scholarly journals Approaches for process and structural finite element simulations of braided ligament replacements

2016 ◽  
Vol 47 (3) ◽  
pp. 408-425 ◽  
Author(s):  
Thomas Gereke ◽  
Oliver Döbrich ◽  
Dilbar Aibibu ◽  
Jorg Nowotny ◽  
Chokri Cherif
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Process Model ◽  
Structural Model ◽  
Structural Parameters ◽  
Healing Process ◽  
Resorbable Polymers ◽  
Wide Range ◽  
Experimental Trials ◽  
Good Agreement

To prevent the renewed rupture of ligaments and tendons prior to the completed healing process, which frequently occurs in treated ruptured tendons, a temporary support structure is envisaged. The limitations of current grafts have motivated the investigation of tissue-engineered ligament replacements based on the braiding technology. This technology offers a wide range of flexibility and adjustable geometrical and structural parameters. The presented work demonstrates the possible range for tailoring the mechanical properties of polyester braids and a variation of the braiding process parameters. A finite element simulation model of the braiding process was developed, which allows the optimization of production parameters without the performance of further experimental trials. In a second modelling and simulation step, mechanical properties of the braided structures were virtually determined and compared with actual tests. The digital element approach was used for the yarns in the numerical model. The results show very good agreement for the process model in terms of braiding angles and good agreement for the structural model in terms of force-strain behaviour. With a few adaptions, the models can, thus, be applied to actual ligament replacements made of resorbable polymers.

Collapse of Tubes Under Combined Bending and Axial Compression Loads

2018 ◽  
Author(s):  
Shan Jin ◽  
Shuai Yuan ◽  
Yong Bai
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Axial Compression ◽  
Local Buckling ◽  
Practical Application ◽  
Buckling Modes ◽  
Combined Loads ◽  
Bending Loads ◽  
Good Agreement

In practical application, pipelines will inevitably experience bending and compression during manufacture, transportation and offshore installation. The mechanical behavior of tubes under combined axial compression and bending loads is investigated using experiments and finite element method in this paper. Tubes with D/t ratios in the range of 40 and 97 are adopted in the experiments. Then, the ultimate loads and the local buckling modes of tubes are studied. The commercial software ABAQUS is used to build FE models to simulate the load-shortening responses of tubes under combined loads. The results acquired from the ABAQUS simulation are compared with the ones from verification bending experiment, which are in good agreement with each other. The models in this paper are feasible to analyze the mechanical properties of tubes under combined axial compression and bending loads. The related results may be of interest to the manufacture engineers.

scholarly journals A Buckling Flexure-Based Force-Limiting Mechanism

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Jonathan Slocum ◽  
Kenneth Kamrin ◽  
Alexander Slocum
Keyword(s):  
Finite Element ◽  
Design Methodology ◽  
Structural Model ◽  
Cost Effective ◽  
Element Model ◽  
Single Shot ◽  
Excessive Force ◽  
Molding Machine ◽  
Preliminary Model ◽  
Wide Range

A force-limiting buckling flexure has been created which can be used in a wide range of applications where excessive force from an implement can cause harm or damage. The buckling flexure is monolithic, contains no electronics, and can be manufactured using a single shot in an injection molding machine, making it cost effective. In this paper, the design of the flexure is applied to a force-limiting toothbrush as a design study to show its application in a real-world technology. An overview of the buckling flexure is presented, and a structural model is presented to predict when the flexure will elastically buckle. Flexures of different geometries were tested and buckled. The data show that the model can predict buckling of the flexure with an error of 20.84%. A finite element model was also performed which predicts buckling of the flexure within an error of 25.35%. Furthermore, a preliminary model is presented which enables the design of the buckling beam’s displacement, such that the total breakaway deformation can be maximized, making sensing the sudden deformation easier to detect. As part of the application of the buckling flexure, an ergonomic, injection moldable toothbrush was created with the flexure built into the neck of the brush. When the user applies too much force while brushing, the flexure gives way and alerts the user when they have applied too much force; when the user lets off the force, the brush snaps back to its original shape. This design methodology is generalized and can be utilized in other force limited applications where an injection-moldable, pre-set force, and purely mechanical breakaway device is desired.

A multidisciplinary approach to the engineering of footwear cushioning: A practical example of gym training shoes

2020 ◽  
pp. 175433712095722
Author(s):  
Cédric YM Morio ◽  
Laura Bouten ◽  
Simon Duraffourg ◽  
Nicolas Delattre
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Multidisciplinary Approach ◽  
Wear Test ◽  
Sensory Panel ◽  
Optimal Amount ◽  
Shoe Design ◽  
Wide Range ◽  
The Relationship

According to sports goers, one of the most important features of gym training shoes is their cushioning properties. The optimal amount of cushioning is, however, complex to define. In the present paper, a multi-disciplinary approach was proposed to investigate and determine the optimal perceived midsole cushioning for gym training shoes. Firstly, impact tests were performed to characterise a wide range of shoes representing the gym training shoe market. Trained sensory panel method and mechanical testing were combined to determine the relationship between the perception of cushioning and the shoe’s mechanical properties. Secondly, the preferred cushioning perception was assessed. Then, numerous midsole configurations were tested using finite element method (FEM) to determine the combinations with the best cushioning properties in order to reduce the number of physical prototypes. To assess the best configuration estimated by the numerical model, a wear test was performed as a final validation. From this approach, relationship between the mechanical properties of the midsole and perception of cushioning was found, and an optimal perceived cushioning was identified. Moreover, through FEM numerical simulations, a great number of midsole configurations and designs were tested without making any actual prototypes. Prototype shoes were based on the best numerical solution. The final wear test confirmed that the prototype gym training shoes achieved the preferred perception of cushioning. The present methodology proposes a framework, which empowers the use of athlete’s and exerciser’s perception in shoe design.

Research on PET Beer Bottle Structural Parameters and it’s Strength

2013 ◽  
Vol 641-642 ◽  
pp. 488-491
Author(s):  
Wei Yuan ◽  
Li Hua Xie ◽  
Gai Mei Zhang ◽  
Da Zhi Liao ◽  
Jian Dong Lu
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Internal Pressure ◽  
Structural Parameters ◽  
Analysis Software ◽  
Element Analysis ◽  
Main Factors ◽  
Different Thickness

According to the formula of the resistance to internal pressure, the main factors of the strength of the beer bottles are analyzed. Using ANSYS finite element analysis software, PET beer bottles damaged boundary conditions are determined. PET beer bottle model is established, and have the stress analysis. The internal pressure and the bottle top pressure are applied on PET beer bottles. PET beer bottles strain is analyzed in two loads with different thickness and different bottle diameter. Thickness and bottle diameter influence of the mechanical properties of PET beer bottles are obtained. It provides a method and basis of the structure to optimize the design of PET beer bottles.

The Effects of Operational, Testing and Material Characterisations On the Change in Yield Strength From Plate to Pipe

2021 ◽  
Author(s):  
Jingsi Jiao ◽  
Cheng Lu ◽  
Valerie Linton ◽  
Frank Barbaro
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Yield Strength ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Element Model ◽  
Critical Knowledge ◽  
Operational Testing ◽  
Wide Range ◽  
The Individual

Abstract The mechanical performance of the pipe sample has a direct influence on their application in real environments and a significant economic impact on manufacturers, especially when the pipe products do not meet required specifications. There is often a change in the yield strength from plate to pipe due to strain hardening and the Bauschinger effect. The current work sets out to provide a critical knowledge base for this change, with emphasizing the important influence of the plate mechanical properties on the pipe. So that the quality of pipe can be further ensured. In the work, firstly, the historical data of the pipe yield strength were collected and plotted together from a wide range of published sources to provide a broad quantitative insight, which provides a quantitative review on the parameters that govern the final pipe yield strength. Secondly, a Finite Element model of the pipe forming and mechanical evaluation was developed and then validated with available industrial testing results, in where the effects of operational and testing parameters on the pipe yield strength were analysed and discussed in detail. Finally, using the validated Finite Element model, a parametric study was conducted to dissect the individual role that each of the material parameters plays on changing the yield strength from plate to pipe. We found that the yield strength of the pipe can differ significantly. This work sheds lights on the desired plate mechanical properties to optimize the final pipe yield strength.

Research on the Influence of the Stiffening Plates on the Stress of Hold Hoop of Bent Cap

2019 ◽  
Vol 815 ◽  
pp. 223-228
Author(s):  
Qin Tian ◽  
Cheng Hao Hang ◽  
Yun Peng Zou ◽  
Zi Xin Wan
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Concentration ◽  
Structural Parameters ◽  
Great Influence ◽  
Finite Element Models ◽  
Finite Element Software ◽  
Bridge Steel ◽  
Calculation Results ◽  
Shell Finite Element

In order to improve the mechanical behaviour of bridge steel hoops, the plate shell finite element models of several steel hoops were established by using the general finite element software ABAQUS. Through changing the structural parameters of the stiffening plates, the influence of the stiffening plates on the mechanical properties of the steel hoops was explored. The calculation results show that the stress distribution at both ends of the steel hoop is uneven and there is a phenomenon of stress concentration. The spacing of stiffening plates has great influence on the mechanical properties of steel hoop. Some measures to improve the mechanical properties of steel hoop are given.

Numerical Modelling of Compression Stress Relaxation and Compression Set of Elastomer O-Ring During Aging

2020 ◽  
Author(s):  
Maha Zaghdoudi ◽  
Mike Weber ◽  
Anja Kömmling ◽  
Matthias Jaunich ◽  
Dietmar Wolff
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stress Relaxation ◽  
Radioactive Waste ◽  
Radioactive Material ◽  
High Level Waste ◽  
Compression Stress ◽  
Compression Set ◽  
Wide Range

Abstract Elastomer seals are used in many industrial applications due to their excellent mechanical properties at a wide range of temperatures. Their high versatility and recovery potential under several load conditions make them well suitable for the application in containers designed for transport, storage and/or disposal of radioactive materials. In containers for low and intermediate level radioactive waste, elastomer seals are used as barrier seals, and as auxiliary seals in storage and transportation casks (dual purpose casks) for heat generating radioactive waste, such as spent fuel and high-level waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered and prohibit an unnecessary cask handling. An extensive knowledge of the change of the elastomer’s properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the permanent safe enclosure of the radioactive material is mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have been already made and are still planned to scientifically support this task. Compression stress relaxation and compression set were identified as key indicators of elastomer long-term performance and quantitatively investigated in comprehensive test programs. Among other representative types of elastomers, specimens made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the most important of their complex mechanical properties. In the presented study, exemplary results were used to simulate the compression stress relaxation and the compression set of elastomer O-rings during aging. Regarding the influence of temperature, the time-temperature superposition principle is applied in the relaxation analysis of elastomer O-rings. The proposed model is implemented in the commercial finite element software ABAQUS/Standard® [1] with a sequential temperature displacement coupling. Numerical results match the experimental compression stress relaxation measurements well. The prediction of compression set values after long-term aging shows a relatively good agreement with the experimental results. Nevertheless, all input parameters derived from the specimen tests, additional assumptions concerning boundary conditions and modeling strategy are discussed with regard to the identified slight discrepancies. The possibility to extend the finite element model to represent the O-ring seal’s ability to recover after a (fast) partial release is taken into account.

A finite element model of an idealized diarthrodial joint to investigate the effects of variation in the mechanical properties of the tissues

2003 ◽  
Vol 217 (5) ◽  
pp. 341-348 ◽  
Author(s):  
F H Dar ◽  
R M Aspden
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Articular Cartilage ◽  
Finite Element Model ◽  
Factorial Design ◽  
Subchondral Bone ◽  
Element Model ◽  
Bone Plate ◽  
Subchondral Bone Plate ◽  
Wide Range

The stiffness of articular cartilage increases dramatically with increasing rate of loading, and it has been hypothesized that increasing the stiffness of the subchondral bone may result in damaging stresses being generated in the articular cartilage. Despite the interdependence of these tissues in a joint, little is understood of the effect of such changes in one tissue on stresses generated in another. To investigate this, a parametric finite element model of an idealized joint was developed. The model incorporated layers representing articular cartilage, calcified cartilage, the subchondral bone plate and cancellous bone. Taguchi factorial design techniques, employing a two-level full-factorial and a four-level fractional factorial design, were used to vary the material properties and thicknesses of the layers over the wide range of values found in the literature. The effects on the maximum values of von Mises stress in each of the tissues are reported here. The stiffness of the cartilage was the main factor that determined the stress in the articular cartilage. This, and the thickness of the cartilage, also had the largest effect on the stresses in all the other tissues with the exception of the subchondral bone plate, in which stresses were dominated by its own stiffness. The stiffness of the underlying subchondral bone had no effect on the stresses generated in the cartilage. This study shows how stresses in the various tissues are affected by changes in their mechanical properties and thicknesses. It also demonstrates the benefits of a structured, systematic approach to investigating parameter variation in finite element models.

scholarly journals Modelling the change in structure and mechanical properties in dry-snow densification to ice

1998 ◽  
Vol 26 ◽  
pp. 45-50 ◽  
Author(s):  
Vladimir N. Golubev ◽  
Anatoly D. Frolov
Keyword(s):  
Mechanical Properties ◽  
Porous Media ◽  
Physical Properties ◽  
Coordination Number ◽  
Structural Changes ◽  
Structural Parameters ◽  
Experimental Studies ◽  
Density Increase ◽  
Regular Packing ◽  
Good Agreement

The regular packing of spheres or polyhedrons of various shapes linked by rigid bonds is presented and discussed as a model of snow structure. Basic structural parameters of this model are: the coordination number and introduced dimensionless factors of friability and rigidity. The snow densification is described as successive changes of these parameters. Use of the model allows us to relate the density increase from ~130 to ~320, ~550, ~700, ~820 and 917 kg m−3, while the coordination number of the structure increases accordingly from 3 (friable hexagonal) to 4 (tetrahedral), 6 (cubic), 8, 10, 12 (dense hexagonal). These structural changes are in good agreement with the critical densities established in experimental studies of snow densification and the physical properties of snow. It is shown that the model presented allows us to estimate the mechanical properties of ice-porous media: Young’s modulus, Poisson’s ratio and strength.

scholarly journals Thermal Prestress in Composite Compliant Shell Mechanisms

2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Jonathan P. Stacey ◽  
Matthew P. O'Donnell ◽  
Mark Schenk
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Finite Element ◽  
Composite Laminate ◽  
Compliant Mechanisms ◽  
Low Energy ◽  
Spring Model ◽  
Energy Landscapes ◽  
Thermally Induced ◽  
Good Agreement

This paper explores the ability to tailor the mechanical properties of composite compliant shell mechanisms, by exploiting the thermal prestress introduced during the composite laminate cure. An extension of an analytical tape spring model with composite thermal analysis is presented, and the effect of the thermal prestress is studied by means of energy landscapes for the cylindrical composite shells. Tape springs that would otherwise be monostable structures become bistable and exhibit greater ranges of low-energy twisting with thermally induced prestress. Predicted shell geometries are compared with finite element (FE) results and manufactured samples, showing good agreement between all approaches. Wider challenges around the manufacture of prestressed composite compliant mechanisms are discussed.

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