scholarly journals On the infinitely-stable rotational mechanism using the off-axis rotation of a bistable translational mechanism

2015 ◽  
Vol 6 (1) ◽  
pp. 75-80 ◽  
Author(s):  
G. Hao ◽  
J. Mullins
Keyword(s):  
Nonlinear Finite Element ◽  
Critical Transition ◽  
Element Analysis ◽  
Primary Motion ◽  
Prior Art ◽  
Transition Points ◽  
Axis Rotation ◽  
Translational Mechanisms ◽  
Rotation Behaviour

Abstract. Different from the prior art concentrating on the primary translation of bistable translational mechanisms this paper investigates the off-axis rotation behaviour of a bistable translational mechanism through displacing the guided primary translation at different positions. Moment-rotation curves obtained using the nonlinear finite element analysis (FEA) for a case study show the multiple stable positions of the rotation under each specific primary motion, suggesting that an infinitely-stable rotational mechanism can be achieved by controlling the primary motion. In addition, several critical transition points have been identified and qualitative testing has been conducted for the case study.

A Technique to Characterize Rate-Dependent Failure Envelopes in Surface Mount Assemblies

2006 ◽  
Author(s):  
J. Varghese ◽  
A. Dasgupta
Keyword(s):  
Finite Element Analysis ◽  
Failure Strain ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Rate Dependent ◽  
Strain And Strain Rate ◽  
Failure Envelopes ◽  
Dependent Failure ◽  
Printed Wiring Assemblies

This paper characterizes the fatigue failure envelopes for solder damage in Printed Wiring Assemblies (PWAs) subjected to dynamic loading. An empirical, rate-dependent, power-law durability model, motivated by mechanistic considerations, is used to characterize the failure envelopes in terms of PWA flexural strain and strain rate. Explicit nonlinear finite element analysis (FEA) is used to make the damage constants independent of the specimen geometry and characterize the durability in terms of the ratio of solder plastic strain to its failure strain. A case study, using a simple PWA specimen containing a single area array component, is presented to demonstrate the proposed approach.

Extended Nonlinear Analysis of Exactly-Constrained Compliant Compound Parallelogram Mechanisms

2015 ◽  
Author(s):  
Guangbo Hao ◽  
Haiyang Li ◽  
George Joseph
Keyword(s):  
Nonlinear Analysis ◽  
Axial Force ◽  
Thermal Effects ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Motion Direction ◽  
Modal Frequency ◽  
Primary Motion ◽  
Axial Forces ◽  
Forced Excitation

Extended nonlinear analysis of compliant compound parallelogram mechanisms is conducted in this paper. The analytical nonlinear model of a compound basic parallelogram mechanism (CBPM) is first derived incorporating the initial internal axial force. The stiffness equations of compound multi-beam parallelogram mechanisms (CMPMs) are then followed. The effect of initial internal axial forces on the primary motion is further analyzed, which can be employed to consider active displacement preloading control and thermal effects etc. It is shown that negative initial internal axial force will reduce the primary stiffness, and vice versa. The criteria for which the primary stiffness may be considered “constant” is defined and the initial internal axial force driven by temperature change is also formulated. The dynamic analysis of a CMPM using nonlinear finite element analysis (FEA) is finally carried out to show the modal frequency and the forced excitation response in the primary motion direction.

Nonlinear Variation Analysis of Compliant Sheet Metal Assemblies Including Effect of Surface Continuity in Components

2014 ◽  
Vol 532 ◽  
pp. 503-509 ◽  
Author(s):  
Seyed Ali Hashemian ◽  
Behnam Moetakef Imani
Keyword(s):  
Sheet Metal ◽  
Free Probability ◽  
Nonlinear Finite Element ◽  
Variation Analysis ◽  
Element Analysis ◽  
Nonlinear Variation ◽  
Final Assembly ◽  
Highly Nonlinear ◽  
Effect Of Surface

Assembly processes are often complex and highly nonlinear. In sheet metal assemblies, the most important factor that makes the process nonlinear is the contact interaction between mating parts during the assembly process. This paper focuses on developing a methodology for nonlinear variation analysis of compliant sheet metal assemblies which also includes the effect of surface continuity of components. The proposed methodology integrates a nonlinear finite element analysis with an improved sensitivity-free probability analysis in order to predict the final assembly variation. The efficiency of the developed approach is evaluated by an experimental case study as well as Monte Carlo simulation.

A Case Study of the Influence on Crashworthiness From the Implementation of Ice Strengthening

2014 ◽  
Author(s):  
Halvor Larsson Aga ◽  
Bernt Johan Leira ◽  
Sören Ehlers ◽  
Hans Arne Blomvågnes-Bakke
Keyword(s):  
Minimum Distance ◽  
State Of The Art ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Outer Skin ◽  
Collision Safety ◽  
Fuel Tanks ◽  
Ship Collision ◽  
Lng Fuel

This paper presents a study of the influence from ice strengthening on the crashworthiness with regards to placement of LNG fuel tanks. First a brief introduction to the ship collision research as well as an assessment of the state of the art regarding nonlinear finite element analysis for use in ship collision analysis are given. Secondly the implications from the introduction of LNG fuel tanks on ships in context of collision safety are discussed. Thirdly how to quantify and compare energy absorption for different ship designs is discussed. This is followed by the presentation of a study regarding the horizontal placement of LNG fuel tanks. The study starts with presenting the variables chosen and the models made for the analysis. Energy versus indentation curves are presented for three different designs, where a standard cargo carrier is compared with two different design solutions where the cargo carrier is equipped with either vertical or longitudinal ice strengthening. It is concluded that in this case the benefit in terms of reduction of the minimum distance from the outer skin to the LNG fuel tank, as given in the current rules, is around 39%.

scholarly journals Behavior of Offshore Pile in Calcareous Sand—Case Study

2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Tarek N. Salem ◽  
Nadia M. Elkhawas ◽  
Ahmed M. Elnady
Keyword(s):  
Load Capacity ◽  
High Stress ◽  
Embedment Depth ◽  
Shear Stresses ◽  
Northern Coast ◽  
Compression Tests ◽  
Calcareous Sand ◽  
Element Analysis ◽  
Mixing Ratios

The erosion of limestone and calcarenite ridges that existed parallel to the Mediterranean shoreline forms the calcareous sand (CS) formation at the surface layer of Egypt's northern coast. The CS is often combined with broken shells which are considered geotechnically problematic due to their possible crushability and relatively high compressibility. In this research, CS samples collected from a site along the northern coast of Egypt are studied to better understand its behavior under normal and shear stresses. Reconstituted CS specimens with different ratios of broken shells (BS) are also investigated to study the effect of BS ratios on the soil mixture strength behavior. The strength is evaluated using laboratory direct-shear and one-dimensional compression tests (oedometer test). The CS specimens are not exposed to significant crushability even under relatively high-stress levels. In addition, a 3D finite element analysis (FEA) is presented in this paper to study the degradation offshore pile capacity in CS having different percentages of BS. The stress–strain results using oedometer tests are compared with a numerical model, and it gave identical matching for most cases. The effects of pile diameter and embedment depth parameters are then studied for the case study on the northern coast. Three different mixing ratios of CS and BS have been used, CS + 10% BS, CS + 30% BS, and CS + 50% BS, which resulted in a decrease of the ultimate vertical compression pile load capacity by 8.8%, 15%, and 16%, respectively.

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