Stretching of capsules in an elongation flow, a route to constitutive law

2015 ◽  
Vol 767 ◽  
Author(s):  
C. de Loubens ◽  
J. Deschamps ◽  
G. Boedec ◽  
M. Leonetti
Keyword(s):  
Elastic Modulus ◽  
Poisson Ratio ◽  
Elastic Shell ◽  
Cross Flow ◽  
Elongation Rate ◽  
Constitutive Law ◽  
Geometrical Analysis ◽  
Shear Elastic Modulus ◽  
Elongation Flow ◽  
Set Up

AbstractSoft bio-microcapsules are drops bounded by a thin elastic shell made of cross-linked proteins. Their shapes and their dynamics in flow depend on their membrane constitutive law characterized by shearing and area-dilatation resistance. The deformations of such capsules are investigated experimentally in planar elongation flows and compared with numerical simulations for three bidimensional models: Skalak, neo-Hookean and generalized Hooke. An original cross-flow microfluidic set-up allows the visualization of the deformed shape in the two perpendicular main fields of view. Whatever the elongation rate, the three semi-axis lengths of the ellipsoid fitting the experimental shape are measured up to 180 % of stretching of the largest axis. The geometrical analysis in the two views is sufficient to determine the constitutive law and the Poisson ratio of the membrane without a preliminary knowledge of the shear elastic modulus$G_{s}$. We conclude that the membrane of human serum albumin capsules obeys the generalized Hooke law with a Poisson ratio of 0.4. The shear elastic modulus is then determined by the combination of numerical and experimental variations of the Taylor parameter with the capillary number.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

An Evolutionary Multi-Objective Optimization Approach to the Topology Optimization of Auxetic Structures

2002 ◽  
Author(s):  
Ashraf O. Nassef
Keyword(s):  
Topology Optimization ◽  
Elastic Modulus ◽  
Finite Elements ◽  
Multiobjective Optimization ◽  
Poisson Ratio ◽  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Finite Elements Analysis ◽  
Multi Objective ◽  
Auxetic Structures

Auxetic structures are ones, which exhibit an in-plane negative Poisson ratio behavior. Such structures can be obtained by specially designed honeycombs or by specially designed composites. The design of such honeycombs and composites has been tackled using a combination of optimization and finite elements analysis. Since, there is a tradeoff between the Poisson ratio of such structures and their elastic modulus, it might not be possible to attain a desired value for both properties simultaneously. The presented work approaches the problem using evolutionary multiobjective optimization to produce several designs rather than one. The algorithm provides the designs that lie on the tradeoff frontier between both properties.

scholarly journals Effect of Static Stretching with Superficial Cooling on Muscle Stiffness

2018 ◽  
Vol 02 (05) ◽  
pp. E142-E147 ◽  
Author(s):  
Masatoshi Nakamura ◽  
Ryo Hirabayashi ◽  
Shuhei Ohya ◽  
Takafumi Aoki ◽  
Daichi Suzuki ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Random Order ◽  
Acute Effect ◽  
Muscle Stiffness ◽  
Cooling Condition ◽  
Medial Gastrocnemius ◽  
Static Stretching ◽  
Shear Elastic Modulus ◽  
And Control ◽  
Healthy Males

AbstractThis study aimed to clarify the acute effect of static stretching (SS) with superficial cooling on dorsiflexion range of motion (DF ROM) and muscle stiffness. Sixteen healthy males participated in the cooling condition and a control condition in a random order. The DF ROM and the shear elastic modulus of medial gastrocnemius (MG) in the dominant leg were measured during passive dorsiflexion. All measurements were performed prior to (PRE) and immediately after 20 min of cooling or rested for 20 min (POST), followed by 2 min SS (POST SS). In cooling condition, DF ROM at POST and POST SS were significantly higher than that at PRE and DF ROM at POST SS was significantly higher than that at POST. In addition, the shear elastic modulus at POST was significantly higher than that at PRE and the shear elastic modulus at POST SS was significantly lower than those at PRE and POST. However, there were no significant differences in the percentage changes between PRE and POST SS between the cooling and control conditions. Our results showed that effects of SS with superficial cooling on increases in ROM and decrease in muscle stiffness were no more beneficial than those of SS alone.

First-Order Frequency Effects in Supersonic Panel Flutter of Finite Cylindrical Shells

1973 ◽  
Vol 40 (2) ◽  
pp. 464-470
Author(s):  
M. Holt ◽  
T. M. Lee
Keyword(s):  
Mach Number ◽  
Elastic Shell ◽  
Order Effect ◽  
Aerodynamic Load ◽  
Panel Flutter ◽  
Thin Cylindrical Shell ◽  
First Order ◽  
Flutter Boundary ◽  
Shell Equation ◽  
Set Up

An improved calculation of the supersonic panel flutter characteristics of a thin cylindrical shell of finite length is presented. The aerodynamic load is determined with account taken of first-order terms in vibration frequency, and when this is introduced into the elastic shell equation an integro differential equation results. An equivalent eigenvalue problem is set up by applying Galerkin’s method to this equation. The flutter boundary, for given Mach number and circumferential mode n, corresponds to the shell thickness ratio at which the real part of any one of the eigenvalues first becomes non-negative. It is found that the most severe flutter condition, for given Mach number, occurs for a circumferential mode n = 7. The present calculations exclude second-order frequency terms in the elastic part of the flutter equation, even though they may have a first-order effect. A subsequent calculation referred to here shows that these terms indeed have no significant influence on the first-order analysis.

scholarly journals Evaluation Method of Granite Multiscale Mechanical Properties Based on Nanoindentation Technology

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Man Lei ◽  
Fa-ning Dang ◽  
Haibin Xue ◽  
Mingming He
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Uniaxial Compression ◽  
Compression Test ◽  
Evaluation Method ◽  
Poisson Ratio ◽  
Nanoindentation Test ◽  
Uniaxial Compression Test ◽  
Displacement Curve ◽  
Mineral Contents

In order to study the mechanical properties of granite at the micro- and nanoscale, the load-displacement curve, residual indentation information, and component information of the quartz, feldspar, and mica in granite were obtained using a nanoindentation test, a scanning electron microscope (SEM), and X-ray diffraction (XRD). The elastic modulus and the hardness of each component of the granite were obtained through statistical analysis. Treating rock as a composite material, the relation between the macro- and microscopic mechanical properties of rock was established through the theory of micromechanical homogenization. The transition from micromechanical parameters to macromechanical parameters was realized. The equivalent elastic modulus and Poisson’s ratio of the granite were obtained by the Self-consistent method, the Dilute method, and the Mori-Tanaka method. Compared with the elastic modulus and the Poisson ratio of granites measured by a uniaxial compression test and the available data, the applicability of the three methods were analyzed. The results show that the elastic modulus and hardness of the quartz in the granite is the largest, the feldspar is the second, the mica is the smallest. The main mineral contents in granite were analyzed using the semiquantitative method by XRD and the rock slice identification test. The elastic modulus and the Poisson ratio of granite calculated by three linear homogenization methods are consistent with those of the uniaxial compression test. After comparing the calculation results of the three methods, it is found that the Mori-Tanaka method is more suitable for studying the mechanical properties of rock materials. This method has an important theoretical significance and practical value for studying the quantitative relationship between macro- and micromechanical indexes of brittle materials. The research results provide a new method and an important reference for studying the macro-, micro-, and nanomechanical properties of rock.

scholarly journals Post-Operative Assessment of Ulnar Nerve Tension Using Shear-Wave Elastography

2021 ◽  
Vol 13 (3) ◽  
pp. 469-476
Author(s):  
Sebastien Durand ◽  
Wassim Raffoul ◽  
Thierry Christen ◽  
Nadine Pedrazzi
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Ulnar Nerve ◽  
Shear Wave Elastography ◽  
Elbow Flexion ◽  
Ulnar Nerve Compression ◽  
Nerve Decompression ◽  
Shear Elastic Modulus ◽  
Anterior Transposition ◽  
Operative Assessment

Background: Ulnar nerve compression at the elbow level is the second-most common entrapment neuropathy. The aim of this study was to use shear-wave elastography for the quantification of ulnar nerve elasticity in patients after ulnar nerve decompression with anterior transposition and in the contralateral non-operative side. Method: Eleven patients with confirmed diagnosis and ulnar nerve decompression with anterior transposition were included and examinations were performed on an AixplorerTM ultrasound system (Supersonic Imagine, Aix-en-Provence, France). Results: We observed significant differences at 0-degree (p < 0.001), 45-degree (p < 0.05), 90-degree (p < 0.01) and 120-degree (p < 0.001) elbow flexion in the shear elastic modulus of the ulnar nerve in the operative and non-operative sides. There were no statistically significant differences between the elasticity values of the ulnar nerve after transposition at 0-degree elbow flexion and in the non-operative side at 120-degree elbow flexion (p = 0.39), or in the ulnar nerve after transposition at 120-degree elbow flexion and in the non-operative side at 0-degree elbow flexion (p = 0.09). Conclusion: Shear-wave elastography has the potential to be used postoperatively as a method for assessing nerve tension noninvasively by the estimation of mechanical properties, such as the shear elastic modulus.

scholarly journals Shoulder horizontal abduction stretching effectively increases shear elastic modulus of pectoralis minor muscle

2017 ◽  
Vol 26 (7) ◽  
pp. 1159-1165 ◽  
Author(s):  
Jun Umehara ◽  
Masatoshi Nakamura ◽  
Kosuke Fujita ◽  
Ken Kusano ◽  
Satoru Nishishita ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Shear Elastic Modulus ◽  
Pectoralis Minor ◽  
Pectoralis Minor Muscle ◽  
Minor Muscle

Effect of Rest Duration Between Static Stretching on Passive Stiffness of Medial Gastrocnemius Muscle In Vivo

2020 ◽  
Vol 29 (5) ◽  
pp. 578-582
Author(s):  
Masatoshi Nakamura ◽  
Shigeru Sato ◽  
Ryosuke Kiyono ◽  
Nobushige Takahashi ◽  
Tomoichi Yoshida
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Repeated Measures ◽  
Shear Wave Elastography ◽  
Muscle Stiffness ◽  
Medial Gastrocnemius ◽  
Static Stretching ◽  
Shear Elastic Modulus ◽  
Before And After

Context: In clinical and sports settings, static stretching (SS) is usually performed to increase range of motion (ROM) and decrease passive muscle stiffness. Recently, the shear elastic modulus was measured by ultrasonic shear wave elastography as an index of muscle stiffness. Previous studies reported that the shear elastic modulus measured by ultrasound shear wave elastography decreased after SS, and the effects of SS on shear elastic modulus were likely affected by rest duration between sets of SS. Objective: To investigate the acute effects of SS with different rest durations on ROM and shear elastic modulus of gastrocnemius and to clarify whether the rest duration between sets of SS decreases the shear elastic modulus. Design: A randomized, repeated-measures experimental design. Setting: University laboratory. Participants: Sixteen healthy males volunteered to participate in the study (age 21.3 [0.8] y; height 171.8 [5.1] cm; weight 63.1 [4.5] kg). Main Outcome Measures: Each participant underwent 3 different rest interval durations during SS (ie, long rest duration: 90 s; normal rest duration: 30 s; and short rest duration: 10 s). This SS technique was repeated 10 times, thus lasting a total of 300 seconds with different rest durations in each protocol. The dorsiflexion ROM and shear elastic modulus were measured before and after SS. Results: Our results revealed that dorsiflexion ROM and shear elastic modulus were changed after 300-second SS; however, no effects of the rest duration between sets of SS were observed. Conclusions: In terms of decreasing the shear elastic modulus, clinicians and coaches should not focus on the rest duration when SS intervention is performed.

Change in Shear Elastic Modulus of Thigh Muscle by Changing Muscle Length Using Ultrasound Shear Wave Elastography in Beagle Dogs

2019 ◽  
Vol 32 (06) ◽  
pp. 454-459 ◽  
Author(s):  
Miki Shimizu ◽  
Yu Ito
Keyword(s):  
Elastic Modulus ◽  
Shear Wave ◽  
Vastus Lateralis ◽  
Muscle Length ◽  
Shear Wave Elastography ◽  
Biceps Femoris ◽  
Percentage Change ◽  
Thigh Muscle ◽  
Beagle Dogs ◽  
Shear Elastic Modulus

Objectives This study investigated the relationship between the change in the shear elastic modulus and the change in muscle length using ultrasound shear wave elastography. Study Design Four thigh muscles, cranial part of the sartorius, vastus lateralis, biceps femoris and semitendinosus muscles, of 21 pelvic limbs in 12 clinically healthy Beagle dogs were used. The muscle length was estimated using a radiograph and the flexed and extended positions of the coxofemoral and stifle joints, respectively. The shear elastic modulus (kPa) was measured in two joint positions using ultrasound shear wave elastography. Shear elastic modulus was expressed as median of 10 consecutive measurements. The percentage change of elastic modulus was calculated from the shear elastic modulus in elongated condition and pre-elongated condition of muscle. Results The elastic modulus of all muscles increased when the muscle was elongated. The shear elastic modulus for both joint positions and the percentage change of the shear elastic modulus (%) in cranial part of the sartorius were highest in all muscles. Intra-observer correlation coefficient (1.2) was 0.75 to 0.96 and intra-observer correlation coefficients (2.2) was 0.46 to 0.96. Conclusion This study revealed that the shear elastic modulus of muscle was changed by the change in muscle length and increased when the muscle was elongated. Ultrasound shear wave elastography can be used to assess the elastic properties of canine muscle.

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