scholarly journals THE SIMULATION OF MECHANICAL STIMULATION EFFECT ON BONE ELASTICITY LIMIT BASED ON FINITE ELEMENT METHOD (FEM)

2021 ◽  
Vol 83 (3) ◽  
pp. 21-27
Author(s):  
Khusnul Yakin ◽  
Ita Setyaningsih ◽  
Nurani Indha Rusmana ◽  
Mohammad Tirono ◽  
Rofiqul Umam
Keyword(s):  
Bone Density ◽  
Strain Rate ◽  
Mechanical Stimulation ◽  
Stress And Strain ◽  
Mechanical Stimuli ◽  
Elasticity Limit ◽  
Bone Properties ◽  
Strain And Strain Rate ◽  
Reversal Phase ◽  
The Difference

Osteoporosis is a disease  affecting bones which is characterized by decreased bone density;  bones become porous and  susceptible to fractures. Osteoporosis occurs because of an imbalance during bone remodeling phase between resorption and formation processes. This study aims to simulate the effects of mechanical stimulations on the femoral bone elasticity limit. It is hoped that these mechanical stimuli can provide information on bone elasticity limits. Initially, we constructed the femur in two layers using triangular elements. Then we entered the bone properties (Young’s modulus and Poisson’s ratio) based on the age of the femur. After that we  calculated the value of the stress, strain, and strain rate in the reversal phase. Next, we calculated the  bone density using the thermodynamic equation and calculation of the bone elasticity limit using particle swarm optimization (PSO) methods. The value of stress and strain caused by walking is higher than the value of stress and strain when standing still. In this case, the difference in activity results an increase in stress by 33.82% and an increase in strain and strain rate by 34.57%. Based on these simulation results, it can be concluded that mechanical stimulation can increase the limit of bone elasticity to 2.99% in cortical bone and 0.975% in trabecular bone. Bone elasticity limit can be used to determine the level of osteoporosis that occurs. The higher value of the bone elasticity, the smaller the possibility of osteoporosis.

Effects of Foot Strike and Step Frequency on Achilles Tendon Stress During Running

2016 ◽  
Vol 32 (4) ◽  
pp. 365-372 ◽  
Author(s):  
Michael Lyght ◽  
Matthew Nockerts ◽  
Thomas W. Kernozek ◽  
Robert Ragan
Keyword(s):  
Strain Rate ◽  
Achilles Tendon ◽  
Musculoskeletal Model ◽  
Stress And Strain ◽  
Step Frequency ◽  
Stress Strain ◽  
Strain And Strain Rate ◽  
Subject Specific ◽  
Foot Strike ◽  
Crosssectional Area

Achilles tendon (AT) injuries are common in runners. The AT withstands high magnitudes of stress during running which may contribute to injury. Our purpose was to examine the effects of foot strike pattern and step frequency on AT stress and strain during running utilizing muscle forces based on a musculoskeletal model and subject-specific ultrasound-derived AT crosssectional area. Nineteen female runners performed running trials under 6 conditions, including rearfoot strike and forefoot strike patterns at their preferred cadence, +5%, and –5% preferred cadence. Rearfoot strike patterns had less peak AT stress (P < .001), strain (P < .001), and strain rate (P < .001) compared with the forefoot strike pattern. A reduction in peak AT stress and strain were exhibited with a +5% preferred step frequency relative to the preferred condition using a rearfoot (P < .001) and forefoot (P=.005) strike pattern. Strain rate was not different (P > .05) between step frequencies within each foot strike condition. Our results suggest that a rearfoot pattern may reduce AT stress, strain, and strain rate. Increases in step frequency of 5% above preferred frequency, regardless of foot strike pattern, may also lower peak AT stress and strain.

scholarly journals Reduction of left atrial strain and strain rate during conduit phase as the earliest marker of left ventricular diastolic disfunction

2021 ◽  
Vol 22 (Supplement_1) ◽  
Author(s):  
A Savelev ◽  
OV Solovev ◽  
MA Baturova ◽  
YV Shubik
Keyword(s):  
Strain Rate ◽  
Left Atrial ◽  
Area Under The Curve ◽  
Left Ventricular ◽  
Left Atrial Strain ◽  
Single Plane ◽  
Strain And Strain Rate ◽  
Significant Difference ◽  
The Difference ◽  
Grade 3

Abstract Funding Acknowledgements Type of funding sources: None. Left atrial (LA) functional abnormalities, including LA strain (LAS) and strain rate (LASR) reduction, are observed in patients with left ventricular diastolic disfunction (LVDD). However, the degree of reduction at different stages of LVDD is not fully clarified. We aimed to assess the interdependence between LAS and LASR parameters and LVDD grades in subjects of advanced age with preserved ejection fraction (EF). Material and methods Consecutive patients, who underwent echocardiography within 12 months, were screened and included into the study in case of age older than 65 years, preserved EF, sinus rhythm at the time of study and preserved dataset of sufficient quality for speckle tracking analysis. LAS and LASR parameters, including LAS and peak LASR during reservoir, conduit, and contractile phases were calulated with single plane apical 4-chamber view assessment. One-way ANOVA analysis with Bonferroni correction was used to assess the difference between groups. Results Among 153 patients (mean age 74 ± 7 years; 105 female, mean EF 64 ± 5%) included in the study there were 38 patients with no evidence of LVDD, 67 with LVDD grade 1, 40 with LVDD grade 2, and 5 with LVDD grade 3. The values of LAS and LASR parameters for these groups are summarized in Table. All parameters were significantly reduced in grade 2 and 3 LVDD patients comparing to the patients with no LVDD. Contractile phase LAS and LASR were slightly higher in grade 1 than in no LVDD patients. Reservoir and conduit phase LAS and LASR were lower in grade 1 LVDD comparing to no LVDD, but only for conduit phase parameters the difference was significant. In ROC analysis for conduit phase LAS and LASR to be associated with the presence of LVDD of any grade the  area under the curve was 0,707 (p &lt; 0.001) and 0,742 (p &lt; 0.001) respectively. Conclusion Impaired LA function is seen in patients with LVDD. Whereas measurements characterizing LA reservoir and contractile functions demonstrate significant decrease at advanced stages of LVDD, conduit function is significantly reduced at grade 1 LVDD, providing the possibility for early detection of LVDD. Group LAS (%) LASR (1/sec) reservoir conduit contractile reservoir conduit contractile No LVDD, n = 38 29,7 ± 9,3 †‡ 15,1 ± 6,6 §†‡ 14,6 ± 5,4 †‡ 1,28 ± 0,37 †‡ 1,18 ± 0,44 §† 1,68 ± 0,60 †‡ Grade 1, n = 69 28,6 ± 8,9 †‡ 11,6 ± 6,2 ƒ 17,0 ± 5,7 †‡ 1,23 ± 0,43 ‡ 0,90 ± 0,38 ƒ 1,99 ± 0,71 †‡ Grade 2, n = 40 19,1 ± 7,1 ƒ§ 9,2 ± 4,5 ƒ 9,9 ± 4,4 ƒ§ 0,87 ± 0,26 ƒ§ 0,72 ± 0,27 ƒ 1,07 ± 0,44 ƒ§ Garde 3, n = 5 13,8 ± 3,6 ƒ§ 7,7 ± 2,5 ƒ 6,1 ± 2,2 ƒ§ 0,8 ± 0,29 ƒ 0,75 ± 0,28 0,67 ± 0,27 ƒ§ Significant difference (p &lt; 0,05): ƒ – with No LVDD, § – with Grade 1 LVDD, † – with Grade 2 LVDD, ‡ – with Grade 3 LVDD

scholarly journals Improving the workability of materials during the dieless drawing processes by multi-pass incremental deformation

2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Andrij Milenin ◽  
Tsuyoshi Furushima ◽  
Peihua Du ◽  
Valeriy Pidvysots’kyy
Keyword(s):  
Strain Rate ◽  
Pure Copper ◽  
Rate Sensitivity ◽  
Experimental Tests ◽  
Heating System ◽  
Strain And Strain Rate ◽  
Dieless Drawing ◽  
Simultaneous Modeling ◽  
The Difference ◽  
Material Ductility

Abstract The paper explores the new method of improving the workability of materials in the dieless drawing processes. The proposed method is based on the implementation of a multi-pass incremental deformation. Moreover, in each pass, strain and strain rate sensitivity of flow stress should be positive and significant. An approach based on the finite element calculation of instability coefficient of plastic deformation and simultaneous modeling of material ductility were applied for prediction of the workability. Two dieless drawing processes have been investigated. The difference was related to the heating system—induction heating and laser heating. FE simulations and experimental tests for three materials, two magnesium alloys (MgCa0.8 and MgNi19) and pure copper were performed. It was shown that the most effective increase in workability by multi-pass deformation can be achieved using laser dieless drawing. This is possible due to the shorter heating area and, as a consequence, the larger strain rate, which leads to better stability of the deformation process.

scholarly journals Gradients of strain and strain rate in the hollow muscular organs of soft-bodied animals

2010 ◽  
Vol 6 (4) ◽  
pp. 482-485 ◽  
Author(s):  
Joseph T. Thompson ◽  
Kari R. Taylor ◽  
Christopher Gentile
Keyword(s):  
Strain Rate ◽  
Outer Surface ◽  
Circumferential Strain ◽  
Circular Muscle ◽  
The Body ◽  
Muscle Fibres ◽  
Cylindrical Shape ◽  
Strain And Strain Rate ◽  
Inner Surface ◽  
The Difference

The cylindrical shape of soft-bodied invertebrates is well suited to functions in skeletal support and locomotion, but may result in a previously unrecognized cost—large non-uniformities in muscle strain and strain rate among the circular muscle fibres of the body wall. We investigated such gradients of strain and strain rate in the mantle of eight long-finned squid Doryteuthis pealeii and two oval squid Sepioteuthis lessoniana . Transmural gradients of circumferential strain were present during all jets ( n = 312); i.e. for a given change in the circumference of the outer surface of the mantle, the inner surface experienced a greater proportional change. The magnitude of the difference increased with the amplitude of the mantle movement, with circular muscle fibres at the inner surface of the mantle experiencing a total range of strains up to 1.45 times greater than fibres at the outer surface during vigorous jets. Differences in strain rate between the circular fibres near the inner versus the outer surface of the mantle were also present in all jets, with the greatest differences occurring during vigorous jetting. The transmural gradients of circumferential strain and strain rate we describe probably apply not only to squids and other coleoid cephalopods, but also to diverse soft-bodied invertebrates with hollow cylindrical or conical bodies and muscular organs.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

The effect of low magnitude mechanical stimulation (LMMS) on bone density in patients with Rett syndrome: A pilot and feasibility study

2014 ◽  
Vol 7 (2) ◽  
pp. 167-178 ◽  
Author(s):  
Sarah Y. Afzal ◽  
Anna R. Wender ◽  
Mary D. Jones ◽  
Ellen B. Fung ◽  
Elaine L. Pico
Keyword(s):  
Bone Density ◽  
Rett Syndrome ◽  
Feasibility Study ◽  
Mechanical Stimulation ◽  
Low Magnitude

scholarly journals Application of the Strain Compensation Model and Processing Maps for Description of Hot Deformation Behavior of Metastable β Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2021
Author(s):  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Aneta Łukaszek-Sołek ◽  
Krystian Zyguła ◽  
Marek Wojtaszek
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Microstructural Analysis ◽  
Calculated Data ◽  
Processing Temperature ◽  
Processing Maps ◽  
Compression Tests ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and strain rate range of 0.01–100 s−1. The strain compensated constitutive model was developed using the Arrhenius-type equation. The high correlation coefficient (R) as well as low average absolute relative error (AARE) between the experimental and the calculated data confirmed a high accuracy of the developed model. The dynamic material modeling in combination with the Prasad stability criterion made it possible to generate processing maps for the investigated processing temperature, strain and strain rate ranges. The high material flow stability under investigated deformation conditions was revealed. The microstructural analysis provided additional information regarding the flow behavior and predominant deformation mechanism. It was found that dynamic recovery (DRV) was the main mechanism operating during the deformation of the investigated β titanium alloy.

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