Shape Imperfections Research Articles

The application of novel shear deformation theory and nonlocal elasticity theory to study the mechanical response of composite nanoplates

The use of composite structures, which have many layers of materials, has become more prevalent in the field of engineering. One of the advantages of this approach is its ability to use the inherent strengths of the constituent materials, resulting in a substantial increase in their load-bearing capability. Hence, this research represents the pioneering investigation into the static bending and free vibration characteristics of composite nanoplates including several layers of materials, whereby the material layers are interconnected via intricate profiles characterized by square wave and sine waveforms. The purpose of this endeavor is to fully capitalize on the benefits of attending courses in order to enhance practical working efficiency. This study also incorporates the use of two innovative third-order shear deformation theories. Simultaneously, considering the negligible size impact facilitated by the nonlocal theory, the mathematical formulations and equilibrium equations are derived using the Hamilton principle. The issue has been addressed using a four-node element with six degrees of freedom per node. One novel aspect of this study is its consideration of the impact of initial shape imperfections in various manifestations. Additionally, the elastic foundation incorporates characteristics that exhibit spatial variation. This statement provides a somewhat more accurate depiction of the behavior shown by actual structures. The numerical findings have been meticulously computed and thoroughly examined. Notably, it is possible to determine the optimal number of wavelengths in the profile to enhance the load-bearing capability of the structure. The findings derived from this study have significant value in informing the design of operational frameworks in practical settings.

DSM design of cold-formed steel fixed-ended lipped channel columns undergoing distortional-global interaction

This work reports a numerical investigation dealing with the post-buckling behaviour, strength, and Direct Strength Method (DSM) design of cold-formed steel fixed-ended lipped channel columns experiencing coupling between distortional and global (flexural-torsional) buckling − distortional-global (D–G) interaction. Various cross-section dimensions and lengths are considered, to ensure that the columns selected undergo different levels and types (“true”, “secondary-bifurcation distortional” or “secondary-bifurcation global”) of D–G interaction. The results presented and discussed, determined by means of Abaqus shell finite element geometrically and materially non-linear analyses, consist of elastic and elastic-plastic post-buckling equilibrium paths, failure loads and collapse modes. The steel material behaviour is deemed elastic-perfectly plastic and several yield stresses are considered, thus making it possible to cover a wide column D–G slenderness range. Particular attention is devoted to identifying the most detrimental initial geometrical imperfection shapes, in the sense that they lead to the lowest column failure loads. The numerical failure load data gathered are subsequently used to assess the merits of the available DSM-based design approaches developed to handle cold-formed steel columns undergoing D–G interaction. Since these design approaches are shown to be either inefficient and/or improvable, the above failure load data are also used to propose modifications/improvements aimed at achieving an efficient failure load prediction in the specific context of fixed-ended lipped channel columns. The success of this endeavour provides encouragement to the authors in their search for a safe, accurate and reliable DSM-based design approach capable of handling cold-formed steel columns with arbitrary cross-section shapes and/or end support conditions that fail in D–G interactive modes.

استخدام المجهر الألكتروني الماسح في تشخيص المعادن الطينية في بعض ترب الرز العراقية

The Middle Euphrates region, represented by the governorates of Diwaniyah and Al-Najaf, was chosen to conduct the current study. As the two governorates are famous for cultivating various varieties of rice crop. Two methods using to irrigated these soils during the growing season, and called locally wet and dry methods. The morphological features of clay minerals were studied using scanning electron microscope (SEM), to describe the changes that occurred to the mineralogical features of these minerals due to the influence of the irrigation patterns used during irrigation of these soils. The scanning electron microscope (SEM) results show that were many changes in morphological features occurs such as in size and shape of clay minerals, in particular to smectite minerals. The scanning electron microscope (SEM) figure of clays in Al-Najaf(dry) soil showed some of particles appeared as well-formed imperfect hexagonal shape, which revealed that these particles belong to the chlorite mineral. While the mica minerals were appeared in lath-shaped, and rounded flakes in clays of all studied soils. Whereas the montmorillonite particles appear as a thin, webby crust, and have a flat, perming morphology. The variation in the size of the montmorillonite particles was adopted as a basis for the occurrence of the Mg-hydroxide layer within the interlayers of montmorillonite.

A consistent approach to the definition of initial geometric imperfections for in-plane stability design of steel moment frames

Geometric imperfections can have a significant influence on the behaviour and ultimate resistance of steel structures. For the purposes of structural design, particularly design by geometrically and materially nonlinear analysis with imperfections (GMNIA), a suitable choice of imperfections, in terms of both amplitude and shape, is therefore required; an inappropriate choice of imperfections can lead to misleading results and unsafe resistance predictions. The development of a practical strategy for defining imperfection shapes in the in-plane GMNIA-based design of steel moment frames is the focus of the present study. The proposals are also suitable for GNIA-based design. Both overall sway imperfections (i.e. frame out-of-plumbness) and individual member bow imperfections, together with combinations thereof (i.e. sway-member imperfection combinations), are considered. Several methods for introducing imperfections are assessed. Each method is categorised depending upon whether the imperfection is established through: (1) direct definition or (2) the scaling of eigenmodes. The recommended direct definition-based method introduces a sway imperfection in sympathy with the applied lateral loading and member imperfections with alternating directions between storeys, as dictated by the column base boundary conditions. The recommended eigenmode-based method uses the first sway mode and determines the number of non-sway modes according to the eigenvalues under the design loading, with all non-sway modes for which the eigenvalues αcr,ns < 25 also contributing to the imperfection. The eigenmodes are scaled to ensure the bounds of the prescribed imperfection amplitudes are suitably maintained. The consistency and accuracy of the proposed methods are demonstrated for 21 different frame configurations.

Global interactive-mode imperfection generation for K6 single-layer latticed shell using generative adversarial networks

The worst imperfection shape of K6 single-layer latticed shells corresponding to the lowest nonlinear load-carrying capacity is difficult to be obtained in design owing to significant multi-modal interaction. The global interactive buckling of the K6 single-layer latticed shell is investigated numerically, and the intelligent model for generating its worst global interactive-mode imperfection is developed via generative adversarial networks (GAN). For the cases vulnerable to interactive buckling, the load-carrying capacity is found to be reduced significantly up to 35% with two-mode interaction considered, and unstable behaviour, such as the dominant mode changing due to the deformation evolution of different modal components, is observed at the post-buckling stage. Moreover, the GAN model for generating the worst imperfection shape and the artificial neural network for evaluating the corresponding ultimate load are developed based on the data obtained from numerical analysis. The time of training model to converge is less than 30 min, and the generating process using the trained model only takes a few seconds. It is demonstrated that for the K6 single-layer latticed shells, the developed models can give the worst imperfection and the corresponding ultimate load accurately and efficiently with interactive buckling considered well. This work can be used to develop the programming module for the intelligent design of latticed shells in future.

RESULTS OF ANALYTICAL RESEARCH OF THE SEED PROCESSOR OF THE IMPROVED SOWING SECTION OF THE PNEUMATIC SEEDER

According to preliminary research, the primary factor influencing the accuracy of seed placement by pneumatic seeders is the process of transferring seeds from the metering device to the point of direct entry into the furrow formed by the coulter in the soil. The first factor is related to the high velocity of the air stream, which increases the risk of seed dislodgement from the seed boot and its placement outside the furrow. This problem can be addressed by installing a seed retarder above the seed boot. The second factor lies in the imperfect shape of the seed channel in the seed boot. Seeder developers, aiming to create an "ideal" seed bed in the soil, often underestimate the importance of the shape of the seed channel. Due to the high speeds at which modern pneumatic seeders operate (1.5–4.2 m/s) and their constant vibration, seeds in the seed channel of the seed boot constantly collide with its walls, leading to changes in direction and speed of movement. This chaotic seed movement results in decreased seeding accuracy. The third factor is the complete absence or incorrect installation of a seed retarder, which should prevent seed dislodgement from the bottom of the furrow. As a result of the analytical studies, the kinematics of seed motion after ejection from the seed boot and rebound from the furrow bottom and seed retarder were considered. The obtained dependencies include the maximum height of the parabolic seed trajectory y3`, the difference in distance between the points of rebound from the ground surface and the distance traveled by the seeder Δx from the initial seed velocity Vp0, the angle of their ejection α, the height of the seed retarder placement Hu, and the angle of its inclination β. By satisfying the conditions and for the obtained dependencies in Wolfram Cloud, the following rational parameters were obtained: α = 47°, β = 0°, Hu &lt; 0.134 m. To ensure consistent seed placement at the center of the furrow bottom after rebounding from the seed retarder with a slight trajectory deviation (± 0.01 m), the profile shape of its working surface should be parabolic with the focus at point pf = 0.134 m.

Natural frequencies and modes of parametric vibrations of reservoir shell with shape imperfections

Development of software on the basis of the finite element method led to intensive creation of the numeral methods for the decision of static and dynamic problems of the thin shells. The finite element model of the thin shell has an infinite number of freedom degrees and natural frequencies, so solving the dynamics problem of the shell is difficult. If behavior of natural vibrations of the shell was researched, it is possible to talk about shell internal properties which take a great place at the forced vibrations including parametric one. It is important to take into account influence of the constant component of parametric load on natural frequencies and modes of the shell. Nowadays forming of an effective model of parametric vibrations of the shell with shape imperfections and choice of the most dangerous imperfections model remain relevant. Influence of real and modelled imperfections on natural frequencies and modes of reservoir shell parametric vibrations excited by axial load and on shell stability loss was investigated in this article. The finite element models of the shell was formed by software NASTRAN. The modelled shape imperfections as a lower buckling form of perfect shell under static pressure were presented. The real imperfections as the deviations of the shell wall from the vertical were obtained by theodolite surveying. The natural frequencies and modes of the imperfect shell taking into account the its previous stress state from action of the constant component of the parametric load were received by the Lanczos method. Investigations showed that the real imperfections of shell a little influenced on natural frequencies and modes of parametric vibrations. These decreased the critical loads on the first natural frequency on 0,58 % and increased on the second natural frequency shells on 0,79 %, but qualitatively changed the form of stability loss on these frequencies. Modelled imperfections had a greater but not considerable influence on natural frequencies and modes of the shell. But the modelled imperfections of the shell under constant component of parametric load considerably increased the critical load on the first and second natural frequency accordingly on 12,3 % and 5,26 % and changed the shell forms of stability loss. So the modelled imperfections of the shell in the form of the regular circular half-waves increased shell carrying capacity, but not decreased. This positive effect takes place at constructing of cylinder shells from the corrugated rolled sheets.

A thermo-mechanical, viscoelasto-plastic model for semi-crystalline polymers exhibiting one-way and two-way shape memory effects under phase change

A finite strain phenomenological model is developed to simulate the shape memory behavior of semi-crystalline polymers under thermo-mechanical loading. The polymer is considered to be a composite of crystalline and amorphous phases with constant volume fractions. While the amorphous phase is stable, the crystalline one is considered to change phase with temperature. Therefore, the crystalline phase is considered further to be composed of two phases, whose volume fractions are controlled by a temperature and strain dependent function: the melted phase which is soft, and the crystallized phase which is stiff.A pressure dependent viscoelasto-plastic behavior is considered for the constitutive model of the different phases. In addition to pressure dependent plasticity, additional deformation measures are applied to the crystalline phase to model temporary (imperfect shape fixity) and permanent (imperfect shape recovery) deformations in a thermo-mechanical loading cycle. Formulating a compressible plastic flow during the phase changes yields the possibility to capture both one-way and two-way shape memory effects. As a consequence, the load-dependent and anisotropic thermal expansion observed experimentally in semi-crystalline polymers during phase change is naturally captured.The model is validated within a test campaign performed on nano-composite having a semi-crystalline polymer as a base material. It is shown that the model gives close results with the tests and it is able to capture the shape fixity and shape recovery behaviors of the polymer, for both one-way and two-way shape memory effects.

Higher-order Aberrations — the Choice of Optimal Intraocular Correction in the Surgical Treatment of Cataracts. Review of the Literature

The cornea is the most powerful refractive element of the eye and plays a fundamental role in the quality of vision. Imperfection of corneas shape leads to the focusing errors formation, known as optical aberrations, which are responsible for visual performance deterioration. Understanding and assessing wavefront errors in IOL selection and calculation is great importance to achieve maximum optical outcome in the postoperative period. The article presents literature data of the effect of higher-order aberrations on the vision quality in unoperated eyes, changes of the wavefront in the eyes after cornea surgical interventions, the effect of various types of IOLs (spherical, aspherical, multifocal and EDOF) on the total error of the eye wavefront, recommendations at their choice with different severity levels of optical aberrations, as well as promising areas of research on this issue.

A probabilistic identification of the buckling resistance of imperfect cylindrical shells in axial compression

The buckling resistance of imperfect circular cylindrical shells of elastic and isotropic material subject to axial compression is studied focusing on initial geometric imperfections. Considering the imperfections as a random field, the suggested probabilistic representation of the buckling resistance parallels the deterministic dependence of buckling loads on the size and shape of imperfections. It derives from the probability density function of an imperfection size measure and the conditional probability density functions of the resistance confined to the realizations of imperfections given their size levels. The separated representation of the buckling resistance allows: (1) supplementary checking the accuracy of the random field representation, (2) classifying measured and simulated imperfections by their size and shape effects on buckling loads, (3) prospective delimiting the range of working imperfections for fabrication tolerance classes, and (4) defining the characteristic imperfection for the semi-probabilistic design. Introductory calculations illustrate the dependence of the normalized buckling loads of a shell on the shape and size of imperfections.

A hybrid path-following approach for constrained nonlinear-buckling optimization of variable stiffness composite shells with shape imperfections

Nonlinear buckling optimization of variable stiffness (VS) composite shells is computationally expensive due to frequent nonlinear analyses. Although the generalized path-following method can serve to reduce the redundant computation, it is weakened by two kinds of discontinuity. First, the design variables may not always be searched continuously in the constrained optimization. Second, the critical buckling states may not be continuous at singular points on the search path. To address this issue, a hybrid path-following approach is proposed to trace the critical buckling states in the nonlinear-buckling optimization with constraints on the realizability of the lamination parameters and the amplitude range of geometric imperfections. Firstly, the optimal search direction is determined with the sensitivity analysis of the critical buckling equations in the isogeometric continuum shell model. Then, a continuous following strategy is adopted to provide a proper initial estimate for the Newton iterations at a disconnected point. Moreover, an investigation into the singularity of the critical buckling equations is conducted to identify the discontinuous points of the critical states in a line-search. Upon detection of the singularity, a segment of path in state space is inserted to recover the continuity. Numerical experiments show that the continuity of the critical states in the optimization is well maintained, which leads to a more efficient optimization for the VS shell with shape imperfections.

A CRITICAL REVIEW ON FATIGUE ASSESSMENT APPROACH IN SHIP STRUCTURAL DETAILS

Review of the methods used in the fatigue analysis of structures has been widely used. The resulting fatigue is primarily the result of repeated loads acting on the structure both internally and externally. Internal loads are caused by the cargo loading and unloading process, while external loads are caused by sea waves. The interaction of the two loads affects the strength of the structure. In this paper, we will discuss materials, residual stresses and environmental factors that cause fatigue in structures. The focus of analysis in this critical review is on the structural details of the ship. In determining fatigue in detailed structures, it can occur in welded joints, section cuts and shape imperfections.

Residual strength of corroded ring-stiffened cylinder structures under external hydrostatic pressure

Corrosion damage to submarine pressure hulls is a crucial consideration during the structural design phase because it diminishes the structural strength of a submarine, reducing its operational depth and posing a severe risk to the life of the crew. This necessitates using a validated analytical method to estimate the residual strength and assess the safety of corrosion-affected pressure hulls. This paper presents an experimental and numerical investigation of the residual strength of corroded ring-stiffened cylinders, which are typical components of submarine pressure hulls, the main legs of semi-submersibles, and Floating Offshore Wind Turbine (FOWT) foundations. Four steel ring-stiffened cylinder models were fabricated: two remained intact, whereas the other two were artificially corroded by machining. Hydrostatic collapse tests were conducted in a pressure chamber. To evaluate the effect of initial shape imperfections caused by welding fabrication on the strength of the structure, the initial shape imperfections were measured using a three-dimensional coordinate measuring machine. The experimental results illustrate a significant reduction in the residual strengths of the two damaged models compared with those of the intact models. The collapse processes simulated using the Abaqus software package are presented, demonstrating a close agreement between the experimental results and numerical predictions.

Choice of the shape imperfections model in dynamics problems of a long flexible cylindrical shell subjected to force couples

The issue of modeling geometrical imperfections in the dynamics problems of thin-walled shells was little researched. In cases when the natural modes of shell coincided with its buckling modes, the issue of choosing a dangerous imperfection model did not arise. When these shell modes did not coincide, it was important to investigate and compare the effect of different imperfections models on the static and dynamic characteristics of such shells. The choosing the shape imperfections model of a long flexible cylindrical shell subjected to force couples, the natural and buckling modes of which did not coincide, was studied using procedures of the finite element analysis software NASTRAN. The shell wall as a set of plat rectangular elements with six degrees of freedom at the node in the cylindrical coordinate system was modeled. The action of force couples as the concentrated forces were distributed at the nodes of the shell edges in accordance to the presentation of A.S. Volmir. The linear buckling problem and the geometrical nonlinear static analysis of the perfect shell by the Lanzosh method and the Newton-Raphson one were performed, respectively. The long half-waves buckling mode was taken as the first shell imperfections model. The modeling of the second shape imperfections as the first natural mode of the perfect shell using the natural vibration analysis by the Lanzosh method was performed. The different amplitudes of geometrical imperfections in proportion to the shell thickness using a program adapted to this software were set. The results of the geometrical nonlinear static analysis of the imperfect shell by the Newton-Raphson method showed that the shape imperfection model in the form of long half-waves more reduced the values of critical buckling loads. Investigations of natural shell vibrations by the Lanzosh method revealed the same influence of different imperfections models on the natural frequencies and natural forms. We think that the shape imperfections model in the form of long half-waves in studies of forced vibrations and dynamic stability of a long flexible cylindrical shell subjected to force couples will be more effective.

Upcycling imperfect broccoli and carrots into healthy snacks using an innovative 3D food printing approach.

Vegetables are healthy foods with nutritional benefits; however, nearly one-third of the world's vegetables are lost each year, and some of the losses happen due to the imperfect shape of the vegetables. In this study, imperfect vegetables (i.e., broccoli and carrots) were upcycled into freeze-dried powders to improve their shelf-life before they were formed into food inks for 3D printing. The rheology of the food inks, color analysis of the uncooked and cooked designs, and texture analysis of the cooked designs were determined. The inks with 50% and 75% vegetables provided the best printability and shape fidelity. 3D printing at these conditions retained a volume comparable to the digital file (14.4 and 14.3 cm3 vs. 14.6 cm3, respectively). The control, a wheat flour-based formulation, showed the lowest level of stability after 3D printing. The viscosity results showed that all the food inks displayed shear-thinning behavior, with broccoli having the greatest effect on viscosity. There was a significant color difference between uncooked and cooked samples, as well as between different formulations. The hardness of the baked 3D-printed samples was affected by the type and content of vegetable powders, where carrot-based snacks were notably harder than snacks containing broccoli. Overall, the results show that 3D food printing can be potentially used to reduce the loss and waste of imperfect vegetables.

Calculation method for local–global interaction buckling capacity of stainless steel C-columns

In this paper, based on the completed experimental research, the C-section stainless steel column was simulated in ABAQUS, and the FEM results were compared with the test results to verify the accuracy of the FE model. On this basis, the FE model was used to carry out a parametric analysis of the local–global interaction (L-G) buckling capacity of the C-section stainless steel column, and the effects of the initial imperfection distribution mode, the mechanical properties of the material, and the improvement of the material strength in the corner region were investigated. When the initial geometric imperfection distribution mode is local buckling or L-G buckling, the change of imperfection shape has less effect on the occurrence of L-G buckling and the ultimate capacity of the member. Within a certain range, the stainless steel hardening coefficient and the increase strength of corner region on the L-G buckling capacity of stainless steel columns is small. The nominal yield strength of stainless steel has a more significant effect on the L-G buckling capacity. Finally, based on the parametric analysis results and the direct strength method, the calculation formula for the local–global interaction buckling capacity of stainless steel C-columns under axial compression is proposed, and the accuracy of the calculation results were verified by comparing with the test results.

Use of interpolation methods for modeling the stress-strain state of operated oil storage tanks

The aim of the research is the comparison of two approaches for computer modeling of the stress-strain state of thin-walled shells of engineering structures, considering the imperfections of the geometric shapes arising due to their operation. The object of the study is the operated steel vertical cylindrical reservoir with imperfections of the geometric shape intended for storage of petroleum products. The first, so-called classical, approach provides geometric modeling of the surface of the tank's shell with the subsequent import of the geometric model into one of the systems of finite element analysis to calculate the stress-strain state of the structure and determine its technical condition, and the possibility of further operation. The geometric modeling of the shell surface with imperfections was performed using a two-dimensional interpolation method based on the 1st order smoothness outlines implemented in the point calculus. The calculation of the stress-strain state of the shell was carried out in the SCAD Office computer complex, taking into account geometric and structural non-linearity on the basis of the octahedral tangential stress theory. The second approach assumes modeling of an array of functions of vertical deflection of the tank wall by means of interpolation, solution of an array of differential equations of the elastic cylindrical shell under axisymmetric loading, improved by introduction of vertical deflection functions of the wall, followed by two-dimensional interpolation and analysis of the deformed state of the shell based on displacements arising in the tank wall from the hydrostatic load. As a result of the effective use of two-dimensional interpolation in the process of implementing the second approach, it was possible to achieve a significant increase in the speed of the numerical solution while maintaining sufficient accuracy for engineering calculations.

Study on Global Imperfection of Modular integrated Construction Structures for Second‐order Analysis

AbstractThe global imperfection significantly influences the stability design of the Modular integrated Construction (MiC) buildings. Currently, the initial global imperfection shapes recommended for MiC structures are formulated based on steel frames whose members are continuously connected. In practice, the columns and beams in MiC structures are composed of the members of adjacent module units, which are discontinuously connected through the special joints. Ignorance of such discontinuous features in MiC structures leads to an inappropriate estimation of the structural resistance. This paper introduces a new initial imperfection shape for MiC structures considering out‐of‐verticality of module columns and eccentricity between modules, capturing the discontinuous feature. Random initial imperfection shapes were generated using Monte‐Carlo simulation based on tolerances in regulations. The proposed imperfection shape is adopted in the analysis of a typical MiC structure and the result is compared with results from existing global imperfections in design codes. This research provides a practical global imperfection for the second‐order analysis and design of steel MiC structures. Recommendation for basic value of the proposed imperfection shape is also provided.

Imperfection Sensitivity of Plastic Shear Buckling Behavior in Corrugated Web Stainless Steel beams

AbstractThe shear behavior of corrugated web beams can be highly sensitive to the presence of initial imperfections. The designer has, in general, no prior information about the mechanical and geometric imperfections of welded elements. As a solution, in a FEM‐based design, the eigen buckling deformations with an equivalent maximum magnitude are included as an equivalent initial imperfection in a nonlinear analysis to account for the simultaneous effects of geometric imperfections and residual stresses. Previous researchers investigated the effects of initial imperfections in the form of different eigenmodes found via linear buckling analysis. They concluded that the shear strength rises with mode number, with the first mode providing the most crucial condition. However, it is shown in this paper that such a methodology is not applicable to stainless steel corrugated web beams in the medium slenderness ratio range when shear yielding precedes shear buckling. It is observed that, unlike in elastic buckling, in plastic buckling the first buckling mode does not result in the minimum strength. The results show that in FEM‐based design, using the first mode instead of the critical mode as the shape of the initial imperfection can result in a maximum of 19% and 31% overestimation of the ultimate shear capacity for the imperfection amplitudes of tw and hw/200, respectively.

Assessment of the OTEC cold water pipe design under bending loading: A benchmarking and parametric study using finite element approach

Abstract Ocean thermal energy conversion (OTEC) is a floating platform that generates electricity from seawater heat. The cold water pipe (CWP) used in OTEC has a length of 1,000 m and a diameter of 10 m, making it susceptible to bending loads from ocean currents. To find suitable geometry and material for the CWP, the finite element method was used to model the real-world geometry. In the D/t variation, lower ratios (increased thickness) result in higher critical moments, maximum stress, strain, and displacement. D/t 50 was chosen for the CWP. In the L/D variation, the critical moment’s impact on L/D ratio was minimal, while reducing L/D (shorter pipe) increased strain, and larger L/D geometries had higher displacements. L/D 10 was selected as it balanced critical moments and reduced the number of stiffeners needed. For diameter size variation, larger diameters increased critical moment and strain, but smaller diameters (larger L/D ratios) also showed high strain due to necking at two points. A diameter of 12 m was chosen for its exceptionally high critical moment. Steel was selected as the suitable material due to its higher critical moment and maximum stress, despite its higher weight and lower maximum strain than composites. Capital shape imperfections had a minimal effect on the CWP’s structure as they were localized.