Strain Limit Research Articles

Numerical design calculation of bolted lap joints at elevated temperatures

This paper presents experimental and numerical studies to investigate the mechanical behaviour of bolted lap joints at elevated temperatures. The load-deformation curves, failure modes, and resistance values of the specimens were obtained from experimental studies. A solid finite element model generated using ABAQUS software was validated and verified by the experimental results and analytical models to investigate the different failure modes and predict the fire resistance of bolted lap joints at elevated temperatures, respectively. Then, the component-based finite element model (CBFEM) was prepared to analyse the fire behaviour of bolted lap joints as an alternative to design specifications for structural fire engineers. The CBFEM was verified by the validated solid model and analytical models in terms of load-deformation curve, fire resistance, and failure modes. Parametric studies were performed to investigate the influence of several parameters on the fire response of bolted lap joints. The study shows that the CBFEM may be used to design bolted lap joints at elevated temperatures and the 5 % limit strain for plates proposed in EN 1993-1-5 can be applicable for predicting the fire resistance of steel connections.

Tough and elastic hydrogel thermocells for heat energy utilization

Hydrogel thermocells possess great potential in the energy conversion field as they directly absorb waste heat from the environment to drive redox reactions for continuous electricity generation. However, achieving high toughness and good elasticity simultaneously in hydrogel thermocells remains a challenge because of the inherent contradiction of energy dissipation mechanisms, severely limiting their practical applications and lifespan. To address this, a skin-like hydrogel network with a highly dense interwoven network is developed to construct hydrogel thermocells with good elasticity and high toughness. The dense network structure can effectively disperse the stress and hinder crack propagation, thus breaking the contradiction between high toughness and good elasticity. The thermocell realizes a toughness of 460 J m−2 while reaching an elastic limit strain of 350 %, far exceeding the elasticity of previous stretchable hydrogel thermocells. Meanwhile, it exhibits ultra-low hysteresis and excellent fatigue resistance under tensile and compressive cyclic loads. Moreover, the thermocell can work stably over long periods, enabling stable voltage output even under compression, bending, and stretching. In addition, the thermocell can power the LED lamp and calculator, and can also be connected in series to form large arrays, thus rendering it an ideal power source for wearable devices.

Investigation of the influence of plane strain constrained anisotropic plastic flow on the localized necking prediction

PurposeThe purpose of this manuscript is to investigate the influence of the satisfying of plane strain conditions on the prediction of the localized necking and to evaluate this effect by the different hardening models.Design/methodology/approachHigh-order anisotropic Drucker yield function, two types of hardening models, namely Hollomon power and Voce saturated, and the modified maximum force criterion (MMFC) are employed to predict the forming limit strains of AA3104-H19 alloy. Two identification methods, namely conventional and plane strain constrained, are applied and forming limit diagrams of the material are predicted by the incorporation of the anisotropic Drucker criterion and the hardening models into the MMFC for both calibration methods.FindingsThe enhancement in the prediction accuracy of the forming limits provided by the implementation of the plane strain constrained method is strongly dependent upon the selected hardening model type in the MMFC. About 18% improvement in the prediction of the biaxial limit strains is provided via Hollomon power law hardening, whereas the opposite result is occurred in case that the Voce saturated hardening law is used, and the predictions match with the experimental data only in the plane strain point and its surroundings.Originality/valueThe plane strain constrained identification method precisely predicts the location of the plane strain point on the yield locus and also any yield stress or anisotropy coefficient in the plane strain state is not required during the calibration, therefore the method can reduce the number of the required experiments for the constitutive characterization, and it will be attractive for both academy and industry. Additionally, the improvement in the prediction of the biaxial forming limits can be provided by applying of this method along with the appropriate hardening law.

Ultrafast Polymerization of a Self-Adhesive and Strain Sensitive Hydrogel-Based Flexible Sensor for Human Motion Monitoring and Handwriting Recognition.

Hydrogel-based flexible electronic devices have great potential in human motion monitoring, electronic skins, and human-computer interaction applications; hence, the efficient preparation of highly sensitive hydrogel-based flexible sensors is important. In the present work, the ultrafast polymerization of a hydrogel (1-3 min) was achieved by constructing a tannic acid (TA)-Fe3+ dynamic redox system, which endowed the hydrogel with good adhesion performance (the adhesion strength in wood was 17.646 kPa). In addition, the uniform dispersal ensured by incorporating polydopamine-decorated polypyrrole (PPy@PDA) into the hydrogel matrix significantly improved the hydrogel's stretching ability (575.082%). The as-prepared PAM/CS/PPy@PDA/TA hydrogel-based flexible sensor had a high-fidelity low detection limit (strain = 1%), high sensitivity at small strains (GF = 5.311 at strain = 0-8%), and fast response time (0.33 s) and recovery time (0.25 s), and it was reliably applied to accurate human motion monitoring and handwriting recognition. The PAM/CS/PPy@PDA/TA hydrogel opens new horizons for wearable electronic devices, electronic skins, and human-computer interaction applications.

Stretch-forming characteristics of austenitic material stainless steel 304 at hot working temperatures

Abstract The need for sheet metal forming using highly resistant materials such as titanium alloys and stainless steel has increased recently. These materials possess elevated mean flow stress values, which make them difficult to draw at room temperature. To achieve a homogeneous distribution of strain in the stretched component, reduce the load required for plastic deformation, and greatly improve material formability, hot forming is helpful. The goal of the current study is to conduct stretch-forming experiments to investigate the forming characteristics of Austenitic material Stainless Steel (ASS) 304 at Hot working temperatures. Stretch forming experiments have been conducted on the Servo electrical sheet press test machine at 650 and 800°C. The formability has been estimated by constructing a Fracture forming diagram (FFLD), limiting the height of the dome (LDH) and the distribution of the strain of stretched cups. It has been discovered that the limit of forming bounds rises with the temperature reaching 800°C, while the DSA effect causes the necking region – the area between the safe and fracture limits ‒ to decrease with additional temperature rise from 800 to 900°C. Within the experimental limitations, it has been considered that the Hot forming of ASS 304 at 650°C gives the highest strain forming limits with a uniform strain distribution in the stretched cups. From the Formability limit diagram, dome height, and strain distribution, it can be observed that ASS 304 has good limiting strain up to 800°C with lower load application.

Formability of 2195-T4 Al–Li alloy sheet by electromagnetic forming

This study explored the efficacy of electromagnetic forming in addressing the limited formability of aluminum–Lithium (AlLi) alloy at room temperature, focusing on the AA2195-T4 sheet. Comparative analyses were conducted to assess the formability. The results indicated that the limit strains obtained through electromagnetic forming were at least 50%, 10%, and 50% higher compared with those obtained through rigid punch forming under the uniaxial tension, plane strain, and biaxial tension. Upon utilizing forming limit diagrams, the failure processes during electromagnetic flanging were predicted. Notably, electromagnetic flanging enabled the creation of hole-flanging structures with a 60% increase in the flanging limit strain around the circumference, surpassing the capabilities of rigid punch flanging. Moreover, the maximum time window for electromagnetic flanging was extended to 168 h. Analysis of the flanging strain path indicated that cracks were prone to occur near round corners during electromagnetic flanging, contrasting with rigid punch flanging where cracks tended to form near the edges of straight walls. This study offered valuable insights for aerospace component formation utilizing Al–Li alloys at room temperature.

Strain-dependent behaviour of cold recycled material mixtures in cyclic compression tests

The purpose of the study is to evaluate strain-dependent behaviour of Cold Recycled Material (CRM) mixtures using three frameworks typically applied for Hot Mix Asphalt (HMA): linear viscoelastic (LVE) limits; non-linearity directions; changes in rheological model parameters. To this aim, the complex modulus of three CRM mixtures with different bitumen-to-cement ratio (0.2, 0.6 and 1.8) was measured in cyclic compression mode, at increasing level of axial deformation (from 35 to 195 μstrain) and at three temperatures (4, 20 and 40 °C). CRM mixtures showed strong strain dependent behaviour, which does not fully comply with the LVE hypothesis. LVE limit framework is applicable, but strain limits for CRM are different from HMA. Linearity direction framework does not give unique trend, hence it is not applicable in the same way as it was developed for HMA. The most promising framework for further analysis is the change in rheological model parameters, but it requires high number of performed tests.

Enhancing Electrical Conductivity of Stretchable Liquid Metal-Silver Composites through Direct Ink Writing.

Structure-property-process relationships are a controlling factor in the performance of materials. This offers opportunities in emerging areas, such as stretchable conductors, to control process conditions during printing to enhance performance. Herein, by systematically tuning direct ink write (DIW) process parameters, the electrical conductivity of multiphase liquid metal (LM)-silver stretchable conductors is increased by a maximum of 400% to over 1.06 × 106 S·m-1. This is achieved by modulating the DIW print velocity, which enables the in situ elongation, coalescence, and percolation of these multiphase inclusions during printing. These DIW printed filaments are conductive as fabricated and are soft (modulus as low as 1.1 MPa), stretchable (strain limit >800%), and show strain invariant conductivity up to 80% strain. These capabilities are demonstrated through a set of electromagnetic induction coils that can transfer power wirelessly through air and water, even under deformation. This work provides a methodology to program properties in stretchable conductors, where the combination of material composition and process parameters leads to greatly enhanced performance. This approach can find use in applications such as soft robots, soft electronics, and printed materials for deformable, yet highly functional devices.

Evolution of Structure and Texture Formation in Thermomechanically Treated Ti-Zr-Nb Shape Memory Alloys

Biomedical Ti-22Nb-6Zr, Ti-18Zr-15Nb, and Ti-41Zr-12Nb (at.%) shape memory alloys were subjected to cold rolling (CR) and subsequent post-deformation annealing (PDA). The evolutions of phase and structure states, crystallographic texture, and crystallographic limit of recovery strain were studied using EBSD, TEM, and XRD analyses. The study found that CR (e = 1.5) and PDA at 800 °C for 30 min results in fine- and coarse-grained structures. Severe CR (e = 3.0) and PDA at 550 °C for 5 min results in a recrystallized, equiaxed, predominantly ultrafine-grained structure of the β-phase with a small amount of low-angle boundaries. Increasing the degree of CR from moderate (e = 0.3) to severe (e = 3.0) results in a favorable strong {111}β<110>β recrystallization texture. Alloys with low Zr content are more susceptible to this type of crystallographic texture formation during TMT, primarily due to a higher Nb content. The Ti-41Zr-12Nb alloy shows the highest crystallographic limit of recovery strain (εrmax ≈ 6%). The limit decreases to ≈5% (for Ti-18Zr-15Nb) and ≈3% (for Ti-22Nb-6Zr) when transitioning from high- to low-Zr alloys. The transition of Ti-Zr-Nb alloys from coarse-grained to ultrafine-grained structures of the β-phase and a decrease in grain size do not affect the crystallographic limit of recovery strain in the studied grain size ranges.

Predicting Tibia-Fibula Geometry and Density From Anatomical Landmarks Via Statistical Appearance Model: Influence of Errors on Finite Element-Calculated Bone Strain.

State-of-the-art participant-specific finite element models require advanced medical imaging to quantify bone geometry and density distribution; access to and cost of imaging is prohibitive to the use of this approach. Statistical appearance models may enable estimation of participants' geometry and density in the absence of medical imaging. The purpose of this study was to: (1) quantify errors associated with predicting tibia-fibula geometry and density distribution from skin-mounted landmarks using a statistical appearance model and (2) quantify how those errors propagate to finite element-calculated bone strain. Participant-informed models of the tibia and fibula were generated for thirty participants from height and sex and from twelve skin-mounted landmarks using a statistical appearance model. Participant-specific running loads, calculated using gait data and a musculoskeletal model, were applied to participant-informed and CT-based models to predict bone strain using the finite element method. Participant-informed meshes illustrated median geometry and density distribution errors of 4.39-5.17 mm and 0.116-0.142 g/cm3, respectively, resulting in large errors in strain distribution (median RMSE = 476-492 με), peak strain (limits of agreement =±27-34%), and strained volume (limits of agreement =±104-202%). These findings indicate that neither skin-mounted landmark nor height and sex-based predictions could adequately approximate CT-derived participant-specific geometry, density distribution, or finite element-predicted bone strain and therefore should not be used for analyses comparing between groups or individuals.

Performance Analysis of Multi-Point Incremental Forming Tool using Martensitic AISI 420 Sheet Metals

Incremental Sheet metal Forming (ISF) Process is a suitable process which helps to produce various parts used in automotive sector by rapid prototyping. This method of producing a prototype helps industry in reducing the production cost. In ISF process, a final product is evolved through local deformation of the sheet metal made by the tool. Usually better formability is obtained when the tool makes a better contact with the sheet metal throughout the process. Improved formability elevates dimensional accuracy of the product, thus increases the market value of the product. A new tool with multiple ball ends capable of making multiple mating points over sheet metal was used in this research to enhance the efficiency of formability and surface finish. Ability of the new Multi-Point Incremental Forming Tool (MPIF) was investigated and compared to the existing Single Point Forming Tool (SPIF) based on the formability and surface finish. Forming Limit Diagram (FLD), Strain Distribution (SD) and Scanning Electron Microscope (SEM) were used to examine the formability of the sheet metal. The SEM & 3D-Surface roughness profilometer were used to observe the sheet metals surface finish. In addition to these experimental techniques a simulation results were also used to predict the stress and strain rate during forming process. The experimentation and simulation outcome shows that the MPIF provides superior formability and surface finish.

Exceptional-point-enhanced phase sensing.

Optical sensors, crucial in diverse fields like gravitational wave detection, biomedical imaging, and structural health monitoring, rely on optical phase to convey valuable information. Enhancing sensitivity is important for detecting weak signals. Exceptional points (EPs), identified in non-Hermitian systems, offer great potential for advanced sensors, given their marked response to perturbations. However, strict physical requirements for operating a sensor at EPs limit broader applications. Here, we introduce an EP-enhanced sensing platform featuring plug-in external sensors separated from an EP control unit. EPs are achieved without modifying the sensor, solely through control-unit adjustments. This configuration converts and amplifies optical phase changes into quantifiable spectral features. By separating sensing and control functions, we expand the applicability of EP enhancement to various conventional sensors. As a proof-of-concept, we demonstrate a sixfold reduction in the detection limit of fiber-optic strain sensing using this configuration. This work establishes a universal platform for applying EP enhancement to diverse phase-dependent structures, promising ultrahigh-sensitivity sensing across various applications.

Static Load Testing Of PCI-Bridges for Assessing Functional Suitability and Its Comparison with Dynamic Testing

To accommodate the rapid development of residential and commercial areas in the Bumi Serpong Damai (BSD) Region, Banten, the construction of the Kadisurung bridge is necessary to integrate road networks. Before being operational to ensure the safety of bridge users, load testing is conducted. Parameters that must be met in the testing include not exceeding the strain and deflection limits during operational conditions, including when maximum loading occurs. To assess the bridge's performance during operation, research was conducted on both sides of the central span (western side bridge, JSB, and eastern side bridge, JST) with static load testing carried out with gradually increasing loads up to 50% UDL (136 tons), followed by gradual load removal. At JSB, the maximum deflection at 100% UDL, estimated from the deflection at 50% UDL, was 39.92 mm, and at JST, it was 31.67 mm, while the allowable deflection was 43.3 mm. Based on the deflection parameters, the relative capacities of JST and JSB are expressed as 108.5% and 136.7% respectively, relative to their allowable capacities. This indicates that the estimated bridge capacity using static load testing parameters is 6%-10% greater than when using parameters from dynamic load testing. Thus, the bridge is deemed suitable for operation.

In-situ failure behavior and interfacial bonding of an interpenetrating metal matrix composite reinforced with lattice-like metallic glass (Ni60Nb20Ta20) preform

Metallic glasses (MG) have an amorphous atomic structure and exhibit several exceptional properties such as high strength, hardness associated with high elastic strain limit and elastic energy storage. But MGs are also prone to brittle fracture, making them difficult to use as monolithic structural components and might better be used as a reinforcement phase in hybrid composites such as metal matrix composites (MMC). The failure behavior of composites depends on the structure of the reinforcement phase. In this work, the failure behavior of an interpenetrating MMC reinforced with a MG (Ni60Nb20Ta20) lattice-like preform and AlSi12-matrix was investigated by in-situ compression tests under scanning electron microscopy to get a better understanding of the influence of the lattice-like preform and mechanical interference between both phases. Additionally, microstructure analysis by scanning transmission electron microscopy and energy dispersive X-ray measurements were carried out to gain insight into the chemical composition of the interfaces. The failure behavior in manufacturing direction of the MMC is dominated by shear stress whereas transversely to manufacturing direction by normal stress and exhibits therefore an anisotropic failure behavior. Investigations of the interfaces show more of a mechanical than chemical bonding but in general a good interfacial bonding was confirmed.

A physically-based mixed hardening model for the prediction of the ductility limits of thin metal sheets using a CPFE approach

An advanced Crystal Plasticity Finite Element (CPFE) approach is developed to accurately predict the ductility limit strains of thin metal sheets. This method uses polycrystalline unit cells to represent the metal sheets at the macroscopic level. The macroscopic behavior of these unit cells is determined based on that of the constituent single crystals using the periodic homogenization multiscale scheme. At the single crystal scale, the constitutive framework follows a finite strain rate-independent formulation, with the flow rule governed by the Schmid law. The evolution of the single crystal yield surface is described through a physically-based mixed hardening model, where isotropic hardening is characterized by a dislocation density-based formulation, while kinematic hardening is described by the nonlinear Armstrong–Frederick model. The unit cell ductility limit strains are predicted by the Rice bifurcation criterion. The reliability of the mixed hardening model in accurately reproducing mechanical behavior is confirmed through simulations of uniaxial tension/compression loading. Then, the developed computational strategy is used to investigate the impact of key microstructural hardening parameters on the initiation of localized necking under linear strain paths. The numerical predictions reveal the significant influence of these parameters on the formability of thin metal sheets. Additionally, the analysis of ductility limits under non-linear strain paths demonstrates a strong dependency of the numerical predictions on strain path changes. The numerical predictions obtained by the developed CPFE multiscale strategy are compared with experimental results from the literature. In summary, the proposed approach provides a reliable tool for accurately predicting the ductility limits of thin metal sheets, offering valuable insights for engineering applications.

AA5052-PVC-AA5052 (Al-PVC-Al) Sandwich Sheets Forming Analysis through In-Plane Plane Stretching Tests.

Sheet metal forming is one of the key processes for the automotive sector to be considered. Sheet metal formability is being tested as received, joining them with different welding/joining processes (i.e., tailored blanks) and making them as sandwich forms to reduce the total weight of the body. These sandwich formations of sheets are an advanced method by incorporating PVC/polymer sheets in between metal sheets with a suitable binder. The present work has investigated the formability of AA5052-PVC-AA5052 (Al-PVC-Al) sandwich sheets by considering the sheet rolling direction as a parameter. The mechanical properties of base metal and sandwich sheets were evaluated by conducting the uniaxial tensile tests. For forming behaviour of Al-PVC-Al sandwich sheets, in-plane plane stretching tests were performed on the universal tensile testing machine. From the results, it has been observed that 0-degree and 90-degree rolling direction of AA5052 sheets provided almost similar forming behaviour where the 45-degree rolling direction showed less formability. The limit strains (by which the forming limit curve has been developed and the safe and failure zones are separated) are 0.043, 0.038, and 0.043 of 0°, 45°, and 90°, respectively. Considering 0°-P-90°, 90°-P-90, 0°-P-45°, 0°-P-90°, and 45°-P-45° sandwich sheets with their corresponding limit strains of 0.060, 0.058,0.057, 0.052, and 0.050, a better formability is seen in 0°-P-90° sandwich, followed by 90°-P-90, 0°-P-45°, 0°-P-90°, and 45°-P-45°. The improvement in the formability is calculated as 28.33%, 25.86%, and 24.0% in comparison with the base metal in 0-degree, 90-degree, and 45-degree rolling directions and 0°-P-90°, 90°-P-90, and 45°-P-45° sandwich sheets.

Flexible Mini‐Inductors with Ultra‐High Inductance Density Directly Cut from Soft Magnetic Amorphous Alloys by Femtosecond Laser

AbstractInductors are indispensable parts in power modules of electronic devices. With the rapid development of flexible and wearable electronic devices, developing flexible micro‐inductors with large energy storage has become an urgent task. In this research, a sophisticated femtosecond laser ablation technique is employed to craft circular spiral mini‐inductors via selective etching of soft magnetic amorphous alloy ribbons. Remarkably, while these inductors possess dimensions akin to human fingerprints, they demonstrate an impressively elevated inductance value of ≈1.15 µH at 1 MHz. The inductance density is ≈280–390 nH mm−2, which is ≈10 times larger than conventional circular spiral inductors and is attributed to the high permeability of the amorphous alloys. Furthermore, the inductors showcase commendable flexibility, marked by stellar elasticity and a bending endurance exceeding 2500 cycles, thanks to the amorphous alloys' superior elastic strain limit. When integrated with an LM2576‐3.3BT buck converter, the fabricated inductor achieved a peak power conversion efficiency nearing 70%. These findings underscore the potential of such flexible mini‐inductors in the landscape of flexible electronics.

Strain-induced modification in thermal properties of monolayer 1T-ZrS2 and ZrS2/ZrSe2 heterojunction.

This paper systematically analyzes the phonon dispersion curves of single-layer ZrS2, ZrSe2, and ZrS2/ZrSe2 heterostructures under different strains. The phonon spectra and thermal parameters of the three structures were obtained based on the density functional perturbation theory method. The upper limits of strain that different monolayers and heterojunctions can withstand were studied. The monolayers ZrSe2 and ZrS2 can withstand up to 8% biaxial tensile strain, and the ZrS2/ZrSe2 heterojunction can withstand up to 6% biaxial tensile strain. In addition, the van der Waals force of the heterojunction may cause phonon tearing in the vertical direction. The application of biaxial tensile strain can adjust the thermal properties of the system to a large extent, which is similar to the strain effect in the pristine case. When the temperature rises, the entropy enthalpy of the three structures also gradually increases, the free energy gradually decreases, and the heat capacity of the system gradually increases until it tends to be stable. Taking single-layer ZrS2 as an example, we analyzed the change curve of thermal properties of single-layer ZrS2 under tensile strain. The results show that with the gradual increase of strain, the crystal's entropy, enthalpy, and free energy change differently. In addition, the heat capacity increases slowly under high temperatures. When all systems reach the limit strain, the phonon spectrum appears to have an imaginary frequency, and the thermal properties decrease significantly. This paper uses the first-principle calculation method based on density functional theory, and the PBE exchange-correlation function based on generalized gradient approximation (GGA) is selected for a specific calculation. The density functional perturbation theory (DFPT) calculates the full kinetic matrix. Because the lattice constants of ZrS2 and ZrSe2 are similar and have similar periodicity, the corresponding unit cells are used for structural optimization and property calculation. The Brillouin zone is integrated using the K points generated by the Monkhorst-pack method. For single-layers ZrS2 and ZrSe2, 8 × 8 × 1K-point grid is selected, and for ZrS2/ZrSe2 heterojunction, 8 × 8 × 2K-point grid is selected. A vacuum layer of 30Å was added in the vertical direction to avoid interlayer interaction. The non-conservative pseudopotential method is used to optimize the structure, and the optimization convergence is set as follows: the cutoff energy is set to 700eV, the convergence threshold of the maximum force between atoms is 0.01eV/Å, the convergence threshold of the maximum energy change is set to 1 × 10-9eV, and the convergence threshold of the maximum displacement is 0.001Å.

Hydraulic-driven adaptable morphing active-cooling elastomer with bioinspired bicontinuous phases

The active-cooling elastomer concept, originating from vascular thermoregulation for soft biological tissue, is expected to develop an effective heat dissipation method for human skin, flexible electronics, and soft robots due to the desired interface mechanical compliance. However, its low thermal conduction and poor adaptation limit its cooling effects. Inspired by the bone structure, this work reports a simple yet versatile method of fabricating arbitrary-geometry liquid metal skeleton-based elastomer with bicontinuous Gyroid-shaped phases, exhibiting high thermal conductivity (up to 27.1 W/mK) and stretchability (strain limit >600%). Enlightened by the vasodilation principle for blood flow regulation, we also establish a hydraulic-driven conformal morphing strategy for better thermoregulation by modulating the hydraulic pressure of channels to adapt the complicated shape with large surface roughness (even a concave body). The liquid metal active-cooling elastomer, integrated with the flexible thermoelectric device, is demonstrated with various applications in the soft gripper, thermal-energy harvesting, and head thermoregulation.

Factors associated with COVID-19 vaccine uptake and hesitancy among healthcare workers in the Democratic Republic of the Congo.

Vaccination is a critical intervention to reduce morbidity and mortality and limit strain on health systems caused by COVID-19. The slow pace of COVID-19 vaccination uptake observed in some settings raises concerns about COVID-19 vaccine hesitancy. The Democratic Republic of the Congo experienced logistical challenges and low uptake at the start of vaccine distribution, leading to one of the lowest overall COVID-19 vaccine coverage rates in the world in 2021. This study assessed the magnitude and associated factors of COVID-19 vaccine uptake among healthcare workers (HCWs) in seven provinces in DRC. We implemented a cross-sectional Knowledge, Attitudes, and Practices (KAP) questionnaire targeting HCWs, administered by trained data collectors in Haut-Katanga, Kasaï Orientale, Kinshasa, Kongo Centrale, Lualaba, North Kivu, and South Kivu provinces. Data were summarized and statistical tests were performed to assess factors associated with vaccine uptake. HCWs across the seven provinces completed the questionnaire (N = 5,102), of whom 46.3% had received at least one dose of COVID-19 vaccine. Older age, being married, being a medical doctor, being a rural resident, and having access to or having previously worked in a COVID-19 vaccination site were all strongly associated with vaccination uptake. Vaccinated individuals most frequently cited protection of themselves, their families, and their communities as motivations for being vaccinated, whereas unvaccinated individuals were most concerned about safety, effectiveness, and risk of severe side effects. The findings suggest an opinion divide between vaccine-willing and vaccine-hesitant HCWs. A multidimensional approach may be needed to increase the acceptability of the COVID-19 vaccine for HCWs. Future vaccine campaign messaging could center around the positive impact of vaccination on protecting friends, family, and the community, and also emphasize the safety and very low risk of adverse effects. These types of messages may further be useful when planning future immunization campaigns with new vaccines.