Behavior of Indented Sandwiches Structure with Nomex Honeycomb Core and Metallic Skins Subjected to Compressive Loading (CAI)

2007 ◽  
Vol 345-346 ◽  
pp. 729-732
Author(s):  
Y. Aminanda ◽  
B. Castanie ◽  
J.J. Barrau
Keyword(s):  
Residual Strength ◽  
Compressive Loading ◽  
Element Model ◽  
Honeycomb Core ◽  
Uniform Compression ◽  
Compression Load ◽  
Damage Area ◽  
Result Show ◽  
Nomex Honeycomb ◽  
Test Result

A finite element model is proposed to determine the residual strength and the evolution of damage area of indented sandwiches structures with Nomex honeycomb core and metallic skins indented by a spherical indenter under longitudinal compression load (CAI). The honeycomb is represented by a grid of non-linear springs which its behavior law is obtained by performing simple transverse uniform compression test on a block of honeycomb alone.The comparisons between computation and test result show that the model can simulate accurately the form of damage geometry during indentation, its residual print when the load is relieved (relaxation) and the residual strength and the evolution of damage geometry during CAI.

Numerical Analysis and Mechanical Properties of Nomex™ Honeycomb Core

2017 ◽  
Author(s):  
Yue Liu ◽  
Weicheng Gao ◽  
Wei Liu ◽  
Zhou Hua
Keyword(s):  
Compressive Strength ◽  
Cell Walls ◽  
Mechanical Response ◽  
Compressive Loading ◽  
Fe Model ◽  
Honeycomb Core ◽  
Practical Applications ◽  
Honeycomb Sandwich ◽  
Nomex Honeycomb ◽  
Strength And Stiffness

This paper presents an investigation on the mechanical response of the Nomex honeycomb core subjected to flatwise compressive loading. Thin plate elastic in-plane compressive buckling theory is used to analyze the Nomex honeycomb core cell wall. A mesoscopic finite element (FE) model of honeycomb sandwich structure with the Nomex honeycomb cell walls is established by employing ABAQUS/Explicit shell elements. The compressive strength and compressive stiffness of Nomex honeycomb core with different heights and thickness of cell walls, i.e. double cell walls and single cell walls, are analyzed numerically using the FE model. Flatwise compressive tests are also carried out on bare honeycomb cores to validate the numerical method. The results suggest that the compressive strength and compression stiffness are related to the geometric dimensions of the honeycomb core. The Nomex honeycomb core with a height of 6 mm has a higher strength than that of 8 mm. In addition, the honeycomb core with lower height possesses stronger anti-instability ability, including the compressive strength and stiffness. The proposed mesoscopic model can effectively simulate the crushing process of Nomex honeycomb core and accurately predict the strength and stiffness of honeycomb sandwich panels. Our work is instructive to the practical applications in engineering.

Residual Strength and Failure Criterion of PP Thermoplastic Honeycomb Sandwich Subjected to Low Velocity Impact

2011 ◽  
Vol 471-472 ◽  
pp. 646-651 ◽  
Author(s):  
A. Freeda Amir ◽  
A.R. Othman
Keyword(s):  
Impact Energy ◽  
Residual Strength ◽  
Failure Modes ◽  
Structural Integrity ◽  
Peak Load ◽  
Low Velocity Impact ◽  
Honeycomb Core ◽  
Low Velocity ◽  
Velocity Impact ◽  
Damage Area

This paper presented the effect of constituent materials on impact damage and strength reduction of sandwich structure, composed of laminated woven E-glass facesheets and polypropylene thermoplastic honeycomb core. Effect of low-velocity impact was the main interest in a variety of layered configurations. Compression after impact (CAI) has been carried out to determine the residual strength of impacted sandwich structures. Three different thicknesses of core of 20, 40 and 60mm subjected to three different levels of impact energy of 15, 30 and 45J were investigated. Impact response of the panel was recorded and analyzed in terms of peak load, indentation, energy absorbed and time. A profile analysis using optical 3D surfaces profiler was carried out to attain the indentation depth and damage area of the samples. The tested samples were then sectioned into halves to capture the failure mode or damaged sequence of the polypropylene thermoplastic honeycomb core. The dominant failure modes of the core indicated that polypropylene thermoplastic honeycomb core is a high strength material which can absorb higher impact energy and retain a higher degree of structural integrity.

Modelling damage evolution and CAI strength of composite laminates under biaxial compression

2021 ◽  
pp. 002199832199842
Author(s):  
Bin Yang ◽  
Kunkun Fu ◽  
Yan Li
Keyword(s):  
Residual Strength ◽  
Composite Laminates ◽  
Failure Modes ◽  
Compressive Loading ◽  
Element Model ◽  
Low Velocity Impact ◽  
Biaxial Compression ◽  
Low Velocity ◽  
Damage Initiation ◽  
Compression After Impact

In this paper, a finite element model (FEM) was developed to investigate failure mechanism and compression after impact (CAI) strength of woven carbon fibre reinforced polymer (CFRP) after low-velocity impact (LVI) subjected to biaxial compressive loading. A built-in VUMAT user-defined material subroutine was adopted to take into account the in-plane damage and intralaminar delamination under LVI loading and in-plane compression. The LVI response, failure pattern, and residual mechanical properties under uniaxial compression were compared to the available experimental data to verify the numerical model. The damage initiation, subsequent evolution, final failure modes, and residual strength of the composite laminates with LVI damages subjected to biaxial compressive loading are presented by numerical methods, and the effects of impact energy and impactor diameter on the residual strength of the laminates are discussed.

scholarly journals Hygrothermal Ageing Influence on BVI-Damaged Carbon/Epoxy Coupons under Compression Load

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2038
Author(s):  
Maria Pia Falaschetti ◽  
Matteo Scafé ◽  
Nicola Zavatta ◽  
Enrico Troiani
Keyword(s):  
Residual Strength ◽  
Impact Damage ◽  
Mechanical Analysis ◽  
Test Method ◽  
Combined Loading ◽  
Compression Load ◽  
Impact Location ◽  
Hygrothermal Ageing ◽  
Influence Of Water ◽  
Compressive Tests

Composite materials usage in several industrial fields is now widespread, and this leads to the necessity of overcoming issues that are still currently open. In the aeronautic industry, this is especially true for Barely Visible Impact Damage (BVID) and humidity uptake issues. BVID is the most insidious kind of impact damage, being rather common and not easily detectable. These, along with the ageing that a composite structure could face during its operative life, could be a cause of fatal failures. In this paper, the influence of water absorption on impacted specimens compressive residual strength was studied. Specimens were impacted using a modified Charpy pendulum. Two different locations were chosen for comparison: Near-Edge (NE) and Central (CI). Accelerated hygrothermal ageing was conducted on impacted and reference nonimpacted coupons, placing them in a water-filled jar at 70 °C. Compressive tests were performed in accordance with the Combined Loading Compression (CLC) test method. A Dynamic Mechanical Analysis (DMA) was performed as well. The results showed the influence of hygrothermal ageing, as expected. Nevertheless, the influence of impact location on compressive residual strength is not clearly noticeable in aged specimens, leading to the conclusion that hygrothermal ageing may have a greater effect on composite compressive strength than the analysed BVI damage.

scholarly journals Mechanical Behavior of a Calcium Phosphate Ceramic Bone Graft Used in the Rehabilitation of a C4 Human Vertebra

2007 ◽  
Vol 7-8 ◽  
pp. 101-106 ◽  
Author(s):  
Juan Alfonso Beltrán-Fernández ◽  
Luis Héctor Hernández-Gómez ◽  
R.G. Rodríguez-Cañizo ◽  
G. Urriolagoitia-Calderón ◽  
G. Urriolagoitia-Sosa ◽  
...  
Keyword(s):  
Bone Graft ◽  
Experimental Tests ◽  
Element Model ◽  
Calcium Phosphate Ceramic ◽  
Compression Load ◽  
Head Weight ◽  
Anterior Side ◽  
Average Patient ◽  
On Line ◽  
Cervical Plate

The main results of a static analysis with a finite element model of the cervical section between C3 – C5 of a human spine are reported. In this case, it is assumed that the element C4 is completely damaged and has to be replaced. Therefore, a bone graft was installed between the anterior side of C3 and C5. Besides, a cervical plate of 55 mm. was fixed at the same side with 4 expansive screws. The resultant stresses caused by compression loads were analyzed and the displacements between the graft and adjacent vertebrae were calculated. Three loading conditions were applied: 80 N, 637.5 N and 6374.5 N. The first one corresponds to the head weight. In the second case, it is assumed that the average patient weight is supported by those vertebrae, while in the last one; the compression load failure is applied on the vertebrae. Results show that displacements were lower than 3 mm between the graft and the adjacent vertebrae. In accordance with the concept of spine stability after Müller [1], the arrangement is a stable one. Another advantage is that no wires are used in this surgical technique. Two more issues should be noticed. There is no risk that the plate may be broken and the geometry of the bone graft allows bone regeneration. These results are on line with those observed in preliminary experimental tests with porcine vertebrae.

scholarly journals Pre-drilling and self-drilling pins screw-bone fixation stress interaction analysis induced by uniaxial compression loading

2019 ◽  
Vol 15 (1) ◽  
pp. 99-108
Author(s):  
Lim Pei Chee ◽  
Ruslizam Daud ◽  
Shah Fenner Khan Mohamad Khan ◽  
Nurul Alia Md Zain ◽  
Yazid Bajuri
Keyword(s):  
Uniaxial Compression ◽  
External Fixator ◽  
Bone Fractures ◽  
Interaction Analysis ◽  
Compressive Loading ◽  
Three Dimensional ◽  
Maximum Magnitude ◽  
Element Analysis ◽  
Compression Load ◽  
Von Mises

A newly designed Uniaxial external fixator which functions as a universal fixator in the application of all types of bone fractures is recently introduced by both Hospital Universiti Kebangsaan Malaysia (HUKM) and Universiti Malaysia Perlis (UniMAP). The Investigation is focused on identifying and measuring the performance in terms of strength or weakness of the fixator that is needed before the application to the human body. Hence, this research was conducted to determine the performance of Uniaxial external fixator which was based on geometry using different screw drilling techniques applied during an angled uniaxial compression load.  A three-dimensional fixator-bone was constructed using different screw inserting techniques which was then converted into ANSYS v14.5 for the purposes of conducting a finite element analysis (FEA).  Axial compressive loading with various degrees from 60 to 6300 N were applied to bone models to stimulate patient’s daily activities while 10 to 100 N were applied to fixator models for the purposes of reviewing environmental loading to fixator-bone models. Findings revealed that maximum magnitude which caused deformation for predrilling and self-drilling models were located at the highest pin-bone interaction. Conversely, the maximum magnitude of the von Mises strain and stress was located at the lowest pin-bone interaction by omitting the existence of fixator for both Case 1 and 2. There was no obvious difference in the comparison of both models in terms of deformation. However, predrilling models have higher strain and stress than self-drilling models. In sum, findings indicated that self-drilling models have better performance compared to the predrilling models.

scholarly journals The Psychological Well-Being among Government and Non Government School Teachers: A Comparative Study

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Kiran Vaghela
Keyword(s):  
Data Collection ◽  
Comparative Study ◽  
Well Being ◽  
School Teachers ◽  
Government School ◽  
Psychological Well Being ◽  
Male And Female ◽  
Significant Difference ◽  
Result Show ◽  
Test Result

Aim of the research is to find out the Psychological Well-being among School teachers. So investigator selected two groups one is government school teachers  and other is  non government school teachers, both groups have 400 persons. In one group has 200 and other one groups has 200 persons. The all subjects were randomly selected. Data were collected from Ahmadabad district. Scale was use for data collection is personal datasheet and Psychological Well-being scale developed by Bhogale and Prakash (1995), and data were analysis by “f” test. Result show, There is no significant difference between the psychological well-being of government and non government school teachers. There is no significant difference between the psychological well-being of male and female and urban and rural area.

scholarly journals Psychological Adjustment: A Comparative Study of the Joint and Nuclear Families People Willing To Take Divorce

2014 ◽  
Vol 1 (2) ◽  
Author(s):  
Sunil S. Jadav
Keyword(s):  
Data Collection ◽  
Comparative Study ◽  
Psychological Adjustment ◽  
T Test ◽  
Mean Difference ◽  
Nuclear Families ◽  
Result Show ◽  
High Age ◽  
Test Result

Aim of the research is to find out the Psychological adjustment among joint and nuclear families people willing to take divorce, both groups have 160 peoples. In one group has 90 joint and another group has 70 nuclear families people. The all subjects were simple randomly selected. Data were collected from Anand district. Scale was use for data collection is personal datasheet and Psychological adjustment Scale was developed by Bell (1905) and Gujarati-translated by Bhatt, (1994) was used. Data were analysis by ‘t’ test. Result show, There is no significant mean difference of psychological adjustment between joint and nuclear families people. There is no significant mean difference of the Psychological adjustment between low and high age people. There is no significant mean difference of the Psychological adjustment between low, medium and high total monthly incomes people.

scholarly journals Work Value among Married and Unmarried Person’: A Comparative Study

2014 ◽  
Vol 1 (2) ◽  
Author(s):  
Ramesh O. Prajapati
Keyword(s):  
Data Collection ◽  
Comparative Study ◽  
T Test ◽  
Nuclear Families ◽  
Significant Difference ◽  
Low Incomes ◽  
Result Show ◽  
Work Value ◽  
Test Result ◽  
Better Than

Aim of the research is to find out the Work value among married and unmarried person’s. So investigator selected two groups one is married and other is unmarried persons, both groups have 200 persons. In one group has 113 married and other one groups has 87 unmarried persons. The all subjects were randomly selected. Data were collected from Ahmadabad district. Scale was use for data collection is personal datasheet and Work value scale developed by super (1970) and this scale was translated into Gujarati by Jalawadiya (2002), and data were analysis by ‘t’ test. Result show, There is no significant mean difference of Work value between married and unmarried persons. There is no significant difference of the Work value of joint and nuclear families. The high income persons work value is better than the low incomes.

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