Über die mechanische Bedeutung der Holzstrahlen | The mechanical relevance of wood rays

2003 ◽  
Vol 154 (12) ◽  
pp. 498-503 ◽  
Author(s):  
Ingo Burgert
Keyword(s):  
Beech Wood ◽  
Tensile Tests ◽  
Deciduous Tree ◽  
Biological Design ◽  
Transverse Tensile ◽  
Radial Reinforcement ◽  
Radial Strength ◽  
Transverse Tensile Strength ◽  
Strength And Stiffness ◽  
Technical Solutions

Three investigations into the mechanical relevance of wood rays were combined for this article. The main objective was to show, that, apart from physiological functions, rays also significantly influence the radial strength and stiffness of wood. In the first approach twelve deciduous tree species with various proportions of fractions of rays were examined for their transverse tensile strength and stiffness. The second approach was based on the comparison of the radial mechanical properties of wood with a very high proportion of fraction of rays and beech wood with a normal volume. In these two investigations the mechanical relevance of rays could only be deduced indirectly. By isolating big rays of beech and carrying out tensile tests on the tissue, we found direct evidence for the mechanical relevance. The results are discussed with regard to their biomechanical relevance. The importance of a radial reinforcement for the wood is underlined. Moreover, the principle of multi-functionality in nature is emphasized in keeping with a possible transfer of biological design to technical solutions.

Progressive damage characteristics of screwed single-lap CFRPI-metal joint subjected to tensile loading at RT and 350°C

2021 ◽  
pp. 002199832098559
Author(s):  
Yun-Tao Zhu ◽  
Jun-Jiang Xiong ◽  
Chu-Yang Luo ◽  
Yi-Sen Du
Keyword(s):  
Damage Model ◽  
Tensile Loading ◽  
Tensile Tests ◽  
Displacement Curve ◽  
Progressive Damage ◽  
Damage Characteristics ◽  
Metal Joint ◽  
Static Tensile ◽  
Strength And Stiffness ◽  
Progressive Damage Model

This paper outlines progressive damage characteristics of screwed single-lap CFRPI-metal joints subjected to tensile loading at RT (room temperature) and 350°C. Quasi-static tensile tests were performed on screwed single-lap CCF300/AC721-30CrMnSiA joint at RT and 350°C, and the load versus displacement curve, strength and stiffness of joint were gauged and discussed. With due consideration of thermal-mechanical interaction and complex failure mechanism, a modified progressive damage model (PDM) based on the mixed failure criterion was devised to simulate progressive damage characteristics of screwed single-lap CCF300/AC721-30CrMnSiA joint, and simulations correlate well with experiments. By using the PDM, the effects of geometry dimensions on mechanical characteristics of screwed single-lap CCF300/AC721-30CrMnSiA joint were analyzed and discussed.

scholarly journals Parametric study on the behaviour of bagasse ash-calcium carbide residue stabilized soil

2018 ◽  
Vol 195 ◽  
pp. 03015
Author(s):  
John Tri Hatmoko ◽  
Hendra Suryadharma
Keyword(s):  
Calcium Carbide ◽  
Friction Angle ◽  
Tensile Tests ◽  
Peak Strength ◽  
Compression Tests ◽  
Exchange Reactions ◽  
Short Term ◽  
Calcium Carbide Residue ◽  
Stabilized Soil ◽  
Strength And Stiffness

A series of experiments including unconfined compression tests, three-axial tests, compaction tests, and split tensile tests were undertaken to investigate the influence of compaction parameters on the behaviour of bagasse ash-calcium carbide residue stabilized soil. A preliminary study on soil with the addition of 4%, 6%, 8%, 10%, and 12% calcium carbide residue established that the lime fixation point (LFP) was 4%. Then 9% bagasse ash was added to soil with 4% calcium carbide residue, and the cation exchanges and pozzolanic reactions were investigated. The addition of calcium carbide residue to bagasse ash stabilized soil caused short-term changes due to cation exchange reactions, including an increase in the friction angle and cohesion in the stabilized soil. In addition, due to the short-term reaction, the maximum stiffness in three-axial tests occurred in the samples moulded with less than their optimum moisture content (OMC), whereas the peak strength occurred in the samples moulded at their OMC. After a 28-day curing period, pozzolanic reactions improved significantly the three-axial peak strength and stiffness of the stabilized soil, and the maximum three-axial shear strength and stiffness occurred in the samples prepared below their OMC.

Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated temperature

2019 ◽  
Vol 54 (13) ◽  
pp. 1705-1715
Author(s):  
MHR Jen ◽  
GT Kuo ◽  
YH Wu ◽  
YJ Chen
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Composite Laminates ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Constant Length ◽  
Nano Powder ◽  
Strength And Stiffness ◽  
Inclined Angle

The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.

Estimation of transverse tensile behavior of Zircaloy pressure tubes using ring-tensile test and finite element analysis

2012 ◽  
Vol 227 (6) ◽  
pp. 1177-1186 ◽  
Author(s):  
MK Samal ◽  
KS Balakrishnan ◽  
J Parashar ◽  
GP Tiwari ◽  
S Anantharaman
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Tensile Tests ◽  
Tensile Specimen ◽  
Displacement Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
Transverse Tensile ◽  
Pressure Tubes ◽  
Load Displacement

Determination of transverse mechanical properties from the ring type of specimens directly machined from the nuclear reactor pressure tubes is not straightforward. It is due to the presence of combined membrane as well as bending stresses arising in the loaded condition because of the curvature of the specimen. These tubes are manufactured through a complicated process of pilgering and heat treatment and hence, the transverse properties need to be determined in the as-manufactured condition. It may not also be possible to machine small miniaturized specimen in the circumferential direction especially in the irradiated condition. In this work, we have performed ring-tensile tests on the un-irradiated ring tensile specimen using two split semi-cylindrical mandrels as the loading device. A three-dimensional finite element analysis was performed in order to determine the material true stress–strain curve by comparing experimental load–displacement data with those predicted by finite element analysis. In order to validate the methodology, miniaturized tensile specimens were machined from these tubes and tested. It was observed that the stress–strain data as obtained from ring tensile specimen could describe the load–displacement curve of the miniaturized flat tensile specimen very well. However, it was noted that the engineering stress–strain as directly obtained from the experimental load–displacement curves of the ring tensile tests were very different from that of the miniaturized specimen. This important aspect has been resolved in this work through the use of an innovative type of 3-piece loading mandrel.

Experimental reexamination of transverse tensile strength for IM7/8552 tape-laminate composites

2020 ◽  
Vol 54 (23) ◽  
pp. 3297-3312
Author(s):  
Caitlin M Arndt ◽  
Nelson V de Carvalho ◽  
Michael W Czabaj
Keyword(s):  
Tensile Strength ◽  
Weak Link ◽  
Surface Preparation ◽  
Test Method ◽  
Transverse Fracture ◽  
Laminate Composites ◽  
Transverse Tensile ◽  
Specimen Volume ◽  
Transverse Tensile Strength

Due to the observed dependence of transverse-tensile strength, Y T, on test geometry and specimen size, there is no consensus regarding a test method that can uniquely measure Y T. This study reexamines the characterization of Y T by comparing results from established flexure tests with results from a new tensile test that exhibits consistent failure in the gage region. Additionally, the effects of surface preparation and direction of transverse fracture are investigated. Results show that Y T is inversely proportional to specimen volume and surface roughness and is insensitive to direction of transverse fracture. The relationship between specimen volume and Y T is adequately captured by Weibull strength-scaling theory, except at the tails of the Y T distributions. However, specimens exhibited microcracking prior to failure, which violates the “weak-link” assumption of the Weibull theory. These findings highlight the challenges of using deterministic Y T values in progressive damage analysis.

scholarly journals Investigation of Interlaminar Defects and their Influence on Interlaminar Strength

1996 ◽  
Vol 5 (4) ◽  
pp. 096369359600500
Author(s):  
J Ziao ◽  
J Tao
Keyword(s):  
Tensile Strength ◽  
Large Scale ◽  
Peel Strength ◽  
Test Method ◽  
Bending Test ◽  
Four Point Bending ◽  
Transverse Tensile ◽  
Interlaminar Shear ◽  
Transverse Tensile Strength ◽  
Set Up

In this paper, we directed our attention to the interlaminar defects and their influence on the interlaminar strengths. With the aid of a S-570 scanning electron microscope, the morphology and distribution of interlaminar defects were inspected and documented. According to their shape, size and cause of formation, the defects were classified into five types: flakiness void, irregular shaped debond, local imperfectly cured resin, debond in two multi-directional plies, and inhomogeneous fibers and the large scale debond by these fibers. The cause of defects formation was discussed by analyzing the manufacturing process of composites. The influence of defects on the interlaminar strength and its mechanism was analyzed experimentally and theoretically. The results indicate that these defects, with different effects, decrease the interlaminar strength because they form interlaminar cracks, and the interlaminar shear strength is less affected than interlaminar tensile strength, which is measured according to GB4944 test method. To comprehend defects distribution effect, a four-point-bending test method was introduced to measure the interlaminar peel strength, and a discussion was made on the correlation between the interlaminar tensile strength, interlaminar peel strength and in-plane transverse tensile strength. Finally the concept of interlaminar defect coefficient, which can be used to characterize the defects, was set up and the formula to calculate it was proposed.

Influence of Heat Treatment on Properties of 2219AA-T6 FSW Joints

2014 ◽  
Vol 590 ◽  
pp. 187-191 ◽  
Author(s):  
Chuan Hong Luo ◽  
Wei Ping Peng ◽  
Ting Chen ◽  
Fei Bo Dong
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Friction Stir Welding ◽  
Joint Strength ◽  
Alloy Plate ◽  
Friction Stir ◽  
Transverse Tensile ◽  
Aluminum Alloy Plate ◽  
Transverse Tensile Strength ◽  
Short Time

The joint of 2219-T6 aluminum alloy plate was obtained by friction stir welding, and the microstructures and mechanical properties of the joint were investigated. The causes of the weakened joint strength in friction stir welding were analyzed and summarized correspondingly. The tensile properties show that the transverse tensile strength of the joint can reach about 70% of the base metal. Through the heat treatment of recrystallization with high temperature and at short time, the joint can restore the ductility and eliminate the softening, which will improve the performance in mechanical intensity of the joint.

Dissimilar Friction Stir Welding of 2014 to 6061 Aluminum Alloys

2011 ◽  
Vol 409 ◽  
pp. 269-274 ◽  
Author(s):  
Caroline Jonckheere ◽  
Bruno de Meester ◽  
Anne Denquin ◽  
Aude Simar
Keyword(s):  
Metal Flow ◽  
High Strength ◽  
Tensile Tests ◽  
Al Alloys ◽  
Weld Nugget ◽  
Welding Parameters ◽  
Friction Stir ◽  
Initial Separation ◽  
Transverse Tensile ◽  
Dissimilar Welds

Welding cheap and ductile 6xxx Al alloys with high strength 2xxx Al alloys is desirable for instance in specific aeronautical applications. These alloys present different rheological behaviors and melting temperatures which affect the ability to produce sound dissimilar friction stir welds. Dissimilar friction stir butt welds made of 2014-T6 and 6061-T6 Al alloys were performed with various welding parameters including shifts of the tool from the initial separation between the plates to be welded and placing one alloy either on the advancing, or on the retreating side of the weld. Temperature measurements during welding, mechanical characterization (transverse tensile tests and hardness profiles) and macrographic observations were performed. Macrographies on sections perpendicular to the welding direction reveal different metal flow patterns in the weld nugget. If the 2014 alloy is placed on the advancing side of the weld, an abrupt transition between the weld nugget and the 6061 alloy is observed on macrographs leading to premature fracture in tension. Dissimilar welds are cooler on the 6061 side of the weld, i.e. the weakest side of the weld, than the corresponding 6061 similar weld, limiting the growth of the hardening precipitates. This leads thus to higher strength of the dissimilar welds. Dissimilar welds with the weld center shifted towards the 2014 alloy present lower temperatures than unshifted welds on the 6061 side of the weld, also leading to higher strength.

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