Indirect Tension Research Articles

Conscientious Objection and the Anesthesiologist: An Ethical Dilemma.

Conscientious objection is a legally protected right of medical professionals to recuse themselves from patient care activities that conflict with their personal values. Anesthesiology is different from most specialties with respect to conscientious objection in that the focus is to facilitate safe, efficient, and successful performance of procedures by others, rather than to perform the treatment in question. This could give rise to a unique, somewhat indirect ethical tension between the application of conscientious objection and potential infringement upon patient autonomy and well-being. While some situations have clear grounds and precedent for conscientious objection (e.g., abortion, or futile procedures), newer procedures, such as gender-affirming surgery and xenotransplantation, may trigger conscientious objection for complex reasons. This review discusses ethical, legal, and practical aspects of conscientious objection; challenges to anesthesia groups, departments, and healthcare organizations when conscientious objection is invoked by anesthesiologists; and strategies to help mitigate the ethical dilemmas.

Mechanical properties and repairing mechanism of recycled cement stabilized macadam for road base based on microbial induced carbonate precipitation technology

The utilization of recycled coarse aggregate derived from construction and demolition waste (CDW) in the construction of road cement stabilized macadam base could effectively alleviate the shortage of natural sand and aggregate resources. To explore the repairing effect of microbial induced carbonate precipitation (MICP) on recycled cement stabilized macadam (RCSM), the physical, mechanical, and microscopic properties of recycled concrete aggregate under different precipitation precursor concentrations were researched in this paper. The mechanical properties of RCSM with varying contents of recycled concrete aggregate were analyzed before and after repairing. Based on scanning electron microscopy (SEM) and mercury intrusion porosimeter (MIP) tests, the microstructure and pore structure parameters of recycled concrete aggregate were explored, and the repair mechanism of MICP on RCSM was revealed via the performance analysis of recycled concrete aggregate and RCSM. The results show that MICP could effectively reduce the water absorption of recycled concrete aggregates, while simultaneously enhancing its apparent density and crushing resistance. In a certain range, the higher the concentration of the precipitation precursor, the better the repairing effect on the performances of recycled concrete aggregates. However, while the concentration of urea or calcium source concentration exceeding 1.0 mol/L, the activity of urease would start to be inhibited. The unconfined compressive strength of RCSM after MICP repairing could be increased by 22.7 % with a maximum extent compared with that before repair, while the maximum increase of indirect tension strength and flexural tensile strength was 15 % and 8.2 %, respectively. The biological CaCO3 generated by MICP reaction could fill the micro-cracks and pores of the recycled concrete aggregate efficaciously. Besides, it could also optimize the pore parameters and pore size distribution parameters, and enhance the adhesive strength of interfacial transition zone (ITZ) between cement and recycled concrete aggregates, which could improve the mechanical properties of RCSM.

Progressive Weakening of Granite by Piezoelectric Excitation of Quartz with Alternating Current

A promising solution to reduce energy usage and mitigate the wear of drilling and comminution tools during mining operations involves inducing vibrations within the piezoelectric phases dispersed in the structure of rocks using alternating current (AC). This paper presents experimental evidence of AC-induced weakening of Kuru granite, manifested as improvements in rock drillability and reductions of strength. Sievers’ J-miniature drill tests were used to assess surface drillability. The impact of AC treatment on the quasi-static strength of granite was assessed via three-point bending and indirect tension Brazilian disk tests. The influence of AC treatment on the dynamic tensile strength of the rock was determined using split Hopkinson bar tests, with the fragmentation process captured using in situ ultra-fast synchrotron X-ray phase contrast imaging. The quasi-static tests revealed no reduction in rock strength after the AC treatment. In contrast, reductions of 25% in hardness and 18% in dynamic tensile strength were observed. Fragmentation patterns differed between treated and non-treated rocks, with treated specimens exhibiting reduced macrocrack formation during loading.

Consideration of the Accuracy of Empirical and Indirect Laboratory Methods for the Characterisation of Tension Strength

This research explores the results of the most common laboratory based indirect tension strength methods over the range of UCS strengths 0.1 MPa (cemented paste backfill) to 100 MPa (concrete). The accuracy of each of the methods is considered through a comparison with direct strength measurements completed on the same material. The results of 241 individual tests suggest that the use of indirect tension methods to determine tension strength for all geo-material strength ranges may provide misleading results unless a correction-factor is applied. Correction factors that relate splitting and flexure results to direct tension results are provided. The correction factors are based on the characteristic UCS of the material. A comparison of the traditional empirical relationship to derive tension from UCS is presented and an updated relationship is proposed that is relevant over the UCS strength range 0.1–100 MPa.

Geotechnical performance of isotropic and foliated quartzite waste as aggregate for road base and asphalt mixture

Quartzite mines produce a large amount of waste. Although the reuse of materials is essential for sustainable constructions, little is known about the geotechnical properties of isotropic (massive) and foliated (discontinuous) quartzite waste. In this paper, the potential use of these wastes as base layers and asphalt mixtures were examined by a series of laboratory tests and numerical simulations. This paper presents an analysis of the particle properties, durability, strength, and deformation response of quartzite waste in isotropic (IGM) and foliated granular (FGM) mixtures. Asphalt mixtures with isotropic (IAM) and foliated (FAM) quartzite waste as aggregates are evaluated using Brazilian tensile strength, moisture susceptibility, and repeated-load indirect tension tests, such as the resilient modulus and fatigue. To estimate the performance of these materials as pavement layers, numerical experiments are also carried out using the mechanistic-empirical design framework of the MeDiNa software package. As a base material, the mixtures showed plastic creep responses at the highest stress level (higher permanent strain of 1.2 % at σ3/σd = 360/120 kPa) and negligible expansion. The California bearing ratio (higher than 130 % for both IGM and FGM) and resilient modulus (average of 224 and 130 MPa for IGM and FGM, respectively) greatly exceeded the minimum requirement of Brazilian standards. As asphalt mixtures, both IAM and FAM met the minimum limit of tensile strength, but IAM showed greater stiffness. According to the stress–strain analysis of the MeDiNa software, granular and asphalt mixtures incorporating quartzite waste fulfilled the fatigue crack area and rut depth criteria, falling within the allowed thickness ranges for road pavements subjected to up to 5×106 repetitions (medium heavy traffic). This study provides support for the transformation of quartzite waste into a valuable byproduct.

Long term behavior of rubberized concrete under static and dynamic loads

Eco-friendly recycled tire-derived rubberized concrete is an environmentally conscious alternative employed in civil engineering for diverse purposes, enhancing the characteristics of concrete. In this paper, the research focuses on examining the drying shrinkage, creep, impact, and post-impact and creep behavior of concrete incorporating rubber. Four groups of cylindrical samples, each with a diameter of 150 mm and a length of 300 mm, were subjected to a consistent load corresponding to 0.25 of the bearing load capacity determined through compression tests on identical concrete mixtures. The testing spanned a year, during which measurements were taken for total strain, dependent strain, creep, and shrinkage. The concrete mixtures were formulated with crumb rubber in place of fine aggregate sand, with varying percentages (0%, 10%, 20%, and 30%). To emphasize distinctions in outcomes across mixtures with different crumb rubber proportions, tests for compression, indirect tension, flexural strength, and impact resistance were carried out at intervals of 28 days, three months, six months, and one year. The examination and contrast of the four combinations demonstrated notable effects on both concrete creep and impact energy due to the addition of rubber particles. Despite this, shrinkage showed minimal influence. In general, there was a decrease in the compressive strength of rubberized concrete. The concrete compressive strength decreased by 25–35%, 45–50%, and 55–65% for rubberized concrete incorporating 10%, 20%, and 30% crumb rubber, respectively. Furthermore, it was observed that creep negatively affects the impact resistance of non-rubberized concrete. Nevertheless, including rubber helps mitigate the effect of creep on the impact resistance, resulting in a reduction ranging from 6% to 12% across rubber percentages from 10% to 30%.

Effects of rejuvenators and aging conditions on the properties of blended bitumen and the cracking behavior of hot asphalt mixtures with a high RAP content

The utilization of Reclaimed Asphalt Pavement (RAP) in asphalt pavement has obtained global popularity because of its cost-efficiency, technical advantages, and positive environmental influence. However, incorporating RAP requires careful consideration of cracking resistance because of the existence of age hardening of bitumen in RAP. For the mixtures containing high RAP contents, rejuvenators are often applied to enhance the performances of aged bitumen and the cracking of mixtures. This research aims to evaluate the effects of different rejuvenators on the rheological properties of bitumen and the cracking resistance of the mixture under short and long-term aging conditions. To achieve this goal, three rejuvenators - namely, RA1 (petroleum-based), RA2 (waste vegetable oil-based), and RA3 (modified soybean oil-based) were evaluated at contents of 0%, 4%, 12%, and 20%, respectively. The dynamic shear rheometer (DSR) test results show that, under unaged and rolling thin-film oven (RTFO) aging conditions, blended bitumen with RA1 and RA3 have higher G*/sinδ than RA2. Conversely, under pressure aging vessel (PAV) aging conditions, blended bitumen with RA1 and RA3 has lower G*sinδ than that with RA2. Regarding the cracking resistance, the indirect tension asphalt cracking test results show that, under short-term oven aging (STOA) conditions, the mixture using RA2 and RA3 has a higher cracking tolerance index (CTIndex) than the one with RA1. However, under long-term oven aging (LTOA) conditions, the mixture using RA1 has the highest CTIndex value. In addition, the high correlations between G*sinδ with CTIndex and post-peak slope (|m75|) and between the CTIndex and |m75| are observed.

Viscoelastic Characteristics and Mechanical Performances of Asphalt Mastic and Mixtures with Fly Ash from Municipal Solid Waste Incineration Residues

Viscoelastic Characteristics and Mechanical Performances of Asphalt Mastic and Mixtures with Fly Ash from Municipal Solid Waste Incineration Residues

Study on the characterization method of dynamic modulus for asphalt mixture under multi-factor coupling conditions

In the actual service process of asphalt pavement, the dynamic response of the pavement structure layer is induced by vehicle loads. The dynamic modulus is a crucial parameter for analyzing the mechanical response of asphalt pavement. Due to significant influences from temperature and loading frequency on test measurements, along with its time-temperature equivalence, it becomes imperative to investigate the behavior of dynamic modulus under different temperature frequencies. Furthermore, laboratory loading modes also exert substantial effects on dynamic modulus. Employing different loading modes during measurement often leads to significantly varied stress states in specimens, yielding distinct values for dynamic modulus. Therefore, this study conducts dynamic modulus tests using direct tension, uniaxial compression, and indirect tension under five test temperatures and six loading frequencies while examining its variations under different stress states and temperature frequencies. The corresponding master curves and prediction models of dynamic modulus are derived, providing a valuable reference for predicting the dynamic modulus under wide-area test conditions. Through comparative analysis of dynamic modulus values at different stress levels, the stress level is incorporated into the master curve to establish corresponding master curves of dynamic modulus. By applying relevant theories and research on time-temperature equivalence, we obtained dynamic modulus master curves for three loading modes by fitting and analyzing dynamic modulus test data at various temperatures and loading frequencies. Combining the Sigmoid model and Williams-Landel-Ferry(WLF) equation, we derived prediction models for dynamic modulus under three loading modes. Comparative analysis of dynamic modulus values under these three loading modes allowed us to establish transformation equations for the prediction models in different loading scenarios. Finally, representative dynamic modulus values for permanent deformation in typical pavement structure layers were predicted based on laboratory test results and the derived models. The research findings presented in this paper have significant implications in eliminating the influence of loading modes on dynamic modulus predictions, establishing a unified prediction model, and providing essential parameters for predicting permanent deformation and fatigue life equivalent temperature.

Laboratory cracking and interlayer bond strength performance characterization of full-scale accelerated geosynthetic reinforced asphalt concrete

This study was conducted to evaluate the performance of geosynthetic reinforced asphalt pavements through full-scale and laboratory testing. The study also investigated the field cracking performance of geosynthetic test sections under accelerated loading and validated with the laboratory cracking performance results. Three sections were constructed including: control, geogrid and geosynthetic reinforced AC. After applying the accelerated loading, cores and slabs were extracted from the wheel path (W) and outside of the wheel path (OW) to evaluate the impact of accelerated loading on cracking performance of AC. The laboratory cracking performance and shear bond strength were assessed using Indirect Tension Asphalt Cracking Test (IDEAL-CT), Interlayer Shear bond Strength (ISS), Bending beam Fatigue (BBF), and Texas overlay tests. Additionally, strain response on top of pre-existing notch was also analyzed from the accelerated test sections to monitor field cracking potential of reinforced AC and to validate it with laboratory cracking performance. According to the BFF, OT and ISS results, the W AC showed degraded performance compared to OW AC, however, IDEAL-CT test results mentioned that W AC showed better cracking performance compared to OW AC. Overall, geosynthetic reinforced AC showed better laboratory cracking performance and lower shear bond strength. At full-scale section, higher tensile strains were registered indicating that geosynthetic reinforcement can undergo potentially larger displacement without failing in the pre-existing crack area. Both laboratory and field test results compliment the findings of each other.

Laboratory performance characterization of polyolefin/ aramid fibers and synthetic aramid fibers reinforced asphalt mixtures

This study was conducted to assess the impact of combined polyolefin/aramid fibers (PFA) and pure synthetic aramid fibers (AF) reinforcement on mix design properties and laboratory performance. The study also investigated the shift in laboratory performance (rutting to cracking and vice versa) with the addition of both type of fibers. One aggregate (diabase stone), one binder type (PG58–28), and two types of aramid fibers (combined polyolefin/ aramid fibers and synthetic aramid fibers), added at 0.05% dosage by mix weight, were used to produce two fiber-reinforced asphalt mixtures (FRAM). Additionally, a control mix was also produced without any reinforcement. Mix design for control and FRAM was performed and Optimum Binder Content (OBC) was determined. The laboratory rutting and cracking performance of the mixtures was assessed using Asphalt Pavement Analyzer (APA), Flow Number (FN) and Indirect Tension Asphalt Cracking Test (IDEAL-CT). Durability and stiffness of these mixtures were also determined by performing Cantabro loss and Dynamic Modulus (DCM) tests. According to the mix design results, PFA reinforced mix showed an offset bulk and theoretical maximum specific gravity. However, both control and FRAM mixtures showed the same OBC (5.7%). Both type of fibers improved the durability of mix. With addition of PFA and AF fibers into the asphalt mix, the performance trend shifted from rut resistant mix to crack resistant mix, respectively. Furthermore, addition of PFA fibers into the asphalt mix increased the toughness and AF fibers make the asphalt mix ductile.

Effect of fiber addition on strength and toughness of rubberized concretes

In this paper, an experimental study was conducted to examine the static and dynamic behaviors of rubberized fiber-reinforced concrete (RFRC). Crumb rubber was partially replaced from sand at volume fractions of 0%, 5%, 10%, 15%, and 20%. Steel fibers (SFs) with fiber volume fractions (Vf%) of 0%, 0.5%, 1%, and 1.5% were used for the production of FRCs, while polypropylene fiber (PPF) with Vf% = 0.4% was adopted to produce others FRCs. A combination of 0.4% PPF and 1% SF was used for hybrid FRC. The static properties were evaluated through compression, indirect tension, and flexural tests. However, the drop weight impact test was conducted to assess the dynamic property by estimating the impact energy. It was observed that the replacement of sand with rubber reduced all mechanical properties of concrete. In the case of RFRC, a reduction in compressive strength, compared to samples without fibers, was noted, and this reduction increased with higher Vf%. Both toughness indices and fracture energy were affected slightly by increasing rubber percentages while markedly increased with higher Vf%. However, adding rubber and/or fibers enhanced the impact energy of concrete.

Understanding the evolution mechanism and classification criteria of tensile -shear cracks in rock failure process from acoustic emission (AE) characteristics

This study aimed to investigate the crack evolution and failure mechanism of rocks by conducting uniaxial compression tests (UCT) and Brazilian indirect tension tests (BITT) using four categories of rock specimens. Real-time acoustic emission (AE) signals were detected and recorded during rock failure processes by an AE monitoring system. The study focused on the accumulative AE hits curves, stress–strain curves, and other AE energy characteristics to divide the failure process into five stages, and determine the stress thresholds. Furthermore, the transition trend of rock crack types was analyzed based on RA-AF data. A novel classification criterion of crack types based on clustering and statistical theory was proposed, and the crack boundaries of the four rocks were determined. Additionally, the tension to shear ratios of the rocks in descending order were fine-grained granite, granite, yellow sandstone, and white sandstone. Finally, the crack development trend and failure characteristics of the rock were analyzed using the crack scale and crack dividing line. The study found that the failure mode of the rock could be predicted accurately by AE parameter analysis at Unstable Crack Growth (Stage-IV).

Study on the size effect of rock under dynamic direct tension and indirect tension

Study on the size effect of rock under dynamic direct tension and indirect tension

Evaluation of Low- and Intermediate-Temperature Cracking Performance of Fiber-Reinforced Asphalt Mixtures

This study was conducted to assess the impact of aramid fiber reinforcement on the fatigue and thermal cracking performance of asphalt mixtures at intermediate and low temperatures, respectively. The study also involved evaluating the experimental consistency and ranking fiber-reinforced asphalt mixtures (FRAMs) based on their performance. One aggregate (diabase stone), one binder type (PG 76-22), and two combinations of aramid fibers, added at different dosages, were used to produce three FRAMs. These fibers included polyolefin/aramid (PFA) fibers at 0.05% dosage by mix weight and Sasobit-coated aramid (SCA) fibers at 0.01% and 0.02% dosages. An unreinforced (control) mix was also produced without any reinforcement. All mixtures were produced at a batch plant by keeping their binder content constant (at 5.5%). The manufacturer recommended dry and wet mixing times were used for better fiber distribution and represent actual mixing conditions. The laboratory performance of plant-produced FRAMs was assessed to characterize the low- and intermediate-temperature cracking performance. The indirect tension asphalt cracking test, semi-circular bend test, three-point bending beam tests, and uniaxial fatigue tests were performed at intermediate temperature; the disk shape compact tension test and thermal stress restrained specimen test tests were performed at low temperature. Fibers were successful at improving the fatigue cracking of asphalt mixtures based on intermediate-temperature testing results. In addition, fiber reinforcement, regardless of dosage and combination, showed improvements in low-temperature (thermal) cracking performance. Furthermore, based on ranking analysis for selected performance indicators from each experiment, the SCA 0.02% reinforced mix on average showed the highest cracking resistance.

Low temperature failure behavior analysis of fiber reinforced asphalt concrete under indirect tension test using acoustic emission and digital image correlation

Failure behavior is the key property needed to be characterized in asphalt concrete at low temperature, which is one of the major influence factors for service life of asphalt pavement. In this study, the reinforcing effect of glass fiber on failure process of asphalt concrete under indirect tension (IDT) test at − 10 ℃ was investigated using acoustic emission (AE) and digital image correlation (DIC) techniques. Control asphalt concrete (CAC) with no fibers was also carried out for comparison. The evolutions of AE parameters including amplitude, count, duration, rise time and corresponding cumulative ones were obtained and analyzed to characterize the failure processes of fiber reinforced asphalt concretes (FRACs) and control one, which were compared with the results from static displacement and strain data obtained through DIC. The effect of fiber length was also investigated to better understand the reinforcing mechanism and determine the proper reinforcing fibers. The test results revealed that low temperature failure processes of CAC and FRAC could be effectively classified according to the variations of AE parameters and corresponding cumulative ones. Three and five failure stages were identified for CAC and FRACs, respectively, which could clearly reflect the reinforcing effect of glass fiber. Cumulative AE parameters presented better identification effect on fiber reinforcement than displacement or strain, while stain data exhibited favorable performance for microcrack initiation. As for the fiber length effect on damage failure process of FRAC, evolutions of cumulative AE parameters before final failure of specimen became more stable with the increase of fiber length within 6–20 mm. AE technique presented great potential for failure behavior analysis and explanation of fiber reinforcing mechanism in asphalt concrete, which also provided promising method for real-time monitoring of cracking in asphalt pavement.

Polyurethane-based composite binder for poroelastic road surface: composition, preparation and properties

To address the high cost and poor water stability of polyurethane (PU) binder used in poroelastic road surface (PERS), a type of PU-based composite binder prepared at room temperature was proposed by using PU as the main ingredient, emulsified asphalt (EA), cement, and defoamer as auxiliary agents. The stabilities of different types of polyurethane-emulsified asphalt (PU-EA) blend systems were investigated and the mix composition of the PU-EA blend system was determined through molecular dynamics (MD) simulations. The interaction mechanisms of all components of the PU-based composite binder were revealed by microscopic measurements through Fourier transform infrared (FTIR) spectroscopy and fluorescence microscopy (FM). The strength and water stability of the PERS mixture bound by the PU-based composite binder were evaluated by the indirect tension (IDT) test and the Cantabro abrasion test. The results showed that the stability of the polyether polyurethane (PEUR)-cationic emulsified asphalt (CEA) blend system was the best, and the potential energy of the PU-EA blend system was the lowest when the PU content was around 50 wt%. Both physical and chemical reactions occurred simultaneously in the polyurethane-emulsified asphalt-cement (PU-EA-C) blend system's components. The calcium silicate hydrate (C-S-H) enhanced the crosslinking gel properties of the PU-EA-C blend system. Cement improved the performance of the PERS mixture in a more efficient way than the PU. When the PU-based composite binder composed of 50 wt% PU, 41 wt% EA, 9 wt% cement, and 0.5 wt% defoamer was used, the water stability and strength performance of PERS mixture were the best. The material cost of the suggested PU-based composite binder was nearly half that of commonly used PU, while the material cost of the PERS mixture was reduced by 25%. These findings would serve as useful references for the promotion and application of PERS pavement.

Performance of fibre-reinforced landfill mined soil like fraction as an environment friendly fill material

Landfill mining is emerging as an effective strategy towards mitigation of the problems associated with legacy landfills. About 40–80% of the landfill mined waste is soil-like fraction (landfill mined soil like fraction, LMSF) that is obtained after removing the combustibles and recyclables. However, due to its lower calorific value and presence of organic content, LMSF has not found many applications except landfill cover material and filling of low-lying areas. In this context, the present study explores the strength properties of LMSF with and without fibres (coir and polypropylene fibres) through unconfined compression, direct shear, UU triaxial, cyclic UU triaxial, indirect tension and bending strength tests. Overall, the shear strength properties of LMSF are similar to sand with some cohesion. Further, the performance of LMSF with optimum fibre proportion (2% for coir fibres and 1.5% for polypropylene fibres) is quite superior under monotonic and cyclic compressive loading conditions, as well as indirect tension and flexural loading conditions. An assessment of 1 m replacement of soft soil with LMSF with/without fibre reinforcement infers substantial increase in the allowable bearing pressure of LMSF. Overall, though LMSF may need assessment/pre-treatment (as required) due to presence of organic content and any possible heavy metal concentration, utilization of LMSF would encourage the adoption of landfill mining process. The current research insights contribute in the direction of achieving sustainable infrastructure development by reduction in the landfill area that would reduce the depletion of conventionally utilized natural resources for fill applications such as sand and gravel, and contribute positively towards environment.

Key mechanisms and process features of the metal transfer and cavity evolution during underwater submerged arc welding

The key mechanisms and process features of the inner physical processes and quality improvement for the novel underwater submerged arc welding (USAW) were revealed with the employment of X-ray observation. Based on the investigation of metal transfer, cavity, and behaviors of the weld pool and flux in USAW, three kinds of droplet transfer mode were confirmed, namely the indirect transfer, direct transfer, and surface tension transfer, and the proportions of them were 81.8%,12.9% and 5.3%, respectively. Compared with underwater wet welding (UWW), the average droplet transfer period was greatly reduced from 198.5 ms to 102.8 ms, and the mean sizes were also decreased from 3.2 mm to 2.2 mm in USAW. Because far more gases were generated in USAW (4394.2 ml/min) than in UWW (755.7 ml/min), the leading gas flow dragging force acting on the droplet was much stronger in USAW, which repelled the smaller droplet to detach from the wire tip within shorter time than it did in UWW. In addition, smooth and uniform weld seam without obvious defects was produced by USAW, of which the width and reinforcement were increased and reduced by 22% and 14%, respectively. And the 4.6 mm thickness of heat-affected zone for the joint of USAW was 59% wider than that of the UWW joint, indicating the cooling rate was effectively reduced in USAW, which consequently help acquiring sound quality joints in underwater welding.

Tension Control of Twisted String Actuators in Variation of Stiffness and Original Length of Strings

Although several studies have been conducted on the modeling and control of twisted string actuators (TSAs), most have been limited to position control; the studies on tension control are limited. This study proposes an indirect tension control method for TSAs. Through comprehensive loading/unloading experiments involving frequency richness and a wide range of tension inputs, the results showed that the conventional static model is no longer valid with a fixed stiffness and constant original length of the string. Therefore, the proposed method allows the stiffness and original length variation in the static tension model, which is then considered in the control by introducing an estimation method. Second, the proposed method indirectly controls string tension by controlling the rotation angle of the motor. The inverse calculation of the desired rotation angle of the motor to achieve the desired tension is equivalent to adaptively changing feedback gains with respect to the nonlinear varying gear ratio of the TSAs. The proposed estimation method simulated the actual string tension from the low- to high-frequency and from the low- to high-tension regions within a tolerable error range. Therefore, the proposed tension controller demonstrated superior regulating and tracking performance compared with the best-tuned direct proportional–integral–derivative feedback controller in a wide range of desired tensions and bandwidths.