Plane Stiffness Research Articles

Comparison of Bending Stiffness between String of Pearls Plate-Bone Substitute Constructs with and without Bending Tees in a Fracture Gap Model

Abstract Objective The aim of this study was to compare the bending properties of String of Pearls plate-bone substitute constructs with and without bending tees in the nodes over a simulated fracture gap. It is hypothesized that the constructs with tees will have higher bending stiffness. Study Design Acetal polymer tubes and 12-hole, 3.5-mm String of Pearls plates were used to create plate-bone substitute constructs simulating stabilization in a bridging fashion over a 45-mm gap. Twenty-four constructs were made with 12 containing tees in the nodes over the fracture gap. Single-cycle load-to-failure 4-point bending was performed in mediolateral and craniocaudal planes. Bending stiffness was compared with a t-test (p < 0.05). Results All plate-bone substitute constructs had a permanent loss of structural integrity via plastic deformation of the plate. The bending stiffness (mean ± standard deviation) of the craniocaudal group was 59.11 ± 1.98 N/mm with tees and 59.25 ± 1.69 N/mm without tees (p = 0.88). In the mediolateral group, the bending stiffness was 43.17 ± 0.75 N/mm with tees and 41.09 ± 0.91 N/mm without tees (p = 0.0042). Conclusion In 4-point bending, the plate-bone substitute constructs with tees had equivalent bending stiffness in the craniocaudal plane and increased bending stiffness in the mediolateral plane. However, with a small absolute difference in values, the clinical significance is unclear. Future studies for cyclic bending, torsional, and axial compression tests should be performed to further investigate the value of tees in the nodes over a comminuted or gap fracture repaired in a bridging fashion.

Experimental study on the blast resistance of polyurea-coated aramid fabrics

This paper investigates overpressure attenuation capacity and failure mechanism of the polyurea-coated aramid fabric (PCAF) subjected to air-blast loading experimentally. The peak overpressure, arrival time and positive pressure duration of shock waves on the blast and back side of PCAFs were obtained in tests and analyzed. In addition, the failure mode and mechanism were revealed with the electron scanning microscope (SEM), meanwhile the effect of polyurea type, coating position and thickness ratio on the blast resistance were discussed. The results show that in the cases of scaled distances of 1.84 and 2.32 m/kg1/3, PCAFs, one-layer polyurea coated on three-layer aramid woven fabrics, can attenuate the peak overpressure by about 70 %, delay the arrival time by about 0.7 ms, and shorten the positive pressure duration by 10 %-50 %. This is due to the increased out-of plane stiffness and closure of interweaving apertures of the aramid fabric. Furthermore, perforation is the main failure mode of aramid fabrics, in which the tensile breakage in weft yarn and the frictional slip in warp yarn, while the failure modes of PCAF mainly include fracture and exfoliation, with both weft and warp yarns breakage and polyurea failure. It was concluded that the degree of infiltration between the polyurea and fabric affects mechanical properties of the fiber, changing the failure mode of PCAF. In terms of the extent of damage, the PCAF exhibits a superior blast resistance when the polyurea coated on the back side. The blast resistance of PCAF increases first then decreases with an increase in the thickness of the polyurea layer under the same areal density.

Design, Analysis, and Validation of a Passive Parallel Continuum Ankle Exoskeleton for Support and Walking Assistance

Abstract In this paper, we propose a novel passive parallel continuum ankle exoskeleton that can provide assistive torque during ankle plantar flexion. Due to the flexible branches arranged in compliance with ankle motion and shape, the compact design can also offer some vertical support. The proposed parallel mechanism consists of two types of branches. The first type is a pre-bent flexible rod, mainly used to apply assistive force/torque during ankle plantar flexion. The second type of branch consists of a bounded sphere joint, flexible rod, and bounded sphere joint (BFB), which is mainly used for support. We formulate the kinetostatic model of the BFB branch as a series of parallelizable unconstrained optimization problems to ensure efficient solvability. After that, we derive the kinetostatic model of the proposed mechanism. After calibration, the wrench error of the kinetostatic model is 9.07%. Simulation analysis based on the calibrated model shows that the designed mechanism has high supporting stiffness and low rotational stiffness. The assistive torque caused by the nonlinear rotational stiffness in the sagittal plane is similar to that of passive clutch-like mechanisms. These properties can still be maintained when the joint center changes within a small range. Besides, a walking experiment was conducted, and the results show that the proposed design can reduce gastrocnemius activity.

Evaluation of the Stability of Internal Fixation Constructs in a Low Distal Tibia Extra-articular Cadaveric Fracture Model: A Comparative Biomechanical Study.

Introduction Despite the recent advances in implant design, the choice of an internal fixation modality for extra-articular distal tibia fractures remains controversial, and there is sparse literature comparing the stability of intramedullary nails and locked plates for such fractures. Hence, we conducted a biomechanical study on an AO type 43A3 tibia fracturecadaveric model stabilized by four different constructs, viz., intramedullary (IM) interlocking nail, anteromedial plate, anterolateral plate, and posterior plate.An AO type 43A3 fracture is defined as an extra-articular fracture of the distal tibia with metaphyseal comminution. Methods A biomechanical comparative study on formalin-preserved human cadaveric tibiae was undertaken; a total of four groups were tested, with eight bones in each group. Out of the 32 cadaveric tibiae, 19 bones belonged to male cadavers, and 13 bones belonged to female cadavers. All bones were dissected from age-appropriate cadavers and fixed with an implant, followed by the creation of a 1 cm osteotomy to simulate an AO type 43A3 fracture. All fixation constructs were subjected to three-point bending tests in the anteroposterior (AP) and mediolateral (ML) planes. Three parameters, viz., bending stiffness, peak fracture gap angle, and neutral zone, were evaluated on the load-displacement curves. Afixation construct was deemed biomechanically stable if it had a highbending stiffness, a low neutral zone (inherent toggle in the construct by its weight), and a low peak fracture gap angle. Results Out of the four implants tested, locked IM nails exhibited the maximum biomechanical stability in terms of higher bending stiffness, smaller peak fracture gap angle, and smaller neutral zones. The IM nail exhibited the highest bending stiffness in the AP plane, and the anterolateral plate had the lowest bending stiffness, and the difference was statistically significant (p= 0.032).In the AP plane, the anterolateral plate exhibited a bending stiffness of 1.51 ± 0.69 Nm/degree, whereas the intramedullary nail exhibited a bending stiffness of 2.34 ± 0.81 Nm/degree, and the posterior locked plate had a bending stiffness of 1.57 ± 0.44 Nm/degree. In the ML plane, the anterolateral plate exhibited the highest neutral zone as compared to the intramedullary nail, which had the lowest neutral zone, and the difference was statistically significant (p = 0.019). The intramedullary nail exhibited the lowest neutral zone of 0.46 ± 0.31 degrees, whereas the posterior locked plate exhibited a neutral zone of 0.78 ± 0.43 degrees in the ML plane. The anterolateral plate exhibited a neutral zone of 1.43 ± 1.00 (expressed as mean ± SD) degrees in the mediolateral plane. Conclusion Our biomechanical study supports the recommendations of using a locked intramedullary nail for AO type 43A3 fractures. We concluded that the anterolateral plate construct exhibited the least biomechanical stability, in terms of lower AP bending stiffness and higher neutral zone. If the surgeon must choose a locked plating technique for any reason, the anterolateral locking plate should be avoided. If plating is at all required, we can recommend both anteromedial and posterior locked plating as biomechanically sound options.

Single-layer PtSe2 adsorbed with non-metallic atoms: geometrical, mechanical, electronic and optical properties and strain effects.

Recently, single-layer PtSe2, possessing high carrier mobility and optical response, has been successfully fabricated. To further expand its application scope and find new physics, in this work, we functionalized it via the adsorption of non-metallic atoms X (X = H, B, C, N, O, and F) to form hybrid systems X-PtSe2, and their geometrical, mechanical, electronic, and optical properties as well as strain tuning effects were studied deeply. Calculations show that the energy stability of X-PtSe2 systems is significantly enhanced, and they also hold higher thermal and mechanical stability. Particularly, X-PtSe2 systems present excellent in-plane tenacity and out-of plane stiffness against deformations, which make them more applicable for designing nanodevices. Intrinsic PtSe2 is a semiconductor, while the X-PtSe2 system can be a band-gap narrowed semiconductor or metal, thus expanding the application scope for PtSe2, and the odd-even effect of electronic phase variation related to the atomic number is found. Besides, the wavelength range of optical adsorption is increased in X-PtSe2 systems, implying that its optical response region is wide, providing more options for developing optoelectronic devices. Moreover, it is shown that strain can flexibly tune the electronic property of X-PtSe2 systems, especially enhancing the optical absorption ability substantially, beneficial for their applications in solar devices.

Biomechanical comparison of open Bankart repair vs. conjoint tendon transfer in a 10% anterior glenoid bone loss shoulder instability model

The treatment of shoulder instability in patients with subcritical glenoid bone loss poses a difficult problem for surgeons as new evidence supports a higher failure rate when a standard arthroscopic Bankart repair is used. The purpose of this study was to compare a conjoint tendon transfer (soft-tissue Bristow) to an open Bankart repair in a cadaveric instability model of 10% glenoid bone loss. Eight cadaveric shoulders were tested using a custom testing system that allows for a 6-degree-of-freedom positioning of the glenohumeral joint. The rotator cuff muscles were loaded to simulate physiologic muscle conditions. Four conditions were tested: (1) intact, (2) Bankart lesion with 10% bone loss, (3) conjoint tendon transfer, and (4) open Bankart repair. Range of motion, glenohumeral kinematics, and anterior-inferior translation at 60° of external rotation with 20 N, 30 N, and 40 N were measured in the scapular and coronal planes. Glenohumeral joint translational stiffness was calculated as the linear fit of the translational force-displacement curve. Force to anterior-inferior dislocation was also measured in the coronal plane. Repeated measures analysis of variance with a Bonferroni correction was used for statistical analysis. A Bankart lesion with 10% bone loss increased the range of motion in both the scapular (P=.001) and coronal planes (P=.001). The conjoint tendon transfer had a minimal effect on the range of motion (vs. intact P=.019, .002), but the Bankart repair decreased the range of motion to intact (P=.9, .4). There was a significant decrease in glenohumeral joint translational stiffness for the Bankart lesion compared with intact in the coronal plane (P=.021). The conjoint tendon transfer significantly increased stiffness in the scapular plane (P=.034), and the Bankart repair increased stiffness in the coronal plane (P=.037) compared with the Bankart lesion. The conjoint tendon transfer shifted the humeral head posteriorly at 60° and 90° of external rotation in the scapular plane. The Bankart repair shifted the head posteriorly in maximum external rotation in the coronal plane. There was no significant difference in force to dislocation between the Bankart repair (75.8±6.6 N) and the conjoint tendon transfer (66.5±4.4 N) (P=.151). In the setting of subcritical bone loss, both the open Bankart repair and conjoint tendon transfer are biomechanically viable options for the treatment of anterior shoulder instability; further studies are needed to extrapolate these data to the clinical setting.

The Influence of Fiber Orientation of the Conus Elasticus in Vocal Fold Modeling.

While the conus elasticus is generally considered a part of continuation of the vocal ligament, histological studies have revealed different fiber orientations that fibers are primarily aligned in the superior-inferior direction in the conus elasticus and in the anterior-posterior direction in the vocal ligament. In this work, two continuum vocal fold models are constructed with two different fiber orientations in the conus elasticus: the superior-inferior direction and the anterior-posterior direction. Flow-structure interaction simulations are conducted at different subglottal pressures to investigate the effects of fiber orientation in the conus elasticus on vocal fold vibrations, aerodynamic and acoustic measures of voice production. The results reveal that including the realistic fiber orientation (superior-inferior) in the conus elasticus yields smaller stiffness and larger deflection in the coronal plane at the junction of the conus elasticus and ligament and subsequently leads to a greater vibration amplitude and larger mucosal wave amplitude of the vocal fold. The smaller coronal-plane stiffness also causes a larger peak flow rate and higher skewing quotient. Furthermore, the voice generated by the vocal fold model with a realistic conus elasticus has a lower fundamental frequency, smaller first harmonic amplitude, and smaller spectral slope.

Characterisation of human posterior rectus sheath reveals mechanical and structural anisotropy

BackgroundOur work aims to investigate the mechanical properties of the human posterior rectus sheath in terms of its ultimate tensile stress, stiffness, thickness and anisotropy. It also aims to assess the collagen fibre organisation of the posterior rectus sheath using Second-Harmonic Generation microscopy. MethodsFor mechanical analysis, twenty-five fresh-frozen samples of posterior rectus sheath were taken from six different cadaveric donors. They underwent uniaxial tensile stress testing until rupture either in the transverse (n = 15) or longitudinal (n = 10) plane. The thickness of each sample was also recorded using digital callipers. On a separate occasion, ten posterior rectus sheath samples and three anterior rectus sheath samples underwent microscopy and photography to assess collagen fibre organisation. Findingssamples had a mean ultimate tensile stress of 7.7 MPa (SD 4.9) in the transverse plane and 1.2 MPa (SD 0.8) in the longitudinal plane (P < 0.01). The same samples had a mean Youngs modulus of 11.1 MPa (SD 5.0) in the transverse plane and 1.7 MPa (SD 1.3) in the longitudinal plane (P < 0.01). The mean thickness of the posterior rectus sheath was 0.51 mm (SD 0.13). Transversely aligned collagen fibres could be identified within the posterior sheath tissue using Second-Harmonic Generation microscopy. InterpretationThe posterior rectus sheath displays mechanical and structural anisotropy with greater tensile stress and stiffness in the transverse plane compared to the longitudinal plane. The mean thickness of this layer is around 0.51 mm – consistent with other studies. The tissue is constructed of transversely aligned collagen fibres that are visible using Second-Harmonic Generation microscopy.

OC-122 CHARACTERISATION OF HUMAN POSTERIOR RECTUS SHEATH REVEALS MECHANICAL AND STRUCTURAL ANISOTROPY

Abstract Background Our work investigated the mechanical properties of the posterior rectus sheath (PRS) in terms of its ultimate tensile stress (UTS), stiffness, thickness and anisotropy as well as assess the collagen fibre organisation of the PRS using Second-Harmonic Generation (SHG) microscopy. Methods For mechanical analysis, twenty-five fresh-frozen PRS samples of were taken from six different cadaveric donors. They underwent uniaxial tensile stress testing until rupture either in the transverse (n=15) or longitudinal (n=10) plane. The thickness of each sample was also recorded using digital callipers. On a separate occasion, ten PRS samples and three anterior rectus sheath samples underwent SHG microscopy and photography to assess collagen fibre organisation. Results PRS samples had a mean UTS of 7.7MPa (SD 4.9) in the transverse plane and 1.2 MPa (SD 0.8) in the longitudinal plane (P&amp;lt;0.01). The same samples had a mean Youngs modulus of 11.1 MPa (SD 5.0) in the transverse plane and 1.7 MPa (SD 1.3) in the longitudinal plane (P&amp;lt;0.01). The mean thickness of the posterior rectus sheath was 0.51mm (SD 0.13). Collagen fibres within the tissue could be identified with SHG microscopy, generally aligned transversely. Conclusion The PRS displayed mechanical and structural anisotropy with greater tensile stress and stiffness in the transverse plane compared to the longitudinal plane. The mean thickness of this layer is around 0.51mm – consistent with other studies. The tissue is constructed of transversely aligned collagen fibres that are visible using SHG microscopy.

Dynamic response of a space flexible arm with a moving mass

The dynamic characteristic of a space rotating flexible arm with moving mass were investigated. The space arm with moving mass can rotate around the fixed end in horizontal and vertical planes simultaneously. And the lateral deflections of the arm in the two planes were considered. The equations of the structure were derived by the Lagrange’s equation with the assumed mode method. And a system of binary second order linear differential equations is gotten. Based on the central difference method, a conditionally stable algorithm for solving the equations is established. Due to the coupling of lateral displacements of the arm in horizontal and vertical planes, the increase of the angular velocity in one plane will increase the lateral displacements in the other plane. When the angle between the arm and the horizontal plane increases, the component of gravity along the normal direction of the beam will decrease, resulting in a decrease in lateral displacements in vertical plane, however, it will lead to a decrease in stiffness in horizontal plane and thus an increase in lateral displacements. Compared with moving mass, moving load ignores the influence of inertial force, so the calculation results of moving mass and moving load are different. The conclusions provide calculation basis for the design of similar structures.

New possibilities to reduce wheel and rail wear in the operation of metro wagons on curved track with small curve radii without considering propulsion and braking systems

This paper analyses the parameters relevant to the operation of underground cars in traffic on straight and curved tracks with small curve radii. Current knowledge of non-linear lateral dynamics of rail vehicles and the specialist computer programme Vi-Rail were used to build models and perform simulation calculations. A solution was proposed to enable passive control of wheelsets with very high guiding stiffnesses, without the need for systems to force the axles of the wheelsets to align radially in a curved track. This effect was achieved by varying the guidance stiffness in the horizontal plane of the frame of each bogie. The adopted course of action offers simplicity of solution, low manufacturing costs, high critical speed on straight track and extended service life of the metro wagons resulting from reduced mechanical wear of wheels and rails. A multi-criteria evaluation was carried out, confirming improved bogie controllability and reduced impact of the metro wagon wheelsets on the curved track. Comparisons were made of the design volumes for metro model wagons with bogies with symmetric and unsymmetric axleguide stiffness arrangements of the wheelsets.

Regional variation in the mechanical properties of the skeletal muscle

Regional mechanics of skeletal muscle were investigated from equibiaxial testing in vitro on tissue samples. Samples were collected in three excising zones in transversal direction to the myofibers. Thus, the transverse plane stiffness, likely to be dictated by extracellular matrix collagen (ECM), was studied. For that, distal, middle, and proximal samples of healthy brachial biceps of rats have been tested. Data was used to generate the material parameters of the first order Ogden constitutive model at these different zones of skeletal muscle. In addition to having a nonlinear mechanical behavior, the analysis of the material parameters of the model showed that the stiffness value of the skeletal muscle tissue may on average have doubled depending on the collected sample location (p < 0.001). Furthermore, it was also shown that during the tests, when the storage temperature of the samples increases from 22 °C to 37 °C, the stiffness of the muscle tissue becomes more important (p < 0.05), which may be due to the rigor mortis phenomenon. Thus, these results contribute to investigating the regional change of mechanical properties of skeletal muscle, particularly those of ECM that play a major role in stiffness tissue, which is essential for the development of accurate computational models.

Understanding Modulation of Ankle Stiffness During Stance Phase of Walking on Different Ground Surfaces

Understanding how human ankle mechanics are modulated when walking on various ground surfaces (e.g., soft and unstable ground surfaces) would help the development of controllers of lower extremity robots (e.g., prostheses and exoskeletons) mimicking human ankle behaviors. With this goal in mind, this study investigated how ankle stiffness in the sagittal plane is modulated throughout the stance phase of walking over different ground surfaces. A robotic platform, capable of simulating different mechanical environments, was used to quantify ankle stiffness in the sagittal plane during walking over compliant and rigid surfaces. The group average results of 10 healthy individuals showed that ankle stiffness increased with the progression of stance phase of walking but there was no significant environmental effect on the stiffness modulation. Further investigation into each individual subject revealed that surface compliance had an impact on the modulation of ankle stiffness in the later stance phase, which was significantly correlated with center of pressure position regardless of the surface condition (Pearson correlation coefficient: ∼0.93). Implications of the observed results for the development of continuous impedance controllers for lower extremity robots are discussed.

Free vibration analysis of curved lattice sandwich beams

In this paper, the effects of initial curvature and lattice core shape on the bending vibration of sandwich beams are investigated. The three-dimensional (3D) sandwich beam is simulated by combining a two-dimensional (2D) cross-sectional analysis with a one-dimensional (1D) nonlinear beam analysis. The sandwich beam is composed of two identical isotropic faces covering a lattice core. Four different lattice core structures are used to take into account the effect of core unit cell shape on the dynamic properties of the sandwich beam. The nonlinear governing equations of the sandwich beam are Discretized using a time-space scheme. Numerical results show that the lattice unit cell shape affects both in-plane and out of plane stiffness values and hence changes the dynamic behavior of the beam. Furthermore, it is observed that by changing the density ratio of the beam, modes veer away from each other at a specific value of density ratio for specific unit cell types. Moreover, the initial curvature of the beam is shown to affect the dynamics of the beam especially lower modes. Finally, it is obtained that the dynamics of the beam is different when it is initially curved or curved due to an applied end follower moment.

Experimental Study on Damage and Degradation of Structure Plane in Rock Mass under Cyclic Shear Load

By summarizing the generalized model of the structural plane in a rock mass under a cyclic shear load and influencing factors of dynamic mechanical properties of the structural plane, the mechanism of structural plane damage and degradation is discussed, and the evolution of damage to the structural plane is ascertained from cyclic shear tests by using structural planes with different undulating angles. Based on model tests and previous studies, nonlinear constitutive equations considering the effect of structural plane damage and degradation are presented. The effects of the initial undulating angle, amplitude of the cyclic shear load, and cycle times on the strength of the structural plane, as well as the degeneration process of structural plane stiffness under a cyclic shear load, are taken into consideration in the equations. The applicability of the above-mentioned constitutive equations is analyzed with a corresponding program compiled in the FISH language in the Universal Distinct Element Code (UDEC). The UDEC numerical simulation results are verified with ones from the model test. The achievements presented in this paper are of great significance to theoretical study of the mechanical behaviors of rock masses under cyclic shear loads and to project practice.

The Functionality Verification through Pilot Human Subject Testing of MyFlex-δ: An ESR Foot Prosthesis with Spherical Ankle Joint

Most biomechanical research has focused on level-ground walking giving less attention to other conditions. As a result, most lower limb prosthesis studies have focused on sagittal plane movements. In this paper, an ESR foot is presented, of which five different stiffnesses were optimized for as many weight categories of users. It is characterized by a spherical ankle joint, with which, combined with the elastic elements, the authors wanted to create a prosthesis that gives the desired stiffness in the sagittal plane but at the same time, gives flexibility in the other planes to allow the adaptation of the foot prosthesis to the ground conditions. The ESR foot was preliminarily tested by participants with transfemoral amputation. After a brief familiarization with the device, each participant was asked to wear markers and to walk on a sensorized treadmill to measure their kinematics and kinetics. Then, each participant was asked to leave feedback via an evaluation questionnaire. The measurements and feedback allowed us to evaluate the performance of the prosthesis quantitatively and qualitatively. Although there were no significant improvements on the symmetry of the gait, due also to very limited familiarization time, the participants perceived an improvement brought by the spherical ankle joint.

Effect of pretension on the performance of cable bolts and its optimisation in underground coal mines with various geological conditions

Pretension is the pre-added axial tensile force on fully grouted bolt systems, which include rock bolts and cable bolts. Although a series of studies via lab testing and analytical modelling proved the importance of pretension in cable bolts, there is no systematic analysis to guide the optimal pretension values to be applied on cable bolts in different engineering geological conditions. Complicated geological conditions, such as anisotropic in-situ stress, bedding plane detachment and country rock deformation, cannot be fully represented in the lab or analytical work. In addition, field scale numerical models to investigate cable bolt performance and its interaction with various geological conditions are rare. This paper analyses the effect of pretension on the performance of cable bolts in underground coal mines via field scale numerical models, with considering different geological conditions (in-situ stress, bedding plane stiffness and rock mass properties). Numerical models were developed based on a case study mine in Australia with challenging ground conditions. The in-situ stress, properties of claystone and bedding planes are considered critical variables to be analysed. The results show higher pretension contributes to higher force along the cable bolt. Neutral points, where shear force in grout materials is zero, are used to describe the pretension-induced stress redistribution on cable bolts. Pretension also has a positive effect on roof and bedding plane management, resulting in a more stable roof condition. In addition, high pretension and high in-situ stress are more likely to result in cable-grout (CG) interface failure since the relative vertical displacement difference between cable bolts and the surrounding rock mass is higher. Once CG interface failure is generated, the pretension effect turns out to be negative, leading to severe roof sagging and bedding plane aperture. This paper provides a guide to the application of pretension in coal mining.

ANALYSIS OF A MULTI-STOREYED RESIDENTIAL BUILDING WITH SHEAR WALL AT CORNER

Shear wall systems are one of the most commonly used lateral load resisting system in high rise residential buildings. They resist in-plane loads that are applied along its height, Shear wall has very high in plane stiffness and strength which could be used to simultaneously resist large horizontal loads and support vertical or gravity loads making them quite advantageous in many structural engineering applications. It was observed that Multi- storeyed R.C.C. Buildings with shear wall is economical as compared to without shear wall. The Articles deals with comparative study of G+15 Storey building in Zone IV is presented with some preliminary investigation which is analysed shear wall at corner to determine parameter like axial load and moments. This analysis is done by using Software package STADD-pro. The buildings are modelled with floor area of 256 sqm (16m x16m) with 4 bays along 16 m span each 4 m. and 4 bays along the 16 m span each 4 m. The design is carried out using STAAD.PRO software. The main aim of the present work is therefore to make a comparative study of structural system and orientation with the shear wall at corner. There are lots of literatures available on design and analysis of the shear wall system. However, the decision about the location of shear wall in multi-storey building is not much discussed in any literatures. A study on a residential building with shear wall at corner was analysed. Keywords: Shear wall, Lateral forces, Staad Pro, Multi- storeyed.

The Deep Hip Muscles are Unlikely to Stabilize the Hip in the Sagittal Plane During Walking: A Joint Stiffness Approach.

This study determined the contribution of the deep hip muscles to hip stability. Hip stability was defined as rotational hip stiffness in the sagittal plane, which was calculated for walking trials for 12 participants via an electromyography (EMG)-informed neuromusculoskeletal model which included all 22 hip spanning muscles. Three model configurations which differed in deep hip muscle excitations but had identical excitations for all other muscles were compared: (1) deep hip muscles informed by intramuscular EMG measurements (assisted activation); (2) deep hip muscles with simulated zero activation (no activation); (3) deep hip muscles with simulated maximal activation (maximal activation). Sagittal plane rotational hip stiffness across the gait cycle was compared between the three model configurations using a within-participant analysis of variance via statistical parametric mapping (p < 0.05). Compared to the assisted activation configuration, hip stiffness (mean (95% confidence interval)) was 0.8% (0.7 to 0.9) lower in the no activation configuration, and 3.2% (3.0 to 3.4) higher in the maximal activation configuration. Regardless of activation level, deep hip muscles contributed little to sagittal plane rotational hip stiffness, which casts doubt on their assumed function as hip stabilizers. The merit of targeted deep hip muscle strengthening to improve hip stability in rehabilitation programs remains unclear.

Multiplanar Stiffness of Commercial Carbon Composite Ankle-Foot Orthoses.

The mechanical properties of an ankle-foot orthosis (AFO) can impact how a user's movement is either restricted or augmented by the device. However, standardized methods for assessing stiffness properties of AFOs are lacking, posing a challenge for comparing between devices and across vendors. Therefore, the purpose of this study was to quantify the rotational stiffness of thirteen commercial, nonarticulated, carbon composite ankle-foot orthoses. A custom, instrumented test fixture, for evaluating mechanical properties in rotating exoskeletons (EMPIRE), deflected an AFO through 20 deg of plantar/dorsiflexion motion about a specified, but adjustable, ankle axis. Sagittal, frontal, and transverse plane rotational stiffness were calculated, and reliability was assessed between cycles, sessions, and testers. The EMPIRE demonstrated good-to-excellent reliability between testers, sessions, and cycles (intraclass correlation coefficients all ≥0.95 for sagittal plane stiffness measures). Sagittal plane AFO stiffness ranged from 0.58 N·m/deg to 3.66 N·m/deg. AFOs with a lateral strut demonstrated frontal plane stiffnesses up to 0.71 N·m/deg of eversion while those with a medial strut demonstrated frontal plane stiffnesses up to 0.53 N·m/deg of inversion. Transverse plane stiffnesses were less than 0.30 N·m/deg of internal or external rotation. These results directly compare AFOs of different models and from different manufacturers using consistent methodology and are intended as a resource for clinicians in identifying a device with stiffness properties for individual patients.