Interrelationship between the severity of heat treatments and sieve fractions after impact ball milling: a mechanical test for quality control of thermally modified wood

Holzforschung ◽  
2006 ◽  
Vol 60 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Andreas Otto Rapp ◽  
Christian Brischke ◽  
Christian Robert Welzbacher
Keyword(s):  
Mechanical Test ◽  
Robinia Pseudoacacia ◽  
Abies Alba ◽  
Dynamic Strength ◽  
High Energy ◽  
Strength Properties ◽  
Test Method ◽  
Specimen Preparation ◽  
Impact Milling ◽  
Steel Balls

Abstract Thermal modification processes improve the durability and dimensional stability of wood, but strength properties, especially dynamic ones, are compromised. Results from standard dynamic strength testing, such as impact bending tests, suffer from high variability and therefore require a high number of replicates. To overcome this, a new test method named high-energy multiple impact (HEMI) was developed by investigating heat-treated Picea abies Karst., Abies alba Mill. and untreated Robinia pseudoacacia L. The method is based on crushing small specimens by thousands of impacts from pounding steel balls in a heavy vibratory mill. The level of destruction was determined by sieving and analyzing the size distribution of the fragments. We calculated the resistance to impact milling (RIM) based on the mass of the size fractions. RIM shows a linear correlation with the intensity of the thermal treatment. The HEMI test method has the following advantages: small number of specimens, short time for specimen preparation, small variances, and high reproducibility of results.

Detection of fungal decay by high-energy multiple impact (HEMI) testing

Holzforschung ◽  
2006 ◽  
Vol 60 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Christian Brischke ◽  
Christian Robert Welzbacher ◽  
Andreas Otto Rapp
Keyword(s):  
Structural Changes ◽  
Brown Rot ◽  
High Energy ◽  
White Rot ◽  
Fungal Decay ◽  
Highly Correlated ◽  
Thermally Modified Wood ◽  
Impact Milling ◽  
Multiple Impact ◽  
Steel Balls

Abstract The suitability of a previously described high-energy multiple impact (HEMI) test for the detection of early fungal decay was examined. The HEMI test characterises the treatment severity of thermally modified wood by stressing the treated material by thousands of impacts of pounding steel balls. This method differentiates between heat treatment intensities, which are manifest as structural changes in the wood. Similar changes in wood structure are known for wood decayed by fungi. Pine (Pinus sylvestris L.) decayed by brown rot and beech (Fagus sylvatica L.) decayed by white rot were tested. Mass loss caused by fungal decay and resistance to impact milling (RIM) determined in HEMI tests were found to be highly correlated. Testing of non-degraded pine, beech, and ash (Fraxinus exelsior L.) showed only marginal effects of wood density on RIM. Furthermore, annual ring angles and RIM of spruce (Picea abies Karst.) were not correlated. Accordingly, the detection of RIM reduction in decayed wood is not masked by variations in density and orientation of the annual rings. Previous results showed no adverse effects of weathering on RIM. Thus, the detection of fungal decay with HEMI tests is feasible not only for laboratory purposes, but also for wood in outdoor applications that has already undergone weathering.

scholarly journals Evaluation of Energy Absorption Capabilities of Polyethylene Foam under Impact Deformation

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3613
Author(s):  
Baohui Yang ◽  
Yangjie Zuo ◽  
Zhengping Chang
Keyword(s):  
Energy Absorption ◽  
Failure Modes ◽  
High Strain ◽  
Early Stage ◽  
High Energy ◽  
Test Method ◽  
Test Theory ◽  
Strain Rates ◽  
Impact Properties ◽  
The Impact

Foams are widely used in protective applications requiring high energy absorption under impact, and evaluating impact properties of foams is vital. Therefore, a novel test method based on a shock tube was developed to investigate the impact properties of closed-cell polyethylene (PE) foams at strain rates over 6000 s−1, and the test theory is presented. Based on the test method, the failure progress and final failure modes of PE foams are discussed. Moreover, energy absorption capabilities of PE foams were assessed under both quasi-static and high strain rate loading conditions. The results showed that the foam exhibited a nonuniform deformation along the specimen length under high strain rates. The energy absorption rate of PE foam increased with the increasing of strain rates. The specimen energy absorption varied linearly in the early stage and then increased rapidly, corresponding to a uniform compression process. However, in the shock wave deformation process, the energy absorption capacity of the foam maintained a good stability and exhibited the best energy absorption state when the speed was higher than 26 m/s. This stable energy absorption state disappeared until the speed was lower than 1.3 m/s. The loading speed exhibited an obvious influence on energy density.

Targeted Alternation in Properties of Solid Amorphous-Nanocrystalline Material in Exposing to Nanosecond Laser Radiation

2021 ◽  
Vol 410 ◽  
pp. 469-474
Author(s):  
Ivan S. Safronov ◽  
Alexander I. Ushakov
Keyword(s):  
Laser Radiation ◽  
Physical Properties ◽  
Materials Science ◽  
Chemical Properties ◽  
High Energy ◽  
Strength Properties ◽  
Nanosecond Laser ◽  
Processing Modes ◽  
Traditional Processing ◽  
Physical And Chemical

One of the most important purposes of materials science is the ability to govern the physical properties of materials characterized by different structures. The strength properties of nanostructured metal alloys do not always meet the exploitation requirements. The set of properties of such materials is stable within narrow limits: temperature, mechanical, and corrosion conditions. Traditional processing modes are ineffective for such materials. Attempts to use them often lead to the loss of unique physical and chemical properties. The most effective methods of processing such materials are associated with the use of laser radiation. The laser pulse has a number of features, including a complex effect on the surface layers of the material. Spot and short irradiation with high-energy rays can preserve the unique physical properties of samples as a whole and improve strength indicators without destroying the structure of the material as a whole.

High-Energy Ball Milling and Sintering of Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B Powders Mixtures

2014 ◽  
Vol 802 ◽  
pp. 20-24 ◽  
Author(s):  
Lucas Moreira Ferreira ◽  
Luciano Braga Alkmin ◽  
Érika C.T. Ramos ◽  
Carlos Angelo Nunes ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Equilibrium Structures ◽  
Rotary Speed ◽  
Steel Balls

The milling process of elemental Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B (at-%) powder mixtures were performed in a planetary Fritsch P-5 ball mill using stainless steel vials (225 mL) and hardened steel balls (19 mm diameter). Ball-to-powder weight ratio of 10:1 and a rotary speed of 300 rpm were adopted, varying the milling time. Wet milling (isopropyl alcohol) for 20 more minutes was used to increase the yield powder in to the vial. Following the Ti-Ta-Si-B powders milled for 600 min were heat-treated at 1100°C for 1 h in order to obtain the equilibrium structures. The milled powders and heat-treated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Supersaturated Ti solid solutions were formed during ball milling of Ti-Ta-Si-B powders while that the Ti5Si3 phase was formed after milling for 620 min of the Ta-richer powder mixture only. The particles sizes were initially increased during the initial milling times, and the wet milling provided the yield powder into the vials. A large amount of pores was found in both the sintered samples which presented the formation of the TiSS,(ss-solid solution) Ti6Si2B and TiB.

American tulipwood (Liriodendron tulipifera L.) as an innovative material in CLT technology

2021 ◽  
Vol 115 ◽  
pp. 18-28
Author(s):  
Teresa Kłosińska
Keyword(s):  
Robinia Pseudoacacia ◽  
Abies Alba ◽  
Liriodendron Tulipifera ◽  
Wood Products ◽  
Raw Material ◽  
Adjacent Layer ◽  
White Fir ◽  
Innovative Material ◽  
Production Technologies ◽  
Robinia Pseudoacacia L

American tulipwood (Liriodendron tulipifera L.) as an innovative material in CLT technology. CLT (cross laminated timber, X-Lam) is one type of engineered wood products. The first idea of CLT was presented in the seventies of the last century. It is manufactured with timber boards placed side by side commonly with 3, 5 and 7 layers glued at 90 degrees to adjacent layer. The CLT production technology was developed for softwood. The main species in CLT production is Norway spruce (Picea abies L.) and less often White fir (Abies alba Mill.). Hardwood is also used more and more for production of CLT, most often, the wood of Silver birch (Betula pendula Roth.), Ash (Fraxinus excelsior L.), poplars (Populus spp.), Locust tree (Robinia pseudoacacia L.). This paper describes the suitability of cheap tulipwood (Liriodendron tulipifera L.) as a raw material for the production of CLT. Examples of the use of this type of panels in construction are also presented. The tulipwood has similar physical characteristics to softwood, for which CLT production technologies were previously developed. This makes it possible to use the technology previously for softwood CLT was developed. In addition, the tulipwood is characterized by aesthetic visual quality (wood surface similar to marble). Thanks to this, CLT boards to make exposed surfaces can be used.

Synthetic Fibres for Fibre Concrete Composites

1993 ◽  
Vol 305 ◽  
Author(s):  
Dorel Feldman ◽  
Zhihong Zheng
Keyword(s):  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Dynamic Strength ◽  
Strength Properties ◽  
Fibre Volume ◽  
Fibre Reinforcement ◽  
Polypropylene Fibres ◽  
Fibre Concrete ◽  
Deformation Properties ◽  
General Aspects

AbstractThe use of fibrous reinforcement to improve the strength and deformation properties of concrete is now well established. The concept of fibre reinforcement is to use the deformation of the matrix under stress to transfer load to the fibre. Substantial improvements in static and dynamic strength properties could then be achieved if the fibres are strong and stiff, and loaded to fracture, provided there is, of course, a minimum fibre-volume fraction.Besides fibres like asbestos, glass and steel, different kind of synthetic fibres such as polyethylene, polypropylene, polyamide and others are recently used for cementitious composites.Together with general aspects of synthetic fibre concrete composites, original results concerning the study done on a hybrid composite based on steel and polypropylene fibres will be presented and discussed.

Estimation of Creep-Fatigue Damage Through Indentation Test Method

2011 ◽  
Author(s):  
Raghu V. Prakash
Keyword(s):  
Tensile Properties ◽  
Fatigue Damage ◽  
Indentation Test ◽  
Creep Damage ◽  
Test Method ◽  
Specimen Preparation ◽  
Creep Fatigue ◽  
Critical Components ◽  
The Cost

Creep, creep-fatigue damage is often estimated through in-situ metallography, tensile testing of specimens. However, these methods require specimen preparation which includes specimen extraction from critical components. Automated ball indentation testing has been used as an effective tool to determine the mechanical properties of metallic materials. In this work, the tensile properties of materials subjected to controlled levels of damage in creep, creep-fatigue is studied. It is found that the tensile properties such as yield strength and UTS deteriorates with creep damage, whereas the same specimens show an improved UTS values (at the cost of ductility) when subjected to creep-fatigue interactions.

Full-Scale Reeling Tests of HFI Welded Line Pipe for Offshore Reel-Laying Installation

2014 ◽  
Author(s):  
Karl Christoph Meiwes ◽  
Susanne Höhler ◽  
Marion Erdelen-Peppler ◽  
Holger Brauer
Keyword(s):  
Mechanical Testing ◽  
Mechanical Test ◽  
Strength Properties ◽  
Full Scale ◽  
Bending Test ◽  
Small Scale ◽  
Pipe Material ◽  
Deformation Capacity ◽  
Line Pipe ◽  
Tension And Compression

During reel-laying repeated plastic strains are introduced into a pipeline which may affect strength properties and deformation capacity of the line pipe material. Conventionally the effect on the material is simulated by small-scale reeling simulation tests. For these, coupons are extracted from pipes that are loaded in tension and compression and thermally aged, if required. Afterwards, specimens for mechanical testing are machined from these coupons and tested according to the corresponding standards. Today customers often demand additional full-scale reeling simulation tests to assure that the structural pipe behavior meets the strain demands as well. Realistic deformations have to be introduced into a full-size pipe, followed by aging, sampling and mechanical testing comparable to small-scale reeling. In this report the fitness for use of a four-point-bending test rig for full-scale reeling simulation tests is demonstrated. Two high-frequency-induction (HFI) welded pipes of grade X65M (OD = 323.9 mm, WT = 15.9 mm) from Salzgitter Mannesmann Line Pipe GmbH (MLP) are bent with alternate loading. To investigate the influences of thermal aging from polymer-coating process one test pipe had been heat treated beforehand, in the same manner as if being PE-coated. After the tests mechanical test samples were machined out of the plastically strained pipes. A comparison of results from mechanical testing of material exposed to small- and full-scale reeling simulation is given. The results allow an evaluation of the pipe behavior as regards reeling ability and plastic deformation capacity.

In-plane Shear Measurements of Textile Composites with Large Unit Cells using the Plate Twist Test

2002 ◽  
Vol 10 (7) ◽  
pp. 511-520
Author(s):  
G. Weissenbach ◽  
D. Brown ◽  
L. Limmer
Keyword(s):  
Textile Composites ◽  
Test Method ◽  
Shear Behaviour ◽  
Specimen Preparation ◽  
Plane Shear ◽  
Test Fixture ◽  
Large Unit ◽  
Unit Cells ◽  
Set Up ◽  
Woven Textile

The application of the plate twist test method to 3D-woven textile composites was investigated using both numerical analyses of the test set-up as well as experimental results. Comparisons with the widely used V-notched beam shear and 10°-off-axis tension tests are introduced in an attempt to identify the true in-plane shear response. The results of this study demonstrate that with careful specimen preparation and an adequate test fixture precise in-plane shear modulus data can be obtained. Moreover, for 3D-woven textile composites with their large unit cells the plate twist test appears to be superior in revealing the “true” in-plane shear behaviour.

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