Compression Properties and Energy Absorption of A Novel Double Curved Beam Negative Stiffness Honeycomb Structures

This paper presents the design of a novel honeycomb structure with a double curved beam.The purpose of this design is to achieve vibration isolation for the main engine of an offshore platform and reduce impact loads.An analytical formula for the force-displacement relationship of the honeycomb single-cell structure is presented based on the modal superposition method.This formula provides a theoretical basis for predicting the compression performance of honeycomb structures.The effects of structural geometric parameters,series and parallel connection methods on the mechanical and energy absorption properties are investigated through mathematical modeling and experimental methods.Furthermore,the study focuses on the vibration isolation and impact resistance performance of honeycomb panels.The results show that the designed honeycomb structure has good mechanical and energy absorption performance,and its energy absorption effect is related to the geometric parameters and series and parallel connection methods of the structure.The isolation efficiency of the honeycomb with 4 rows and 3 columns reaches 38%.The initial isolation frequency of the isolator is 11.7 Hz.

Effect of Weft Binding Structure on Compression Properties of Three-Dimensional Woven Spacer Fabrics and Composites

With the wide use of three-dimensional woven spacer composites(3DWSCs),the market expects greater mechanical properties from this material.By changing the weft fastening method of the traditional I-shape pile yarns,we designed three-dimensional woven spacer fabrics(3DWSFs)and 3DWSCs with the weft V-shape to improve the compression performance of traditional 3DWSFs.The effects of weft binding structures,V-pile densities,and V-shaped angle were investigated in this paper.It is found that the compression resistance of 3DWSFs with the weft V-shape is improved compared to that with the weft I-shape,the fabric height recovery rate is as high as 95.7%,and the average elastic recovery rate is 59.39%.When the interlayer pile yarn density is the same,the weft V-shaped and weft I-shaped 3DWSCs have similar flatwise pressure and edgewise pressure performance.The compression properties of the composite improve as the density of the V-pile yarns increases.The flatwise compression load decreases as the V-shaped angle decreases.When the V-shaped angle is 28°and 42°,the latitudinal V-shaped 3DWSCs perform exceptionally well in terms of anti-compression cushioning.The V-shaped weft binding method offers a novel approach to structural design of 3DWSCs.

Effects of Yttrium and Cerium on Compression Properties of Ni_3Al-Base Alloys

The effects of yttrium and cerium on the compression properties of Ni_3Al-base alloys have been investigated.The results reveal that the addition of about 0.1 wt% Y to Ni_3Al-B alloy is effective for improving the ductility at 1100℃.A ductility increase of about 100% is observed for this Y doped alloy.The yttrium re- fines grains of the alloy.An YNi_5 phase is found to be precipitated on the grain boundaries in the alloy con- taining 0.3 wt% Yor more.Adding about 0.1 wt% Ce to Ni_3Al-B-Cr-Zr alloy obviously improves the ductility of the alloy at 1100℃.A ductility increase of about 50% is obtained for this alloy.The added cerium also pre- vents the formation of γ+γ' eutectic and refines it.The bulk phase of CeNi_4 appeares at the front of the eutectic in the alloys containing 0.1 wt% Ce or more.

Axial Compression Properties of 3D Woven Special⁃Shaped Square Tubular Composites with Basalt Filament Yarns

In order to avoid the delamination of traditional laminated tubular composites,on an ordinary loom,the 3D woven special⁃shaped square tubular fabrics were woven with environment⁃friendly basalt filament yarns,and then the 3D woven special⁃shaped square tubular composites were prepared with epoxy resin by a vacuum⁃assisted resin transfer molding(VARTM)process.Through experiments and software fitting,the axial compression properties of composites were analyzed.The polynomial fitting formulas of load⁃displacement curve and energy⁃displacement curve were obtained by using least square methods.The results showed that the 3D woven special⁃shaped square tubular composites had good axial compression performance,and with the increase of the composite thickness,compressive strength and energy absorption increased significantly.The failure mode was analyzed in the paper,thus revealing the failure stress propagation,local stress concentration,and failure morphology.It provides an effective reference for the design and application of the 3D woven special⁃shaped square tubular composite.

Mechanical properties and deformation behavior of Zr-based bulk metallic glass composites reinforced with tungsten fibers or tungsten powders

The tungsten fibers or powders reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10),(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2),and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)bulk metallic glass composites(BMGCs)were fabricated using the infiltration casting method.In this study,the wettability between the amorphous alloy melts and tungsten substrates was investigated using the sessile drop method,revealing excellent wettability at 1,010℃.Consequently,an infiltration temperature of 1,010°C was chosen for composite material fabrication.Structural characterization and mechanical property test of both composites were conducted through scanning electron microscopy(SEM),and X-ray diffraction(XRD),and universal mechanical testing.Both tungsten fiber or tungsten powder reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10)and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)composites exhibit the formation of W-Zr phase.In contrast,the tungsten fiber or tungsten powder reinforced(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2)composites does not show the formation of W-Zr phase.X-ray diffraction patterns confirm the presence of W reinforcement phases in both composites.The successful fabrication of both composites is evidenced by their remarkable mechanical properties under room temperature compression.The yield strength of all the three tungsten fiber-reinforced composite sample exceeds 2,400 MPa,with the plastic strain exceeding 3.9%,while the yield strength of all the three tungsten powder-reinforced composite sample surpasses 2,700 MPa,with the plastic strain exceeding 30%.Fracture analysis reveals longitudinal splitting in the tungsten fiber-reinforced composites,contrasting with brittle fracture in the tungsten powder-reinforced composites.The denser the shear bands on the amorphous matrix of the two types of composite materials,the better their mechanical properties.

Compressive Mechanical and Heat Conduction Properties of AlSi10Mg Gradient Metamaterials Fabricated via Laser Powder Bed Fusion

Metamaterials are defined as artificially designed micro-architectures with unusual physical properties,including optical,electromagnetic,mechanical,and thermal characteristics.This study investigates the compressive mechanical and heat transfer properties of AlSi10Mg gradient metamaterials fabricated by Laser Powder Bed Fusion(LPBF).The morphology of the AlSi10Mg metamaterials was examined using an ultrahigh-resolution microscope.Quasi-static uniaxial compression tests were conducted at room temperature,with deformation behavior captured through camera recordings.The findings indicate that the proposed gradient metamaterial exhibits superior compressive strength properties and energy absorption capacity.The Gradient-SplitP structure demonstrated better compressive performance compared to other strut-based structures,including Gradient-Gyroid and Gradient-Lidinoid structures.With an apparent density of 0.796,the Gradient-SplitP structure exhibited an outstanding energy absorption capacity,reaching an impressive 23.57 MJ/m^(3).In addition,heat conductivity tests were performed to assess the thermal resistance of these structures with different cell configurations.The gradient metamaterials exhibited higher thermal resistance and lower thermal conductivity.Consequently,the designed gradient metamaterials can be considered valuable in various applications,such as thermal management,load-bearing,and energy absorption components.

Effect of minor B addition on microstructure and properties of AlCoCrFeNi multi-compenent alloy

The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys（x = 0,0.01,…,0.09 and 0.1,mole fraction） were investigated.The AlCoCrFeNi high entropy alloy exhibits equiaxed grain structures with obvious composition segregation.However,with the addition of B element,the alloys exhibit dendrite structures.Inside the dendrites,spinodal decomposition structure can be clearly observed.With the addition of B element,the crystal structures change from（B2 ＋ BCC） to（B2 ＋ BCC ＋ FCC） structures,and the hardness firstly increases from HV 486.7 to HV 502.4,then declines to HV 460.7（x ≥ 0.02）.The compressive fracture strength firstly shows a trend of increasing,and then declining（x ≥ 0.08）.The coercive forces and the specific saturation magnetizations of the alloys decrease as B addition contents increase,the decreasing coercive forces show a better soft magnetic behavior.

Microstructures,corrosion and mechanical properties of as-cast Mg-Zn-Y-(Gd)alloys

Long period stacking ordered（LPSO） structure phases were prepared by conventional solidification method in Mg（94）Zn3YxGd（3-x）（x=3,2,1.5,1,mole fraction） alloys,the microstructures,corrosion and compressive mechanical properties of which were investigated,separately.The results reveal that the microstructures of the as-cast Mg（94）Zn3YxGd（3-x） alloys,with n（Zn）/n（Y＋Gd）=1：1,consist of α（Mg） phase,Mg3Zn3RE2（W） phase,Mg（12）ZnRE（14H-LPSO） phase and a few bright cube-shaped Mg-Y-Gd phases.The formation and the distribution of LPSO-phase in the alloys can be influenced by the content of Gd.The volume fraction of 14H-LPSO phase increases first and then decreases with the increase of the Gd content.For the electrochemical impedance spectroscopy（EIS） measurement,a R（Q（R（QR））） model was used to fit the test results in 3.5%（mass fraction） NaCl solution at room temperature.The corrosion current densities of all samples are about 10-（-5） A/cm-2.When x（Gd）≤1%,Mg-Zn-Y-（Gd）alloy shows good corrosion resistance,which is better than that of the commercial AZ91 D magnesium alloy.The corrosion rate increases when the Gd content is higher than 1.5%.At room temperature,the compressive properties of Mg-Zn-Y-（Gd） alloys increase remarkably with the increase of the volume fraction of LPSO phase.In addition,the pinning effect of W-phase and dispersive cube-shaped Mg-Y-Gd phase is beneficial to improving the mechanical properties of as-cast Mg（94）Zn3YxGd（3-x） alloy in deformation process.

Influence of hydrogen content on room temperature compressive properties of Ti-6Al-4V alloy at high strain rate

Electromagnetic forming tests were done at room temperature to reveal the influence of hydrogen content on the compressive properties of Ti-6Al-4V alloy at high strain rate. Microstructure was observed to reveal the mechanism of hydrogen-enhanced compressive properties. The experimental results indicate that hydrogen has favorable effects on the compressive properties of Ti-6Al-4V alloy at high strain rate. Compression of Ti-6Al-4V alloy first increases up to a maximum and then decreases with the increase of hydrogen content at the same discharge energy under EMF tests. The compression increases by 47.0% when 0.2% (mass fraction) hydrogen is introduced into Ti-6Al-4V alloy. The optimal hydrogen content for cold formation of Ti–6Al–4V alloy under EMF was determined. The reasons for the hydrogen-induced compressive properties were discussed.

Mechanical Properties and Energy Absorption of Integrated AlSi10Mg Shell Structures with BCC Lattice Infill

Shell-infill structures comprise an exterior solid shell and an interior lattice infill,whose closed features yield superior comprehensive mechanical performance and light weight.Additive manufacturing(AM)can ensure the fabrica-tion of complex structures.Although the mechanical behaviors of lattice structures have been extensively studied,the corresponding mechanical performances of integrated-manufactured shell structures with lattice infills should be systematically investigated due to the coupling effect of the exterior shell and lattice infill.This study investigated the mechanical properties and energy absorption of AlSi10Mg shell structures with a body-centered cubic lattice infill fabricated by AM.Quasi-static compressive experiments and corresponding finite element analysis were conducted to investigate the mechanical behavior.In addition,two different finite element modeling methods were compared to determine the appropriate modeling strategy in terms of deformation behavior.A study of different parameters,including lattice diameters and shell thicknesses,was conducted to identify their effect on mechanical performance.The results demonstrate the mechanical advantages of shell-infill structures,in which the exterior shell strengthens the lattice infill by up to 2.3 times in terms of the effective Young’s modulus.Increasing the infill strut diameter can improve the specific energy absorption by up to 1.6 times.

Fabrication,structure and compression performance of Inconel 617 superalloy honeycomb

Inconel 617 metal honeycombs with designed porosity,cell size and cell morphology were fabricated using fused deposition modelling rapid prototype manufacturing.The microstructure and compression properties of Inconel 617 metal honeycomb were studied.The results indicate that Inconel 617 metal honeycomb structure can be fabricated using fused deposition modelling technique,the processes are simple and the size of honeycomb is controllable.The sintered Inconel 617 honeycombs consist of matrix,γ phase,and grain boundary precipitates,Cr7C3 and M23C6 type carbides.The honeycomb microstructure sintered using fine powder particles are denser than that of coarse powder particles.Yield strength and Young’s modulus increase with the relative density of honeycomb increasing.But the influence of the relative density on Young’s modulus is greater than that of yield strength.

Compressive properties and energy absorption characteristics of open-cell nickel foams

Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region.

Effects of foaming parameters on microstructure and compressive properties of aluminum foams produced by powder metallurgy method

Semi open-cell aluminum foams having channels between individual cells were produced using low cost CaCO3foamingagent and applying the powder compact melting process.To this end,the aluminum and CaCO3powder mixtures were coldcompacted into dense cylindrical precursors for foaming at specific temperatures under air atmosphere.The effects of severalparameters including precursor compaction pressure,foaming agent content as well as temperature and time of the foaming processon the cell microstructure,linear expansion,relative density and compressive properties were investigated.A uniform distribution ofcells with sizes less than100μm,which form semi open-cell structures with relative densities in the range of55.4%-84.4%,wasobtained.The elevation of compaction pressure between127-318MPa and blowing agent up to15%(mass fraction)led to anincrease in the linear expansion,compressive strength and densification strain.By varying the foaming temperature from800to1000°C,all of the investigated parameters increased except compressive strength and relative density.The results indicated theoptimal foaming temperature and time as900°C and10-25min,respectively.

Effects of porosity and pore size on the compressive properties of closed-cell Mg alloy foam

In our current work,AZ31 magnesium alloy foams with closed-cell were successfully fabricated by melt foaming method using Ca and CaCO3 as thickening and blowing agent,respectively.The influences of porosity and pore size on the quasi-static compressive properties of the foams were systematically investigated.The results showed that the yield strength,energy absorption capacity and ideality energy absorption efficiency were decreased with the increase in porosity.However,specimens with porosities of 60%,65%and 70%possessed similar total energy absorption capacity and ideality energy absorption efficiency.Meanwhile,experimental results showed that mean plateau strength of the foams was increased first and then decreased with increase in mean pore size.In addition,energy absorption capacities were almost the same in the initial stage,while the differences were obvious in the middle stage.From the engineering point of view,the specimens with mean pore size of 1.5 mm possess good combination of mean plateau strength and energy absorption characteristics under the present conditions.

Microstructure and properties of novel quinary multi-principal element alloys with refractory elements

Five equiatomic alloys(Ti Zr Hf VNb, Ti Zr Hf VTa, Ti Zr Nb Mo V, Ti Zr Hf Mo V and Zr Nb Mo Hf V) composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are composed with Laves phase(Hf Mo2) and disordered solid solution phases with body-centered cubic structure. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the Ti Zr Hf VNb and Ti Zr Hf Mo V alloys. Solution strengthening is the primary strengthening mechanism of the Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys, and brittle Laves phase is the main cause for the low ductility of the Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys.

Effect of Zr on microstructure and mechanical properties of binary TiAl alloys

Ti43Al and Ti47Al alloys with different contents of zirconium were prepared by non-consumable vacuum arc melting furnace.The microstructure and mechanical properties were investigated.The results showed that Zr had no obvious effect on microstructure morphology of Ti43Al,while that of Ti47Al was modified from dendrites into equiaxed grains.The addition of Zr could refine the grains.Zr promoted the formation ofγphase significantly and the solubility values of Zr inγphase were 12.0%and 5.0%(molar fraction)in Ti43Al and Ti47Al,respectively.Zr-richγphase mainly formed throughβ→γin Ti43Al-xZr(molar fraction,%)andβ→α→γin Ti47Al-xZr(molar fraction,%).Fine-grain strengthening and solution strengthening were beneficial to improving the compressive strength while severe micro-segregation was detrimental to compressive properties.Large solubility of Zr was bad for ductility of alloys as well.The maximum compressive strengths of Ti43Al-xZr and Ti47Al-xZr were 1684.82 MPa(x=5.0%)and 2158.03 MPa(x=0.5%),respectively.The compressive strain fluctuated slightly in Ti43Al-xZr and reached the maximum value of 35.24%(x=0.5%)in Ti47Al-xZr.Both alloys showed brittle fracture.

Effect of ball milling time on the microstructure and compressive properties of the Fe–Mn–Al porous steel

In the present work,Fe–Mn–Al–C powder mixtures were manufactured by elemental powders with different ball milling time,and the porous high-Mn and high-Al steel was fabricated by powder sintering.The results indicated that the powder size significantly decreased,and the morphology of the Fe powder tended to be increasingly flat as the milling time increased.However,the prolonged milling duration had limited impact on the phase transition of the powder mixture.The main phases of all the samples sintered at 640℃ were α-Fe,α-Mn and Al,and a small amount of Fe2Al5 and Al8Mn5.When the sintering temperature increased to 1200℃,the phase composition was mainly comprised of γ-Fe and α-Fe.The weight loss fraction of the sintered sample decreased with milling time,i.e.,8.3wt% after 20 h milling compared to15.3wt% for 10 h.The Mn depletion region(MDR) for the 10,15,and 20 h milled samples was about 780,600,and 370 μm,respectively.The total porosity of samples sintered at 640℃ decreased from ~46.6vol% for the 10 h milled powder to ~44.2vol% for 20 h milled powder.After sintering at 1200℃,the total porosity of sintered samples prepared by 10 and 20 h milled powder was ~58.3vol% and ~51.3vol%,respectively.The compressive strength and ductility of the 1200℃ sintered porous steel increased as the milling time increased.

Microstructures and compressive properties of AZ91D/fly-ash cenospheres composites

Novel AZ91D Mg alloy/fly-ash cenospheres(AZ91D/FACs)composites were fabricated by melt stir technique.Fly-ash cenosphere particles with 4%,6%,8%,10%in mass fraction and 100μm in size were used.Hardness and compressive strength of the composites were measured.The effects of mass fraction of cenospheres on the microstructure and compressive properties were characterized.The results show that the cenospheres are uniformly distributed in the matrix and there is no sign of cenosphere cluster or residual pore.The densities of the composites are 1.85-1.92 g/cm 3 .By comparing with matrix,the compressive yield strength of the composites is improved,and the cenospheres is filled with Mg matrix alloy.SEM,XRD and EDX results of the composites show clear evidence of reaction product at cenosphere/matrix interface.On the basis of XRD and EDX,composition, structure and thermodynamic analysis,the main interfacial phase between the cenosphere and AZ91D Mg alloy was identified to be MgAl2O4.

Effect of Mo addition on microstructure, ordering, and room-temperature mechanical properties of Fe-50Al

The effects of Mo addition on microstructures,phase relationships,order–disorder phase-transition temperatures and room-temperature mechanical properties of Fe50Al50-nMon alloys(n=1,3,5,7,and 9,mole fraction,%)were investigated after solidification and heat treatment.Structural characterization of the samples was performed via X-ray diffraction(XRD),scanning electron microscopy(SEM)and differential scanning calorimetry.Room-temperature mechanical properties were investigated by conducting compression and microhardness tests.Mo3Al particles precipitated in all alloys because of the limited solid solubility of Mo in the Fe-Al-based phases.The as-cast Fe50Al50-nMon alloys exhibited brittle behavior with high yield strength and limited fracture strain at room temperature.Compared with the as-cast alloys,all the heat-treated alloys except for the Fe50Al41Mo9 alloy exhibited enhanced mechanical properties at room temperature.The heat-treated Fe50Al43Mo7 alloy exhibited the highest fracture strain and compressive strength of 25.4%and 2.3 GPa,respectively.

Effect of Porosity and Cell Size on the Dynamic Compressive Properties of Aluminum Alloy Foams

The dynamic mechanical properties of open-cell aluminum alloy foams with different relative densities and cell sizes have been investigated by compressive tests. The strain rates varied from 700 s-1 to 2600 s-1. The experimental results showed that the dynamic compressive stress-strain curves exhibited a typical three-stage behavior: elastic, plateau and densification. The dynamic compressive strength of foams is affected not only by the relative density but also by the strain rate and cell size. Aluminum alloy foams with higher relative density or smaller cell size are more sensitive to the strain rate than foams with lower relative density or larger cell size.