch, entangling in an interlocked pattern, and cold stamping. Secondly, the mechanical performances such as stiffness, loss factor, and tangent modulus were characterized by the static compression test. Thirdly, the sensitivity of electrical conductivity to the loading force was examined by mechanical-electrical coupling tests. Finally, the influence of the weight ratio (Cu/steel) on the mechanical and electrical properties was discussed. The results show that the Cu elements can generally improve the damping capacity and reduce the stiffness of the material. The resistance-force curves of specimens show obvious nonlinearity, and the resistance decreases with the increase of compression force. The conductivity of the materials increases with the increasing stiffness and weight ratio according to the resistance-stiffness curves.

Behavior of Square Columns with Interlocking Pattern Ties under Axial Compression

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Properties and characterization of novel 3D jute reinforced natural fibre aluminium laminates

Fibre metal laminates (FML) are being used in automotive, aerospace and naval applications due to their light weight and superior performance. The FMLs are made by sandwiching composite with metal. The environmental concerns due to non-biodegradability of such structures, lead to the development of FML containing natural fibre composites. Natural fibres composite, despite having good damping properties have overall poor mechanical properties. However, this aspect can be improved by weaving the fibres in 3 D pattern. In literature, FML made using 3 D woven jute composites is never reported. Furthermore, no literature is found on adhesion of natural fibre composite-metal bonding. In this paper, development of novel 3 D Jute Reinforced natural fibre Aluminium Laminates (JuRALs) is reported. Furthermore, the effect of 3 D weaving pattern and metal-composite bonding on mechanical properties and failure mechanism of the developed samples is also discussed in detail. The four-layered 3 D woven Jute fabric reinforcement was made using four interlocking patterns. The composites and JuRALs were fabricated using epoxy resin by vacuum infusion technique. The surface of aluminium was treated using phosphoric acid anodizing. Tensile, flexural and T-peel tests were performed according to ASTM testing method using Z100 All-round, Zwick Roell. The results showed that out of four types of used reinforcements, the through-thickness composites had better tensile properties while layer-to-layer composite had better flexural properties. The tensile and flexural properties of JuRALs made with through-thickness interlock reinforcement were better as compared to layer-to-layer interlock reinforcement. The T-peel results depicted that the constituent materials influenced the metal-composite adhesion properties, rather the type of 3 D structure.

Fracture Analysis of Rocks for Slope Stability Assessment in SiriKot Area, District Haripur, Khyber Pakhtunkhwa, Pakistan

The landslides are common and hazardous the Northern Gandghar Ranges, Pakistan. The slope failures have affected road sections between Ghazi to Sari area (~65 Km) along the Sirikot road in district Haripur, Pakistan. The objectives consist of failure mechanisms, slope sensitivity and remedial measures in potentially unstable. To analyze slope stability and understand failure mechanisms, Inventory Circle Method (ICM) has been employed at six locations. Most of the landslides have been found in the Precambrian metamorphic Manki Formation, consisting of slate, phyllite and schists. The data acquired through ICM technique have been used to measure the density of fractures and hydraulic properties (porosity and permeability). The fracture analysis revealed two episodes of deformation. Rose and pole diagrams were plotted for stress analysis and fracture orientation to determine the direction of principal stress σ1. Geological Strength Index (GSI) also provided details about the interlocking pattern of the rocks. Topple and rock fall were found in the limestone and quartzite. Moreover, the fractures also provided channels for the water to flow through and penetrate the foliation planes, decreasing the friction and causing a landslide.

Mineralogical Characterization for Selection of Possible Beneficiation Route for Low-Grade Lead–Zinc Ore of Rampura Agucha, India

Mineralogical and morphological characterization of a low-grade lead–zinc ore is carried out prior to the selection of beneficiation strategy using the combination of XRD, XRF, SEM, EPMA, microscopic, and liberation studies. Mineralogical studies indicate that the ore primarily consists of base metal sulfides (galena and sphalerite), ferruginous mineral (pyrrhotite), silicate minerals (quartz, mica, and feldspar), and graphite. Lead–zinc grains are mostly present in an interlocked state with silicate and other sulfide minerals. The sample shows an assay value of 12.14% Zn, 1.77% Pb, 57.6% ISM, 6.47% Fe, 4.19% C, and 40 ppm Ag. Based on the liberation studies, it can be predicted that beneficiation may be opted at − 75 µm as 85% liberation of value minerals is envisaged at this size range. As the ore exhibits high interlocking pattern with low-grade valuable minerals, pre-concentration is necessitated prior to flotation for further downstream operation.

Atomically resolved Au52Cu72(SR)55 nanoalloy reveals Marks decahedron truncation and Penrose tiling surface

Gold-copper alloys have rich forms. Here we report an atomically resolved [Au52Cu72(p-MBT)55]+Cl− nanoalloy (p-MBT = SPh-p-CH3). This nanoalloy exhibits unusual structural patterns. First, two Cu atoms are located in the inner 7-atom decahedral kernel (M7, M = Au/Cu). The M7 kernel is then enclosed by a second shell of homogold (Au47), giving rise to a two-shelled M54 (i.e. Au52Cu2) full decahedron. A comparison of the non-truncated M54 decahedron with the truncated homogold Au49 kernel in similar-sized gold nanoparticles provides for the first time an explanation for Marks decahedron truncation. Second, a Cu70(SR)55 exterior cage resembling a 3D Penrose tiling protects the M54 decahedral kernel. Compared to the discrete staple motifs in gold:thiolate nanoparticles, the Cu-thiolate surface of Au52Cu72 forms an extended cage. The Cu-SR Penrose tiling retains the M54 kernel’s high symmetry (D5h). Third, interparticle interactions in the assembly are closely related to the symmetry of the particle, and a “quadruple-gear-like” interlocking pattern is observed.

Mechanics unlocks the morphogenetic puzzle of interlocking bivalved shells

Brachiopods and mollusks are 2 shell-bearing phyla that diverged from a common shell-less ancestor more than 540 million years ago. Brachiopods and bivalve mollusks have also convergently evolved a bivalved shell that displays an apparently mundane, yet striking feature from a developmental point of view: When the shell is closed, the 2 valve edges meet each other in a commissure that forms a continuum with no gaps or overlaps despite the fact that each valve, secreted by 2 mantle lobes, may present antisymmetric ornamental patterns of varying regularity and size. Interlocking is maintained throughout the entirety of development, even when the shell edge exhibits significant irregularity due to injury or other environmental influences, which suggests a dynamic physical process of pattern formation that cannot be genetically specified. Here, we derive a mathematical framework, based on the physics of shell growth, to explain how this interlocking pattern is created and regulated by mechanical instabilities. By close consideration of the geometry and mechanics of 2 lobes of the mantle, constrained both by the rigid shell that they secrete and by each other, we uncover the mechanistic basis for the interlocking pattern. Our modeling framework recovers and explains a large diversity of shell forms and highlights how parametric variations in the growth process result in morphological variation. Beyond the basic interlocking mechanism, we also consider the intricate and striking multiscale-patterned edge in certain brachiopods. We show that this pattern can be explained as a secondary instability that matches morphological trends and data.