Terms Of Stiffness Research Articles

Influence of nonlinear motor suspension parameters on Hopf bifurcation characteristics of high-speed bogie

A dynamic model of the bogie was established to investigate the influence of the elastic suspension of the motor and some nonlinear terms on the stability of vehicle hunting motion. Linear analysis was conducted based on the root locus method and other methods, and the influence of the elastic suspension of the motor on the linear critical speed was studied. Then, based on research on linear stability, the impact of the first Lyapunov coefficient of the model on the Hopf bifurcation type was analyzed. Subsequently, the influence of the stiffness and damping cubic terms in the motor suspension on the first Lyapunov coefficient was studied, and the possibility of controlling the Hopf bifurcation type by changing the stiffness and damping cubic terms in the motor suspension was analyzed, and relevant research was conducted. The results show that the increase of the cubic term of stiffness increased the corresponding speed when the amplitude of the limit cycle was 8 mm by about 3.4 km/h, and the increase of the cubic term of damping increased the corresponding speed when the amplitude of the limit cycle was 8 mm by about 8.9 km/h. Finally, a time-domain diagram corresponding to systems with different motor suspension stiffness and damping cubic terms was presented, further explaining the role of the motor suspension cubic terms and conducting relevant validation, providing reference opinions for the design of the motor elastic suspension of multiple units.

Design and analysis of a contact-aided flexure hinge (CAFH) with variable stiffness

This paper presents a novel contact-aided flexure hinge (CAFH) with variable stiffness, which consists of a contact-aided segment, a flexible segment and a rigid part. The proposed CAFH can facilitate a compact design and provide an alternative for stiffness-variable designs under any loading conditions. With a mortise-tenon structure, the CAFH is trivially affected by friction. The design and deformation procedures of the CAFH are described in detail, followed by its theoretical kinetostatic modeling using the chained beam-constraint model. The deformation of all segments is considered in the kinetostatic model, which expands the space of design parameters for stiffness-variable designs. Then, the accuracy of the theoretical model and the variable stiffness design are verified by nonlinear finite element analysis (FEA) and experimental tests. In term of stiffness, the maximum relative errors of the theoretical model are 0.76% in Stage 1 and 0.70% in Stage 2, as compared with FEA, respectively. Further, the parameter sweep is carried out, followed by sensitivity analysis to identify the main test error sources. Finally, the multi-material scenarios are investigated preliminarily, and some outlooks are discussed.

Out-of-Plane Strengthening of Existing Timber Floors with Cross Laminated Timber Panels Made of Short Supply Chain Beech

Establishing short supply chains for timber has become important especially in Italy, which is an historically wood-importer country. Timber is an environmentally friendly construction material and a potential mean to reduce carbon footprint produced every year by the building sector. In addition to its sustainability benefits, reversible strengthening interventions can be attained for existing structures. As such, timber can be efficiently used to preserve and protect historical buildings which are, due to architectural and aesthetic values, fundamental components of the Italian cultural heritage. In this study, the use and potential of novel cross-laminated (X-Lam or CLT) timber panels made of Italian hardwood (i.e., beech) for strengthening of existing timber floors is investigated. A quantitative comparison between the mechanical performances of the proposed wood-based product and common retrofitting techniques, such as double-crossed timber planks and reinforced concrete slabs, is carried out in terms of bending stiffness (which is evaluated according to Eurocode 5), influence of weight and reversibility of intervention. It is shown that CLT panels represent a good compromise/alternative for the realisation of reversible and sustainable reinforcing interventions, with rather well promising performances.

Numerical Analysis of Residual Stresses Effect in Multi-materials

Background: In this study, the effect of mechanical and physical properties of the metal and temperature is highlighted. The purpose of this study is to analyze the effect of these stresses on multi-materials. This work aimed to conduct a three-dimensional numerical study by the finite element method on the levels and distributions of the stresses in the Al2O3/NI/HAYNES multi-materials. These stresses of thermal and mechanical origin are generally detrimental to the service life of multi-material. Methods: The use of numerical resolution by finite element method is the most suitable for complex mechanical problems. It allows a more in-depth analysis of all points of the structure. In this study, a fundamental tool was constructed to resolve the mechanical behavior of materials subjected to complex solicitations. Therefore, the ABAQUS calculation code version 6.14 was used to analyze the residual stresses. Results: By interpreting the results in terms of stress variation, we identified the areas at risk; in particular, the nature of a joint effect plays a decisive role in the assembly of the right material in its mechanical resistance. This nature is defined in terms of stiffness (Young's modulus) and differential expansion (coefficient of thermal expansion). Conclusion: The presence of strong residual stresses can constitute a risk of damage to several materials. The difference between the coefficients of thermal expansion of the two materials (metal and ceramic) linked together induces, in these two constituents, normal internal stresses. This difference determines the level and distribution of these constraints. Moreover, the sign of this difference determines the state of the normal stresses.

NEW INSIGHTS INTO THE WEB PANEL COMPONENT

AbstractThe column web panel is a fundamental component of beam‐column joints. This component has been thoroughly studied and codified in the past. In this paper, new insight on its behaviour is obtained using a large amount of high‐quality Finite Element (FE) models, covering a wide range of panel slenderness and aspect ratios. The study shows that the existing models in part 1‐8 of the current and forthcoming Eurocode 3 present a wide scatter in terms of resistance and stiffness, being unconservative in some specific cases.

COMPARATIVE STUDY BETWEEN SHELL AND SOLID FINITE ELEMENT MODELS FOR STEEL JOINTS CHARACTERIZATION

AbstractSolid and shell finite element models (FEM) are two commonly used possibilities to analyse the structural behaviour of steel joints. The choice between solid and shell models often comes down to a balance between computational resources and the level of detail required for the study. In this paper, a set of welded beam‐column joints with hot‐rolled open sections is studied using both modelling techniques. The joints' behaviour is assessed in terms of resistance and initial stiffness. An improved shell FEM is proposed. The results indicate that for the studied dataset, both techniques return comparable results. Hence, the use of shell FEM seems to be a possible alternative to solid FEM and can be efficiently used for the joint characterization.

Seismic tension testing of cast-in specialty inserts under different cyclic loading protocols

The seismic performance of an anchor is primarily evaluated through cyclic loading tests following current qualification testing guidelines such as ACI 355.2 and ETAG 001 Annex E. However, recent reports suggest that these guidelines are insufficient in assessing the ultimate performance of anchors, particularly in the post-peak region. Hence, additional qualification tests are required to supplement these guidelines. Although the testing protocol of FEMA 461 could be considered a promising alternative, there is currently no concrete research related to its application. Herein, we performed cyclic tension loading tests on recently developed headed cast-in specialty inserts using both the existing anchor qualification testing guidelines and the FEMA 461 protocol and compared their behavior in terms of strength, displacement, stiffness, and strain. The new insert anchors exhibited only negligible differences in their performance, depending on the applied loading protocols. We also discuss a more efficient cyclic loading method for evaluating the seismic performance of the anchors and subsequently propose the application of the FEMA 461 testing protocol for anchor qualification tests.

Validated, high-resolution, non-linear, explicit finite element models for simulating screw - bone interaction

Background and ObjectivePrimary stability evaluation of screw implants through pull-out or push-in experiments is commonly used to investigate the mechanism of screw loosening. Numerical models simulating these testing methods could provide an enhanced understanding of the underlying attachment mechanisms as well as save time and cost in the development of new screws. However, previous numerical models have been limited by compromises between modelling the trabecular structure at high resolution versus incorporating sophisticated mechanical properties and boundary conditions, leading to overestimated mechanical performance. The aim of this study was to overcome these limitations. MethodsWe developed explicit models incorporating the microstructure of trabecular bone, with frictional contact, and a non-linear material model incorporating damage. One model digitally inserted the screw into the trabecular bone structure using Boolean operations, while another model simulated the screw's rotational insertion. ResultsThe results showed a strong correlation between numerical and experimental results (R2: 0.54–0.93) for force-displacement response in terms of stiffness and strength. We found that the damage induced by the screw insertion process is an important factor to be considered, as the absence of modelling it led to an overestimated stiffness in previous studies. ConclusionsThe study highlights the importance of including frictional contact and also identified screw insertion damage as an important part of the simulating screw-bone interaction. Our findings demonstrate the potential of explicit finite element models for accurately replicating experimental push-in results and optimizing orthopaedic screws. The code is available at https://github.com/zhou436/Bone-Screw-Constructs-eFEM.

Dynamic characteristics investigation of a dual rotor-casing system considering the comprehensive stiffness of the intermediate bearing

This paper focuses on the vibrational properties of a dual rotor-casing coupled system with nonlinear clearance in the intermediate bearing, considering both the oil film stiffness and Hertzian contact stiffness between rolling elements and raceways. A comprehensive stiffness model for the intermediate bearing has been developed based on elastohydrodynamic lubrication (EHL) and Hertz contact theory. Subsequently, a dynamical model of the dual rotor-bearing-casing system is established using the finite element method, thereby verifying the feasibility of simulating the casing with beam elements. The dimensionality of the system equation is reduced using the fixed-interface component mode synthesis (CMS) method, and the resulting reduced-dimensionality equation is solved using the improved Newmark-β method. The effects of casing support, rotational speed, and radial clearance on the vibration characteristics of the system are investigated. Then, the comprehensive stiffness and coupled vibration characteristics of the system are analyzed to elucidate its intrinsic mechanism. Finally, the contact characteristics within the intermediate bearing under dynamic load are also studied. The results indicate that the support stiffness of the casing has a more significant impact on the second resonance caused by both the inner and outer rotors. The system is prone to experiencing varying compliance (VC) resonance at low rotational speeds. The excessive bearing clearance leads to complex vibrational characteristics of the system, making it challenging to predict its motion. The impact of minor changes in stiffness on system vibration is small when the comprehensive stiffness is large. At this time, the limited effect of oil film stiffness allows it to be disregarded in terms of comprehensive stiffness. Furthermore, the speed significantly influences the contact characteristics within the intermediate bearing under the unbalanced force of the rotor and gravity.

Seismic Response of RCC Buildings on Hill Slopes with Step Back and Step Back - Set Back Configuration

Framed structures constructed on hill slopes have different structural behavior than those on flat ground due to the scarcity of flat land. As these buildings are unsymmetrical, they attract large amounts of shear forces and torsional moments, leading to unequal distribution due to varying column lengths. In this study, the dynamic response of hill buildings has been compared with step back and step back set back building without and with bracing at corner of the building in terms of maximum storey stiffness and storey displacement. Two different types of buildings have been modeled and analyzed using ETABS v 18.0 finite element code. A parametric study has been conducted, in which hill buildings are geometrically varied in height of the structure due to hill slope. All sixteen analytical models have been subjected to seismic forces along and across the hill slope direction and analyzed by using the Response Spectrum Method.
 All 16 models were analysed using ETABS v18. Three dimensional space frame analysis is carried out for four different configurations such as step back buildings with bracings at corner of the building, step back buildings without bracings, step back and set back building with bracings at corner of the building, step back and set back building without bracings. The maximum storey stiffness and storey displacement for the step back and step back-setback buildings with and without bracing are at 15 ͦ and 30 ͦ, respectively, compare with bracing buildings, the value in step back & step back set back building drastically decreases, resulting in the stability of the building.

A novel and sustainable rubber composite prepared from electric arc furnace slag as carbon black replacement

Carbon black (CB) is the most widely used reinforcing filler for rubber. Nowadays there are several concerns regarding this traditional petroleum-based filler: on one side its environmental footprint is enormous and its production process is no more sustainable and on the other side its price increases annually. For these reasons, sustainable alternative fillers are being studied. In the present research the main waste of the steel industry, namely the steel slag from electric arc furnace (EAF), is investigated as non-conventional filler for a nitrile butadiene rubber matrix (NBR). The slag has been characterized to ensure its safe reuse as filler according to the heavy metals leaching. The slag filled compounds have been characterized and compared to CB filled compounds, in terms of processability by rheometric parameters, mechanical properties, Payne effect, and physicochemical properties to investigate the filler-matrix interaction. From the obtained results, it was shown that EAF slag-filled NBRs are comparable to CB filled NBRs in terms of crosslink kinetics and, when compared at the same hardness level, are comparable in terms of viscosity, stiffness, and elongation at break, while when compared at the same filler volume fraction are similar in terms of compression set and stress relaxation.

Design of a torsional stiffener for a cable-driven hyper-redundant robot composed of gear transmission joints

AbstractThis work describes the advancement in developing a cable-driven gear transmission joint designed as a basic element for a long-reach hyper-redundant robot. Hyper-redundancy allows the robot to perform auxiliary tasks such as obstacle avoidance and joint limits satisfaction. This feature makes hyper-redundant robots particularly useful for performing tasks in confined and hazardous environments and areas that are not reachable by a human operator. The long-reach feature of the robot requires a detailed study of the overall structure and its components. The joint must be capable of transmitting forces and movements over a long distance without losing the precision and accuracy of the end-effector, so it is designed to optimise the robot’s performance in terms of stiffness, structural resistance, and functional characteristics. In light of the above considerations, the main focus of this work is to improve the structural performance of the entire robotic system. Consequently, since the most critical component of the robot in terms of torsional deformation is the gear transmission joint, this paper aims to design a torsional stiffener element to reduce its deformation and, thus, an increase of torsional stiffness of the overall robotic system. Tube-shaped and rectangular-shaped stiffener elements, which can fit the joint design satisfying its geometrical constraints, are proposed. A computer-aided engineering approach is implemented to improve the precision of positioning of the end-effector by adding stiffener elements in the joint. Two sensitivity analyses, varying the geometry of the proposed stiffener elements, are performed to evaluate their performance in terms of added mass and displacement reduction.

Biomechanical Comparison Between Double-Row Repair and Soft Tissue Tenodesis for Treatment of Proximal Rectus Femoris Avulsions.

Some patients with proximal rectus femoris (PRF) avulsions require surgical treatment after failed nonoperative treatment. There is no consensus on the superiority of suture anchor repair with the suture-bridge repair (SBR) technique versus tenodesis repair (TR) for PRF avulsions. To compare the failure load and elongation at failure between SBR and TR and to compare the stiffness of these 2 repair techniques versus the native state. Controlled laboratory study. Seven pairs of human cadaveric hemipelvises were dissected to the PRF and sartorius origins. Each specimen underwent preconditioning followed by a distraction test to determine the stiffness of the native specimen. One specimen of each pair received one of the repair methods (SBR or TR), while the other specimen in the pair received the other repair technique. After repair, each specimen underwent preconditioning followed by a pull to failure. The failure load, elongation at failure, stiffness, mode of failure, and stiffness as a percentage of the native state were determined for each repair. The SBR group exhibited a stronger failure load (223 ± 51 N vs 153 ± 32 N for the TR group; P = .0116) and significantly higher stiffness as a percentage from the native state (70.4% ± 19% vs 33.8% ± 15.5% for the TR group; P = .0085). While the stiffness of the repair state in the SBR group (41.5 ± 9.4 N/mm) was not significantly different from that of the native state (66.2 ± 36 N/mm), the stiffness of the repair state in the TR group (20.3 ± 7.5 N/mm) was significantly lower compared with that of the native state (65.4 ± 22.1 N/mm; P < .001) and repair state in the SBR group (41.5 ± 9.4 N/mm; P = .02). The SBR group primarily failed at the repair site (71%), and the TR group primarily failed at the suture-sartorius interface (43%) and at the muscle (29%). SBR and TR specimens were significantly weaker than the native tendon. The stiffness of the SBR was equivalent to that of the native tendon, while TR was significantly less stiff than the native tendon. The SBR was superior to TR in terms of failure load, stiffness, and percentage stiffness from the native state. SBR may be a better surgical option than TR to optimize failure load and stiffness for PRF avulsions.

Isotropic cellular structure design strategies based on triply periodic minimal surfaces

Isotropy is a desired characteristic in cellular structures for load bearing and energy absorption applications that must respond uniformly under external loads in all orientations. Triply periodic minimal surface (TPMS) cellular structures are attracting much attention for such applications due to their demonstrated high performance, tailorable properties, and open cell architecture. However, TPMS structures usually display stiffness anisotropy. In this work, new design strategies are presented for isotropic TPMS-based cellular structures, revealing a large available design space in terms of relative density and relative stiffness. The first design strategy arranges TPMS-based cells in a Simple-Cubic/Face-Centred Cubic inspired pattern, resulting in reduced elastic anisotropy. Two parametric optimisation approaches involving level-set mid-surface offsetting and the functional grading of relative density are then applied in a second step to eliminate any residual elastic anisotropy. Anisotropy is characterised through finite element analysis using the Zener ratio. Four families of cells are optimised, each based on a different TPMS unit cell, and then additively manufactured using the material extrusion process with polylactic acid. Finally, experimental quasi-static compressive tests are conducted to characterise stiffness, strength, and energy absorption properties. Optimised designs are tested in three crystal orientations ([001], [101] and [111]) and manufactured in three orthogonal print orientations. The Primitive TPMS-based design is the stiffest of the four designs reaching 64.4% of the Hashin-Shtrikman upper bound of bulk modulus at 20% relative density. Experimental results validate all four optimised cell designs for elastic isotropy and indicate that all the cell designs are also isotropic in terms of crushing strength and energy absorption.

Multifunctional Wound Curation Dressing Material FemuFrost─An Antioxidant-Loaded Nanoemulsion Frosted Patch of Poly(vinyl alcohol) and Hyaluronic Acid.

The wound curation dressing material should own explicit elements to aggrandize wound cessation. The cryogel of poly(vinyl alcohol) (PVA) and hyaluronic acid (HA) is deemed to promote the angiogenesis, production of extracellular matrix components, granulation, and epithelialization. The research aims to tailor and evaluate the composite PVA/HA cryogel ingrained ferulic acid-loaded nanoemulsion patch labeled as PH-FemuFrost to improve the therapeutic properties and mechanical strength of the patches. The PH-FemuFrost exhibited a water uptake capacity of 268 ± 15.07%, porosity of 70.52 ± 7.4%, and 48.62 ± 2.2% in vitro degradation. The texture analysis revealed the improved mechanical properties of PH-FemuFrost in terms of burst strength and stiffness. The PH-FemuFrost exhibited in vitro antioxidant and antimicrobial activity against Staphylococcus aureus and Candida albicans species. The wound healing efficiency of PH-FemuFrost patches was significantly increased than blank PVA-HA patches. The groups treated with PH-FemuFrost exhibited a dense network of collagen type 1 in comparison to negative and PVA-HA groups. The normal skin and healed skin exhibited parallel arrangement of type I collagen fibers toward the skin. The levels of inflammatory mediators such as IL-6 (p value < 0.0001), IL-22 (p value 0.0098), and TNF-α levels (p value < 0.0001) of PH-FemuFrost is significantly reduced compared to the negative group.

Facile-Solution-Processed Silicon Nanofibers Formed on Recycled Cotton Nonwovens as Multifunctional Porous Sustainable Materials.

Limited efficiency, lower durability, moisture absorbance, and pest/fungal/bacterial interaction/growth are the major issues relating to porous nonwovens used for acoustic and thermal insulation in buildings. This research investigated porous nonwoven textiles composed of recycled cotton waste (CW) fibers, with a specific emphasis on the above-mentioned problems using the treatment of silicon coating and formation of nanofibers via facile-solution processing. The findings revealed that the use of an economic and eco-friendly superhydrophobic (contact angle higher than 150°) modification of porous nonwovens with silicon nanofibers significantly enhanced their intrinsic characteristics. Notable improvements in their compactness/density and a substantial change in micro porosity were observed after a nanofiber network was formed on the nonwoven material. This optimized sample exhibited a superior performance in terms of stiffness, surpassing the untreated samples by 25-60%. Additionally, an significant enhancement in tear strength was observed, surpassing the untreated samples with an impressive margin of 70-90%. Moreover, the nanofibrous network of silicon fibers on cotton waste (CW) showed significant augmentation in heat resistance ranging from 7% to 24% and remarkable sound absorption capabilities. In terms of sound absorption, the samples exhibited a performance comparable to the commercial standard material and outperformed the untreated samples by 20% to 35%. Enhancing the micro-roughness of fabric via silicon nanofibers induced an efficient resistance to water absorption and led to the development of inherent self-cleaning characteristics. The antibacterial capabilities observed in the optimized sample were due to its superhydrophobic nature. These characteristics suggest that the proposed nano fiber-treated nonwoven fabric is ideal for multifunctional applications, having features like enhanced moisture resistance, pest resistance, thermal insulation, and sound absorption which are essential for wall covers in housing.

Impact of Zn alloying on structural, mechanical anisotropy, acoustic speeds, electronic, optical, and photocatalytic response of KMgF3 perovskite material

This study explores the optoelectronic potential of advanced perovskite materials, with a primary focus on alloying KMgF3 with 3d transition metals. Through this alloying process, the study employs density functional theory (DFT) with the GGA-PBE functional to tailor the atomic structure and various properties, including optoelectronic, mechanical, acoustic, anisotropic, and photocatalytic attributes. The introduction of Zn to KMgF3 triggers a noticeable bandgap redshift and significant improvements in mechanical stability and photocatalytic performance. Increasing Zn content induces a transition in KMgF3's crystal structure to a pseudo-cubic tetragonal form, which remains mechanically stable for both pristine KMgF3 and KMg(1-x)ZnxF3. Zn inclusion introduces versatile nonlinearity in terms of brittleness, stiffness, mechanical strength, and thermal behavior. This comprehensive analysis underscores anisotropy, mixed bonding, Debye fluctuations, and melting temperature variations. Notably, among the systems examined, KMg0.25Zn0.75F3 stands out as an outstanding candidate for applications in photovoltaics and water splitting, thanks to its exceptional optical performance.

The nonlinear mechanics of highly extensible plant epidermal cell walls.

Plant epidermal cell walls maintain the mechanical integrity of plants and restrict organ growth. Mechanical analyses can give insights into wall structure and are inputs for mechanobiology models of plant growth. To better understand the intrinsic mechanics of epidermal cell walls and how they may accommodate large deformations during growth, we analyzed a geometrically simple material, onion epidermal strips consisting of only the outer (periclinal) cell wall, ~7 μm thick. With uniaxial stretching by >40%, the wall showed complex three-phase stress-strain responses while cyclic stretching revealed reversible and irreversible deformations and elastic hysteresis. Stretching at varying strain rates and temperatures indicated the wall behaved more like a network of flexible cellulose fibers capable of sliding than a viscoelastic composite with pectin viscosity. We developed an analytic framework to quantify nonlinear wall mechanics in terms of stiffness, deformation, and energy dissipation, finding that the wall stretches by combined elastic and plastic deformation without compromising its stiffness. We also analyzed mechanical changes in slightly dehydrated walls. Their extension became stiffer and more irreversible, highlighting the influence of water on cellulose stiffness and sliding. This study offers insights into the structure and deformation modes of primary cell walls and presents a framework that is also applicable to tissues and whole organs.

Evaluation of gelatin-based hydrogels for colon and pancreas studies using 3D in vitro cell culture.

Biomimetic 3D models emerged some decades ago to address 2D cell culture limitations in the field of replicating biological phenomena, structures or functions found in nature. The fabrication of hydrogels for cancer disease research enables the study of cell processes including growth, proliferation and migration and their 3D design is based on the encapsulation of tumoral cells within a tunable matrix. In this work, a platform of gelatin methacrylamide (GelMA)-based photocrosslinked scaffolds with embedded colorectal (HCT-116) or pancreatic (MIA PaCa-2) cancer cells is presented. Prior to cell culture, the mechanical characterization of hydrogels was assessed in terms of stiffness and swelling behavior. Modifications of the UV curing time enabled a fine tuning of the mechanical properties, which at the same time, showed susceptibility to the chemical composition and crosslinking mechanism. All scaffolds displayed excellent cytocompatibility with both tumoral cells while eliciting various cell responses depending on the microenvironment features. Individual and collective cell migration were observed for HCT-116 and MIA PaCa-2 cell lines, highlighting the ability of the colorectal cancer cells to cluster into aggregates of different sizes governed by the surrounding matrix. Additionally, metabolic activity results pointed out to the development of a more proliferative phenotype within stiffer networks. These findings confirm the suitability of the presented platform of GelMA-based hydrogels to conduct 3D cell culture experiments and explore biological processes associated with colorectal and pancreatic cancer.

Impact of doping on the mechanical properties of conjugated polymers.

Conjugated polymers exhibit a unique portfolio of electrical and electrochemical behavior, which - paired with the mechanical properties that are typical for macromolecules - make them intriguing candidates for a wide range of application areas from wearable electronics to bioelectronics. However, the degree of oxidation or reduction of the polymer can strongly impact the mechanical response and thus must be considered when designing flexible or stretchable devices. This tutorial review first explores how the chain architecture, processing as well as the resulting nano- and microstructure impact the rheological and mechanical properties. In addition, different methods for the mechanical characterization of thin films and bulk materials such as fibers are summarized. Then, the review discusses how chemical and electrochemical doping alter the mechanical properties in terms of stiffness and ductility. Finally, the mechanical response of (doped) conjugated polymers is discussed in the context of (1) organic photovoltaics, representing thin-film devices with a relatively low charge-carrier density, (2) organic thermoelectrics, where chemical doping is used to realize thin films or bulk materials with a high doping level, and (3) organic electrochemical transistors, where electrochemical doping allows high charge-carrier densities to be reached, albeit accompanied by significant swelling. In the future, chemical and electrochemical doping may not only allow modulation and optimization of the electrical and electrochemical behavior of conjugated polymers, but also facilitate the design of materials with a tunable mechanical response.