Bulging Distortion of Austenitic Stainless Steel Sheet on the Partially Penetrated Side of Non-Penetration Lap Laser Welding Joint

Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost importance.However,the application of non-penetration welded austenitic stainless steel parts is limited owing to the micro bulging distortion that occurs on the back surface of the partial penetration side.In this paper,non-penetration lap laser welding experiments,were conducted on galvanized and SUS304 austenitic stainless steel plates using a fiber laser,to investigate the mechanism of bulging distortion.A comparative experiment of DC01 galvanized steel-Q235 carbon steel lap laser welding was carried out,and the deflection and distortion profile of partially penetrated side of the sheets were measured using a noncontact laser interferometer.In addition,the cold-rolled SUS304 was subjected to heat holding at different temperatures and water quenching after bending to characterize its microstructure under tensile and compressive stress.The results show that,during the heating stage of the thermal cycle of laser lap welding,the partial penetration side of the SUS304 steel sheet generates compressive stress,which extrudes the material in the heat-affected zone to the outside of the back of the SUS304 steel sheet,thereby forming a bulge.The findings of these experiments can be of great value for controlling the distortion of the partial penetrated side of austenitic stainless steel sheet during laser non-penetration lap welding.

MODELING COMPLIANT NON-PENETRATION CONSTRAINT FOR VP MOTION SIMULATION

A unilateral non-penetration constraint dynamical simulation model withfriction is constructed based on compliant model for mechanical system VP (virtual prototyping)simulation. This model combines computer graphics with multi-body system dynamics. It avoidshandling multiplicity of solution, such as cases of no solution, multi-solution brought about byfriction during traditional construction of non-penetration constraint based on rigid model. At thesame time, the realism of VE (virtual environment) is improved in process of simulation.Furthermore, the valid condition of rolling and sliding unilateral contact is constituted based onsingular perturbation and linear complementary theory. Finally, the compliant method is verified byan interaction between a multi-legged robot and VE.

Fatigue Resistance and Failure Behavior of Penetration and Non-Penetration Laser Welded Lap Joints

Penetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars,while their fatigue performances and the difference between them are not completely understood.In this study,the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated.The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance,and their hardness was lower than that of the plates.The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes,whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes.The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture,respectively,and the primary cracks were initiated at welding fusion lines on the lap surface.There were long plastic ribs on the penetration plate fracture,but not on the non-penetration plate fracture.The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa,respectively,which can be used as reference stress for the fatigue design of the laser welded structures.The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.

Experimental study of the damage characteristics of rocks containing non-penetrating cracks under cyclic loading

The damage evolution process of non-penetrating cracks often causes some unexpected engineering disasters.Gypsum specimens containing non-penetrating crack(s)are used to study the damage evolution and characteristics under cyclic loading.The results show that under cyclic loading,the relationship between the number of non-penetrating crack(s)and the characteristic parameters(cyclic number,peak stress,peak strain,failure stress,and failure strain)of the pre-cracked specimens can be represented by a decreasing linear function.The damage evolution equation is fitted by calibrating the accumulative plastic strain for each cycle,and the damage constitutive equation is proposed by the concept of effective stress.Additionally,non-penetrating cracks are more likely to cause uneven stress distribution,damage accumulation,and local failure of specimen.The local failure can change the stress distribution and relieve the inhibition of non-penetrating crack extension and eventually cause a dramatic destruction of the specimen.Therefore,the evolution process caused by non-penetrating cracks can be regarded as one of the important reasons for inducing rockburst.These results are expected to improve the understanding of the process of spalling formation and rockburst and can be used to analyze the stability of rocks or rock structures.

Meta Analysis of Non-penetrating Trabecular Surgery versus Trabeculectomy for the Treatment of Open Angle Glaucoma

This study compared the efficacy of non-penetrating trabecular surgery and trabeculectomy for the treatment of open angle glaucoma. We searched the Cochrane Library, PUBMED （1966 to 2009）, Embase （1980 to 2009） and CMB-disk （1979 to 2009） for the randomized clinical trials （RCT） concerning the two treatment strategies. The reports, including the papers listed in bibliographies, were evaluated against a set of quality criteria and the RCTs that satisfied the criteria were selected and subjected to Meta analysis by employing the Cochrane Collaboration＇s RevMan 4.5 software package. A total of nine RCTs were included in the study. The analyses of the reports showed that, 12 months after surgery, there was significant difference in the reduction of interocular pressure （IOP） between non-penetrating trabecular surgery and trabeculectomy （Z=6.05 P0.00001）. There also existed statistically significant difference in the reduction of IOP at the censored time between the two procedures （Z=4.92, P0.00001）. Difference in the success rate was also found between the two surgeries （Z=3.82, P=0.0001）. It is concluded that, compared with the non-penetrating trabeculectomy, the traditional trabeculectomy could reduce IOP more and had higher success rate while the non-penetrating trabecular surgery is associated with lower postoperative complications.

IOP-lowering effects for the application of human umbilical vein in non-penetrating deep sclerostomy in rabbits

AIM: To estimate the effects of human umbilical vein (HUV) implanted under the sclera of glaucoma model on intraocular pressure (IOP) lowering and to investigate its related mechanisms METHODS: A total of 20 human umbilical veins (HUV) were collected from healthy fetus umbilical core. After the establishment of glaucoma model in rabbits, human freeze-dried umbilical vein was implanted under the sclera during NPDS, while for control group, sclerostomy was performed without implant. The formation of the filtration bleb and TOP were detected every 24 hours before surgery and on day 3, 7, 10 and 14 after surgery. Handheld pen-type Tono-pen II tonometer was used to measure TOP after topical anesthesia treatment. Each measurement has three duplicates. The incision recovery, filtration, conjunctiva congestion and anterior chamber inflammation were observed everyday after surgery. RESULTS: IOP was decreased dramatically with less inflammation than traditional sclerostomies with the application of HUV. The significant differences of IOP between the NPDS with and without HUV implant groups were shown up from 10 days after surgery. The average TOP in NPDS without HUV implant was 14.25mmHg, while for NPDS with HUV implant group, it was 12.30mmHg. This structure of filtration bleb, which allowed the aqueous humor to leave the eye, was formed for any type of surgery. However, 1-2 weeks later, filtration bleb was still Existed in the group of sclerostomy with HUV implant and more stable than that of the surgery without HUV implant. Histological observations were performed on day 3, 7 and 14 after surgery. For the eyes under sclerostomy with HUV implant, HUV lumina was shown up on 3 days after surgery with few fibroblast cells near the sclera. On 7 days after surgery, HUV lumina was stably maintained but with obvious fibroblast cells and inflammatory cell. On 14 days after surgery, HUV lumina was still clearly observed but with scarring formation, which suggests that the IOP lowering effects might result from an effective drainage structure formation. CONCLUSION: HUV might be an alternative material to make the drainage pathway for non-penetrating deep sclerostomy.

Efficacy and safety of non-penetrating glaucoma surgery with phacoemulsification versus non-penetrating glaucoma surgery:a Meta-analysis

AIM:To compare the clinical efficacy and safety of non-penetrating glaucoma surgery(NPGS)plus phacoemulsification(Phaco-NPGS)and NPGS-alone.METHODS:We systematically searched various databases and reviewed studies that had evaluated the effects of Phaco-NPGS or NPGS-alone for patients with glaucoma.Primary outcomes included postoperative intraocular pressure(IOP)and the number of postoperative antiglaucoma medications.Secondary outcomes were the prevalence of complications,incidence of needling or goniopuncture,and surgical success rate.RESULTS:In total,380 and 424 eyes in NPGS-alone and Phaco-NPGS groups respectively were included.Both postoperative IOP and number of medications were significantly lowered in the Phaco-NPGS group than that in the NPDS-alone group[weighted mean difference(WMD)=-1.12,95%confidence interval(CI):-2.11 to-0.12,P=0.03;WMD=-0.31,95%CI:-0.53 to-0.09,P=0.006].Moreover,Phaco-NPGS had a significantly lower prevalence of complications and postoperative procedures compared to NPGS-alone,while no significant difference existed for surgical success.CONCLUSION:Phaco-NPGS superior to NPGS-alone in the reduction of IOP and medications.Phaco-NPGS can be recommended for glaucoma patients with coexisting cataracts owing to its superior efficacy,fewer complications,and postoperative procedures.

Modified viscocanalostomy in the Chinese population with open angle glaucoma: a 10-year follow-up results

AIM: To study the long-term efficacy and safety of modified viscocanalostomy in Chinese people with open angle glaucoma(OAG).METHODS: This retrospective study included a total of 100 eyes from 100 Chinese patients with medically uncontrolled OAG. All the patients underwent modified viscocanalostomy with injection of viscoelastic material in the surgically created ostia of Schlemm's canal(SC). The modifications included peeling of the inner wall of SC and the juxtacanalicular meshwork, use of mitomycin C, and loosely suturing the superficial scleral flap. Intraocular pressure(IOP), visual acuity, number of medications, laser goniopuncture data and complications were recorded. The definition of complete(qualified) success was an IOP equal to or lower than 21, 18, 16 mm Hg without(with or without) anti-glaucoma medications. RESULTS: The mean IOP was 33.5±9.9 mm Hg before surgery, 15.2±3.6 mm Hg(mean IOP reduction of 51%) at 5 y after surgery, and 15.6±2.8 mm Hg(mean IOP reduction of 49.9%) at 10 y after surgery(P<0.001). The number of anti-glaucoma medications dropped from 2.39±0.5 preoperatively to 0.47±0.8 at 5 y and 0.67±0.8 at 10 y postoperatively(P<0.001). The follow-up period was 104.5±37.0 mo. The qualified success rate for an IOP of 21, 18 or 16 mm Hg or less was 84% [95% confidence interval(CI): 0.80-0.88], 73%(95%CI: 0.68-0.78), and 59%(95%CI: 0.52-0.66) after 5 y, and 80%(95%CI: 0.76-0.84), 69%(95%CI: 0.64-0.74), 51%(95%CI: 0.44-0.58) after 10 y, respectively. There was a relationship between age, preoperative IOP and success rate(P<0.01, P<0.05). A total of 31 eyes(31.3%)in 31 patients underwent laser goniopuncture, decreasing the IOP from 22.9±4.3 mm Hg to 16.3±2.5 mm Hg(P<0.01). Neither blebitis nor endophthalmitis occurred.CONCLUSION: Modified viscocanalostomy could be performed to lower IOP, decrease multiple anti-glaucoma drops use as well. It's a safe procedure with less complications over 10 y in Chinese individuals with OAG.

Long-term results of viscocanalostomy and phacoviscocanalostomy: a twelve-year follow-up study

AIMTo evaluate the long-term efficacy and safety results of viscocanalostomy and phacoviscocanalostomy.METHODSThe charts of 49 glaucoma patients who underwent viscocanalostomy or phacoviscocanalostomy surgery between February 1999 and August 2004 were reviewed retrospectively. Thirty-one eyes of 21 glaucoma patients who underwent filtering procedure with a postoperative follow-up of at least 5y were included in the study. Results of complete ophthalmologic examinations were recorded and statistically analyzed. Long-term surgical outcome was defined as an overall success when intraocular pressure (IOP) was found as &#x02264;20 mm Hg with or without antiglaucomatous medication at the last follow-up visit, while it was defined as a complete success when IOP was measured &#x02264;20 mm Hg without antiglaucomatous medication.RESULTSMean age was 68.1&#x000b1;9.6y (range: 32-81y). Mean follow-up time was 101.5&#x000b1;27.3mo (range: 60-144mo). Viscocanalostomy was performed in 8 eyes (25.8%) and phacoviscocanalostomy was performed in 23 eyes (74.2%). The mean preoperative IOP was 23.1&#x000b1;7.6 mm Hg with 2.1&#x000b1;1.0 medications, while mean IOP was 16.8&#x000b1;3.8 mm Hg with 0.9&#x000b1;1.1 medication at the last follow-up visit. Both the IOP decrease and the reduction in the antiglaucomatous medication were statistically significant (P&#x0003c;0.001 and P&#x0003c;0.001). No case required further glaucoma surgery. Overall success and complete success were found as 87.1% and 51.6%, respectively. Complete success rate was statistically higher in phacoviscocanalostomy group compared with the viscocanalostomy group (P=0.031), however there was no significant difference in overall success rate between two groups (P=0.072).CONCLUSIONBoth viscocanalostomy and phacoviscocanalostomy provide good IOP reduction in the long-term period.

Efficacy of non-penetrating trabecular surgery for open angle glaucoma: a meta-analysis

Background Non-penetrating trabecular surgery is a new filtrating surgery without opening in ternal trabecular structures. This study was to estimate the overall efficacy of non-penetrating trabecular surgery for open angle glaucoma.Methods The published articles selected for this study were obtained by a computerised Medline and China Biological Medicine Disk search of the literature and a manual search of the bibliographies of relevant articles. Articles meeting the inclusion criteria were reviewed systematically, and the reported data were aggregated using the statistical techniques of meta-analysis.Results A total of 37 articles were included in the meta-analysis. The pooled complete success rates of non-penetrating trabecular surgery with different techniques were: deep sclerectomy single, 69.7% (95% CI: 58.5%-81.0%); deep sclerectomy with collagen implant, 59.4% (95% CI: 47.0%-71.8%); deep sclerectomy with reticulated hyaluronic acid implant, 71.1% (95% CI: 56.8%-85.3%); and viscocanalostomy, 72.0% (95% CI: 57.6%-86.4%). The overall weighted complete success rate of non-penetrating trabecular surgery was 67.8% (95% CI: 61.4%-74.3%).Conclusions Non-penetrating trabecular surgery is the best available therapy method for medically uncontrolled open angle glaucoma with a complete success rate of over 60%. But the different techniques cannot belie the complete success rate of non-penetrating trabecular surgery.

A fast and automatic full-potential finite volume solver on Cartesian grids for unconventional configurations

To meet the requirements of fast and automatic computation of subsonic and transonic aerodynamics in aircraft conceptual design,a novel finite volume solver for full potential flows on adaptive Cartesian grids is developed in this paper.Cartesian grids with geometric adaptation are firstly generated automatically with boundary cells processed by cell-cutting and cell-merging algorithms.The nonlinear full potential equation is discretized by a finite volume scheme on these Cartesian grids and iteratively solved in an implicit fashion with a generalized minimum residual（GMRES） algorithm.During computation,solution-based mesh adaptation is also applied so as to capture flow features more accurately.An improved ghost-cell method is proposed to implement the non-penetration wall boundary condition where the velocity-potential of a ghost cell is modified by an analytic method instead.According to the characteristics of the Cartesian grids,the Kutta condition is applied by specially computing the gradients on Kutta-faces without directly assigning the potential jump to cells adjacent wake faces,which can significantly improve the solution converging speed.The feasibility and accuracy of the proposed method are validated by several typical cases of sub/transonic flows around an ONERA M6 wing,a DLR-F4 wing-body,and an unconventional figuration of a blended wing body（BWB）.The validation cases demonstrate a fast convergence with fully automatic grid treatment and computation,and the results suggest its capacity in application for aircraft conceptual design.

Timoshenko inclusions in elastic bodies crossing an external boundary at zero angle

The paper concerns an analysis of equilibrium problems for 2D elastic bodies with a thin Timoshenko inclusion crossing an external boundary at zero angle. The inclusion is assumed to be delaminated, thus forming a crack between the inclusion and the body. We consider elastic inclusions as well as rigid inclusions. To prevent a mutual penetration between the crack faces, inequality type boundary conditions are imposed at the crack faces. Theorems of existence and uniqueness are established. Passages to limits are investigated as a rigidity parameter of the elastic inclusion going to infinity.